IMAGRを使ったImaging & CLEAN


Imagingおよびdeconvolutionの実行 [IMAGR]

実行例1:LCONTにより 取り出したcontinuum dataのimagingおよびCLEANの場合

☆ まずはdirty mapを作る

step-by-stepガイドの復習も兼ねて、まずは visibilityのplot(uv-coverage)を確認してから。

>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 17:10:58     
>getn 187
AIPS 1: Got(1)   disk= 1  user=   1   type=UV   NGC9876CNT.DBCON.1      
>imh   ← headerを見てみる
AIPS 1: Image=AB1CONT   (UV)         Filename=NGC9876CNT  .DBCON .   1  
AIPS 1: Telescope=                                                      
AIPS 1: Observer=test                User #=    1                       
AIPS 1: Observ. date=08-JAN-2000     Map date=24-NOV-2000               
AIPS 1: # visibilities     23976     Sort order  TB                     
AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  BASELINE  TIME1        
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
AIPS 1: COMPLEX      3   0.0000000e+00       1.00  1.0000000e+00    0.00
AIPS 1: STOKES       1  -1.0000000e+00       1.00 -1.0000000e+00    0.00
AIPS 1: FREQ         1   9.8745000e+10       1.00  1.0240000e+09    0.00
AIPS 1: RA           1    16 50 27.830       1.00       3600.000    0.00
AIPS 1: DEC          1    02 28 58.100       1.00       3600.000    0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 1950.00                                      
AIPS 1: UV weight normalization factor  1.3563e-19                      
AIPS 1: Maximum version number of extension files of type FQ is   1     
AIPS 1: Maximum version number of extension files of type HI is   1     
>tget uvplt   ← UVPLTによりvisibilityデータをいろいろな軸で表示する
>getn 187
AIPS 1: Got(1)   disk= 1  user=   1   type=UV   NGC9876CNT.DBCON.1     
>bchan 0;echan 0;docalib -1
>bparm 6,7,1,130,-130,130,-130 ← plotをu-v planeとし、
                                      軸は+/- 130 kλの範囲でfixed scale。
                                      詳細はUVPLTのon-line help等を参照。
>xinc 2   ← visibilityの数が多い時(1万点以上)は、適宜間引いて表示。
                この例では1個飛ばしにしている 
>inp
AIPS 1: UVPLT     Plots data from a u,v data base: multi-channel version
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID        0                    Data base owner number       
AIPS 1: INNAME     'NGC9876CNT  '          Input UV file name (name)    
AIPS 1: INCLASS    'DBCON '                Input UV file name (class)   
AIPS 1: INSEQ         1                    Input UV file name (seq. #)  
AIPS 1: INDISK        0                    Input UV file disk unit #    
AIPS 1: SOURCES    *all ' '                Sources to plot, ' '=>all.   
AIPS 1: QUAL         -1                    Qualifier -1=>all            
AIPS 1: CALCODE    '    '                  Calibrator code '    '=>all  
AIPS 1: STOKES     '    '                  Stokes type to select.       
AIPS 1: SELBAND      -1                    Bandwidth to select (kHz)    
AIPS 1: SELFREQ      -1                    Frequency to select (MHz)    
AIPS 1: FREQID       -1                    Freq. ID to select.          
AIPS 1: TIMERANG   *all 0                  Time range to select         
AIPS 1: ANTENNAS   *all 0                  Antennas to plot             
AIPS 1: BASELINE   *all 0                  Baselines with ANTENNAS      
AIPS 1: UVRANGE       0           0        UV range in kilolambda.      
AIPS 1: SUBARRAY      0                    Subarray, 0 => all           
AIPS 1: BCHAN         0                    1st spectral channel #       
AIPS 1: ECHAN         0                    Last spectral channel #      
AIPS 1: CHINC         1                    Increment in channel #       
AIPS 1: BIF           0                    Low IF number to plot        
AIPS 1: EIF           0                    Highest IF number to plot    
AIPS 1: DOCALIB      -1                    If >0 calibrate data         
AIPS 1: GAINUSE       0                    CAL (CL or SN) table to apply
AIPS 1: DOPOL        -1                    If >0 correct polarization.  
AIPS 1: BLVER        -1                    BL table to apply.           
AIPS 1: FLAGVER       0                    Flag table version           
AIPS 1: DOBAND       -1                    If >0 apply bandpass cal.    
AIPS 1:                                    Method used depends on value 
AIPS 1:                                    of DOBAND (see HELP file).   
AIPS 1: BPVER        -1                    Bandpass table version       
AIPS 1: SMOOTH     *all 0                  Smoothing function. See      
AIPS 1:                                    HELP SMOOTH for details.     
AIPS 1: XINC          2                    Plot every XINC'th visibility
AIPS 1:                                    0 => 1.                      
AIPS 1: BPARM         6           7        Control parameters           
AIPS 1:               1        -130        1 : X-axis type 0=>UV dist   
AIPS 1:             130        -130        2 : Y-axis type 0=>Ampl      
AIPS 1:             130        *rest 0         1=> amplitude (Jy)       
AIPS 1:                                        2=> phase (degrees)      
AIPS 1:                                        3=> uv dist. (klambda)   
AIPS 1:                                        4=> uv p.a. (deg N->E)   
AIPS 1:                                        5=> time (IAT days)      
AIPS 1:                                        6=> u (klambda)          
AIPS 1:                                        7=> v (klambda)          
AIPS 1:                                        8=> w (klambda)          
AIPS 1:                                        9=> Re(Vis) (Jy)         
AIPS 1:                                        10=> Im(Vis) Jy)         
AIPS 1:                                        11=> time (IAT hours)    
AIPS 1:                                        12=> log(ampl)           
AIPS 1:                                    3 : > 0.0 => fixed scale     
AIPS 1:                                        < 0.0 => fixed range     
AIPS 1:                                    4 : Xmin (fixed scale)       
AIPS 1:                                    5 : Xmax (fixed scale)       
AIPS 1:                                    6 : Ymin (fixed scale)       
AIPS 1:                                    7 : Ymax (fixed scale)       
AIPS 1:                                    8 : Number of bins in plot.  
AIPS 1:                                    9 : > 0 => list bin values.  
AIPS 1:                                    10: > 0 => plot auto-corr too
AIPS 1:                                    BPARM=6,7,2,0 generates      
AIPS 1:                                     square UV coverage plots    
AIPS 1: FACTOR        0                    Scale dots by FACTOR         
AIPS 1: LTYPE         3                    Type of labeling: 1 border,  
AIPS 1:                                    2 no ticks, 3 - 6 standard,  
AIPS 1:                                    7 - 10 only tick labels      
AIPS 1:                                    <0 -> no date/time           
AIPS 1: BADDISK    *all 0                  Disk to avoid for scratch.   
AIPS 1: DOTV         -1                    > 0 Do plot on the TV, else  
AIPS 1:                                    make a plot file             
AIPS 1: GRCHAN        0                    Graphics channel 0 => 1.     
>go uvplt
UVPLT1: Task UVPLT  (release of 15APR99) begins
UVPLT1: FNDPOL: Stokes I computed assuming V=0
UVPLT1: GFINIS: number records used    1132
UVPLT1: PLTUV:      23976 Points plotted
UVPLT1: PLTUV: Plot file version    1  created.
UVPLT1: Appears to have ended successfully
UVPLT1: mpu6m        15APR99 NEW: Cpu=       0.3  Real=       0
AIPS 1: Resumes                                                         
>go tkpl ← Textro画面に表示。ちなみに、printerに出したければgo lwpl。
TKPL 1: Task TKPL   (release of 15APR99) begins
AIPS 1: Resumes                                                         
>TKPL 1: Appears to have ended successfully
TKPL 1: mpu6m        15APR99 NEW: Cpu=       0.2  Real=       5


この例で取り上げるデータのuv coverage。

次に、dirty mapをつくる。

>tget imagr
>getn 187
>outn 'cont-tst'
>outseq 0
>bchan 0;echan 0 ← continuum dataで周波数チャンネルは1つしかない。
                        そこで、begin channelもend channelも0でOK
                        (つまり、全データを使用)。
>npoint 1      ← 像合成に使うチャンネルの数
>cellsize 0.2  ← CELLSIZEは予想されるビームサイズにあわせて
                      調節する。ビームサイズの1/4から1/10が適当。
                      ただし、CELLSIZEを細かくしていくと、当然ながら
                      IMSIZEを大きくとらねばならなくなり、ファイルサイズが
                      巨大化する。

>imsize 512   ← およそ、観測視野の2倍程度の領域をカバーするように
                     決める。この例では、CELLSIZE×IMSIZE=102秒で、
                     観測視野(この周波数で70秒強)を考慮すると、
                     本来ならもう少しIMSIZEを大きくするべきである。
                     ただ、IMSIZEは2のn乗と決まっているので、
                     このケースだと、次は1024まで大きくなってしまう。
                     ファイルサイズ等の関係で1024pixの絵にしたく
                     ない場合は、CELLSIZEを少し大きくすれば良い。

>uvwtf 'na'   ← visibilityのweitingのかけかたを決める。
                    「NA」はnatural weighting。S/Nがそれほど良くない
                    (たとえば10以下)の場合は、このnatural weightingを
                     用いるのが普通。一方、ここをblankにすると、
                     今度はROBUSTというパラメーターの値によって、
                     pure naturalからpure uniformの間の
                     中間的なweightingを実現することができる
                    (ROBUST=5でpure natural、ROBUST=-5でpure uniform)。
                     S/Nが充分よい場合は、ぜひROBUSTパラメーターを
                     振ってみて、高分解能の像合成を試してみるとよい
                    (たとえばUVWTFN=' '、ROBUST=0など)。

>niter 0  ← NITERとは、iteration回数を決めるパラメーター。
                  ここが0になっていると、CLEANは行わず、dirty mapを
                  作る。
>bmaj 0;bmin 0;bpa 0   ← CLEANをしないのでCLEAN beamも指定しない
>flux 0;bcomp 0  ← これもCLEANのときに使うパラメーター。関係ないが
                       ここではいちおう0にしておく。
>inp
AIPS 3: IMAGR: Wide field imaging/Clean task                            
AIPS 3: Adverbs         Values            Comments                      
AIPS 3: ----------------------------------------------------------------
AIPS 3: INNAME     'NGC9876CNT  '          Input UV data (name)         
AIPS 3: INCLASS    'DBCON '                Input UV data (class)        
AIPS 3: INSEQ         1                    Input UV data (seq. #)       
AIPS 3: INDISK        0                    Input UV data disk drive #   
AIPS 3: SOURCES    *all ' '                Source name                  
AIPS 3: QUAL         -1                    Calibrator qualifier -1=>all 
AIPS 3: CALCODE    '    '                  Calibrator code '    '=>all  
AIPS 3: TIMERANG   *all 0                  Time range to use            
AIPS 3: SELBAND      -1                    Bandwidth to select (kHz)    
AIPS 3: SELFREQ      -1                    Frequency to select (MHz)    
AIPS 3: FREQID       -1                    Freq. ID to select.          
AIPS 3: SUBARRAY      0                    Sub-array, 0=>all            
AIPS 3: DOCALIB      -1                    If >0 calibrate data         
AIPS 3: GAINUSE       0                    CL (or SN) table to apply    
AIPS 3: DOPOL        -1                    If >0.5 correct polarization.
AIPS 3: BLVER        -1                    BL table to apply.           
AIPS 3: FLAGVER       0                    Flag table version           
AIPS 3: DOBAND       -1                    If >0.5 apply bandpass cal.  
AIPS 3:                                    Method used depends on value 
AIPS 3:                                    of DOBAND (see HELP file).   
AIPS 3: BPVER        -1                    Bandpass table version       
AIPS 3: SMOOTH     *all 0                  Smoothing function. See      
AIPS 3:                                    HELP SMOOTH for details.     
AIPS 3: STOKES     '    '                  Stokes parameters (see HELP) 
AIPS 3: BCHAN         0                    Low freq. channel 0 for cont.
AIPS 3: ECHAN         0                    Highest freq channel         
AIPS 3: CHANNEL       0                    Restart channel number       
AIPS 3: NPOINTS       1                    Number of chan. to average.  
AIPS 3: CHINC         1                    Channel incr. between maps.  
AIPS 3: BIF           0                    First IF in average.         
AIPS 3: EIF           0                    Last IF in average.          
AIPS 3: OUTNAME    'CONT-TST    '          Output image name (name)     
AIPS 3: OUTDISK       0                    Output image disk drive #    
AIPS 3: OUTSEQ        0                    Output seq. no.              
AIPS 3: OUTVER        1                    CC ver. no (Continuum only)  
AIPS 3:                                    *** SET OUTVER ON RESTARTS   
AIPS 3: IN2NAME    '            '          UV work file name            
AIPS 3: IN2CLASS   '      '                UV work file class           
AIPS 3: IN2SEQ        0                    UV work file seq             
AIPS 3: IN2DISK       0                    UV work file disk            
AIPS 3: CELLSIZE      0.2         0.2      (X,Y) size of grid in asec   
AIPS 3: IMSIZE      512         512        Minimum image size           
AIPS 3: NFIELD        1                    Number of fields (max. 64)   
AIPS 3: DO3DIMAG     -1                    > 0 => use different tangent 
AIPS 3:                                    points for each field        
AIPS 3: FLDSIZE    *all 0                  Size of each field.          
AIPS 3: RASHIFT    *all 0                  RA shift per field (asec)    
AIPS 3: DECSHIFT   *all 0                  DEC shift per field (asec)   
AIPS 3: UVTAPER       0           0        (U,V) Gaussian taper         
AIPS 3:                                      units are kilo-lambda      
AIPS 3: UVRANGE       0           0        Min & max baseline (klambda) 
AIPS 3: GUARD         0           0        x,y guard band fractional    
AIPS 3:                                    radius                       
AIPS 3: ROTATE        0                    Rotate image CCW from N by   
AIPS 3:                                    ROTATE degrees               
AIPS 3: ZEROSP     *all 0                  0-spacing fluxes and weights 
AIPS 3:                                    SEE HELP!!                   
AIPS 3: UVWTFN     'NA'                    UV dist. weight function     
AIPS 3:                                      blank => uniform           
AIPS 3: UVSIZE        0           0        Array size for doing uniform 
AIPS 3:                                    weights.  0 -> actual field  
AIPS 3:                                    size.                        
AIPS 3: ROBUST        0                    Robustness power: -5 -> pure 
AIPS 3:                                    uniform weights, 5 => natural
AIPS 3: UVBOX         0                    Additional rows and columns  
AIPS 3:                                    used in weighting.           
AIPS 3: UVBXFN        1                    Box function type when UVBOX 
AIPS 3:                                    > 0.  0 -> 1 round pill box. 
AIPS 3: XTYPE         5                    Conv. function type in x     
AIPS 3:                                      default spheroidal         
AIPS 3: YTYPE         5                    Conv. function type in y     
AIPS 3:                                      default spheroidal         
AIPS 3: XPARM      *all 0                  Conv. function parms for x   
AIPS 3: YPARM      *all 0                  Conv. function parms for y   
AIPS 3: NITER         0                    Maximum # of Clean components
AIPS 3: BCOMP      *all 0                  Begin at BCOMP component     
AIPS 3:                                    Specify for each field.      
AIPS 3: NBOXES        0                    Number of boxes for Clean    
AIPS 3:                                    NB: field 1 only.            
AIPS 3: CLBOX      *all 0                  Four coordinates for each box
AIPS 3: BOXFILE    *all ' '                Input file of field params   
AIPS 3:                                    and Clean boxes; ' ' => use  
AIPS 3:                                    FLDSIZE, RASHIFT, DECSHIFT,  
AIPS 3:                                    NBOXES, CLBOX only.          
AIPS 3: OBOXFILE   *all ' '                Output file for final Clean  
AIPS 3:                                    boxes                        
AIPS 3: GAIN          0.1                  Clean loop gain              
AIPS 3: FLUX          0                    Minimum Clean component (Jy) 
AIPS 3: MINPATCH     51                    Min. BEAM half-width in AP.  
AIPS 3: BMAJ          0                    FWHM(asec) major axis Clean  
AIPS 3:                                    restoring beam.              
AIPS 3: BMIN          0                    FWHM(asec) minor axis Clean  
AIPS 3:                                    restoring beam.              
AIPS 3: BPA           0                    Clean beam position angle    
AIPS 3: OVERLAP       0                    1 => restore components to   
AIPS 3:                                    overlapped fields, 2=> expect
AIPS 3:                                    overlaps while Cleaning      
AIPS 3: PHAT          0                    Prussian hat height.         
AIPS 3: FACTOR        0                    Speedup factor see HELP      
AIPS 3: CMETHOD    '    '                  Modeling method:             
AIPS 3:                                    'DFT','GRID','    '          
AIPS 3: CPARM      *all 0                  Task enrichment parameters   
AIPS 3:                                    (1) Antenna diameter (m)     
AIPS 3:                                    (2) Source Spectral index    
AIPS 3:                                    (3) Frequency scaling factor 
AIPS 3:                                    (4) >0 => do DFT imaging     
AIPS 3:                                        (not allowed for now)    
AIPS 3:                                    (5) >0 => scale residuals    
AIPS 3:                                    (6) Half-width in x of box   
AIPS 3:                                    (7) Half-width in y of box   
AIPS 3:                                    (10) multiplier of image size
AIPS 3:                                    to get beam size: 0 => 2;    
AIPS 3:                                    2, 1, 0.5 0.25 supported     
AIPS 3: MAXPIXEL      0                    Maximum pixels searched in   
AIPS 3:                                    each major cycle.            
AIPS 3: DOTV         -1                    Display residuals on TV ?    
AIPS 3:                                    Start with field = DOTV      
AIPS 3: BADDISK    *all 0                  Disks to avoid for scratch.  
>

これでパラメーター設定が終わったので、IMAGRを実行。 すると、dirty map、beam、および、work fileの3つのファイルができる。

>go imagr
IMAGR1: Task IMAGR  (release of 15APR99) begins
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: Create NGC9876CNT  .IMAGR .   1 (UV)  on disk  1  cno  188
IMAGR1: Create CONT-TST    .IBEM  .   1 (MA)  on disk  1  cno  189
IMAGR1: Create CONT-TST    .IMAP  .   1 (MA)  on disk  1  cno  190
IMAGR1: Beginning channel    1 through    1 with  1 IFs
IMAGR1: TABLE TYPE AN VERSION   1 DOES NOT EXIST
IMAGR1: PROBLEM OPENING TABLE OBJECT: Temporary AN table for IMACPY
IMAGR1: FAILS to get AN table data for parallactic and zenith angles
IMAGR1: FNDPOL: Stokes I computed assuming V=0
AIPS 1: Resumes                                                         
>IMAGR1: IMACPY: Copied    23976 visibilities to be imaged
IMAGR1: GRDFLT: X and Y convolution type = SPHEROIDAL
IMAGR1: GRDFLT: X and Y parms =  3.0000  1.0000
IMAGR1: GRDFLT: convolution function sampled every 1/100 of a cell
IMAGR1: GRDMEM: Frequency 9.874500e+10 Hz
IMAGR1: Field  1 Sum of gridding weights =  2.54537e+05
IMAGR1: Field  1 Beam min = -311.9 MilliJy, max =    1.0      Jy
IMAGR1: Fit Gaussian FWHM =    2.535 x    2.231      arcsec, PA=  -63.0
IMAGR1: Field  1 min =  -13.4 MilliJy,max =   19.4 MilliJy
IMAGR1: No Cleaning requested
IMAGR1: Checking image max/min
IMAGR1: Appears to have ended successfully
IMAGR1: mpu6m        15APR99 NEW: Cpu=       1.0  Real=       1
>

*.IMAGR というwork fileは、不要なので直ちに消してよい。
*.IBEM がビームパターン、*.IMAPが得られた合成画像である。

>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  188    1 NGC9876CNT  .IMAGR .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  189    1 CONT-TST    .IBEM  .    1 MA 24-NOV-2000 17:45:52     
AIPS 1:  190    1 CONT-TST    .IMAP  .    1 MA 24-NOV-2000 17:45:52     
>getn 189
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT-TST.IBEM.1         
>tvinit   ← AIPSを起動して最初にTV画面を使うときは、
                まずTVINITによりinitializeした方が無難
>tvall  ← 下の説明にある通り、白黒/color切替やzoom/unzoom等ができる。
AIPS 1: Hit button A to enhance B/W or color alternately                
AIPS 1: Hit button B to increment zoom & set zoom center                
AIPS 1: Hit button C to decrement zoom & set zoom center                
AIPS 1: Hit button D to exit                                            
AIPS 1: Cursor X controls intercept                                     
AIPS 1: Cursor Y controls slope                                         
AIPS 1: Cursor X controls position of first contour                     
AIPS 1: Cursor Y controls width of color contours                       
>


得られたビームパターン。ちなみに、この例では、縦軸のtick markが 10秒角である(だいたい70秒角四方を像合成している)。

次に、得られた電波画像(dirty map)をTV画面に表示してみる。

>getn 190
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT-TST.IMAP.1         
>tvinit ← ちなみに、TVALL = TVINIT + TVLOD + TVFIDDLE。
>tvlo     いちいち初期化したくないとき・カラースケールを
>tvfi     保存したい時などは、画面表示の際にTVALLではなくTVLODが便利
AIPS 3: Hit button A to enhance B/W or color alternately                
AIPS 3: Hit button B to increment zoom & set zoom center                
AIPS 3: Hit button C to decrement zoom & set zoom center                
AIPS 3: Hit button D to exit                                            
AIPS 3: Cursor X controls intercept                                     
AIPS 3: Cursor Y controls slope                                         
AIPS 3: Cursor X controls position of first contour                     
AIPS 3: Cursor Y controls width of color contours                                      >


できたdirty map。上のbeamの絵と比べると、 S/Nこそ悪いものの、ほとんど同じパターンであり、 point sourceが見ているのだろう、ということが伺われる。

☆ noise levelを調べる

CLEANを行う際、どこまで深くCLEANをするか、を判断する際に、 noise levelが一つの目安となる(たとえば、noise levelより 1/100も低いレベルまでCLEANしても計算機の無駄)。

>getn 190
AIPS 3: Got(1)   disk= 1  user=   1   type=MA   MERGER1.IMAP.1          
>tvlo
>tget imean
>getn 190
AIPS 3: Got(1)   disk= 1  user=   1   type=MA   MERGER1.IMAP.1          
>blc 0
>trc 0 ←もし画面全面でrmsを出すならこれでGO IMEANする
>tvwin  ←ある領域だけでrmsを調べる場合:
               これでTV画面上にカーソルが出てくるので、
               emission free(と思われる領域)を囲む。
AIPS 3: Set B.L.C. : button A, B, or C to change to T.R.C.              
AIPS 3: Button D to kill and exit                                       
AIPS 3: Set T.R.C. : button A or B to repeat B.L.C.                     
AIPS 3: Button C or D to exit                                           
AIPS 3: BLC =    34.00   27.00    1.00    1.00    1.00    1.00    1.00  
AIPS 3: TRC =   192.00  447.00    1.00    1.00    1.00    1.00    1.00  
>inp imean
AIPS 3: IMEAN:  Task to print the mean, rms and extrema in an image     
AIPS 3: Adverbs         Values            Comments                      
AIPS 3: ----------------------------------------------------------------
AIPS 3: DOHIST       -1                    True (1.0) do histogram plot.
AIPS 3:                                    = 2 => flux on x axis        
AIPS 3: USERID        0                    User ID.  0=>current user    
AIPS 3:                                      32000=>all users           
AIPS 3: INNAME     'CONT-TST    '          Image name (name)            
AIPS 3: INCLASS    'IMAP  '                Image name (class)           
AIPS 3: INSEQ         1                    Image name (seq. #)          
AIPS 3: INDISK        0                    Disk drive #                 
AIPS 3: BLC          34          27        Bottom left corner of image  
AIPS 3:               1           1          0=>entire image            
AIPS 3:               1           1           1                         
AIPS 3: TRC         192         447        Top right corner of image    
AIPS 3:               1           1          0=>entire image            
AIPS 3:               1           1           1                         
AIPS 3: NBOXES        0                    No. of ranges for histogram. 
AIPS 3: PIXRANGE      0           0        Min and max range for hist.  
AIPS 3: FUNCTYPE   '  '                    'LG' => do log10 plot of #   
AIPS 3:                                    samples, else linear         
AIPS 3: PIXAVG        0                    Estimate of mean noise value 
AIPS 3: PIXSTD        0                    Estimate of true noise rms   
AIPS 3:                                       < 0 => don't do one       
AIPS 3:                                       = 0 => 2-passes to get    
AIPS 3: LTYPE         3                    Type of labeling: 1 border,  
AIPS 3:                                    2 no ticks, 3 - 6 standard,  
AIPS 3:                                    7 - 10 only tick labels      
AIPS 3:                                    <0 -> no date/time           
AIPS 3: OUTFILE    *all ' '                Name of output log file,     
AIPS 3:                                    No output to file if blank   
AIPS 3: DOTV         -1                    > 0 Do plot on the TV, else  
AIPS 3:                                    make a plot file             
AIPS 3: GRCHAN        0                    Graphics channel 0 => 1.     
>go imean
IMEAN3: Task IMEAN  (release of 15APR99) begins
IMEAN3: Image= MERGER1     .IMAP  .   1 1   xywind=   34   27  192  447
IMEAN3: Mean and rms found by fitting peak in histogram:
IMEAN3: Mean= 7.7558e-05 Rms= 3.4956e-03  **** from histogram
IMEAN3: Mean and rms found by including all data:
IMEAN3: Mean=-6.9234e-05 Rms= 3.5496e-03 JY/BEAM   over   66939. pixels
IMEAN3: Minimum=-1.2568e-02 at  161   52    1    1
IMEAN3: Skypos: RA 16 50 29.09825  DEC 02 28 17.1001
IMEAN3: Maximum= 1.2566e-02 at  112   51    1    1
IMEAN3: Skypos: RA 16 50 29.75219  DEC 02 28 16.9001
IMEAN3: Skypos: IPOL  98745.000 MHZ
IMEAN3: Appears to have ended successfully
IMEAN3: mpu6m        15APR99 NEW: Cpu=       0.0  Real=       0
AIPS 3: Resumes                                                         
>

これより、この例では、noise levelはおよそ3.5mJy/beamと 求められた。

☆ ビームサイズを知る

CLEANをかけるときに、dirty beamをGaussian beamにおきかえることになるが、 どういうサイズのbeamにおきかえるか、を、あらかじめ 決めておく。厳密にやるには、dirty beamを2次元Gaussian fittingして (task IMFITを用いる)決める。通常は、得られたdirty mapの headerを見て、AIPSが決めた値を持ちればよい。

>imh
AIPS 3: Image=AB1CONT   (MA)         Filename=CONT-TST    .IMAP  .   1  
AIPS 3: Telescope=                                                      
AIPS 3: Observer=test                User #=    1                       
AIPS 3: Observ. date=08-JAN-2000     Map date=18-NOV-2000               
AIPS 3: Minimum=-1.34393536e-02      Maximum= 1.93872396e-02 JY/BEAM    
AIPS 3: ----------------------------------------------------------------
AIPS 3: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
AIPS 3: RA---SIN   512    16 50 27.830     256.00      -0.200000    0.00
AIPS 3: DEC--SIN   512    02 28 58.100     257.00       0.200000    0.00
AIPS 3: FREQ         1   9.8745000e+10       1.00  1.0240000e+09    0.00
AIPS 3: STOKES       1   1.0000000e+00       1.00  1.0000000e+00    0.00
AIPS 3: ----------------------------------------------------------------
AIPS 3: Coordinate equinox 1950.00                                      
AIPS 3: Map type=DIRTY               Number of iterations=       0      
AIPS 3: Conv size=   2.53 X   2.23   Position angle= -63.03             
AIPS 3: Maximum version number of extension files of type CC is   1     
AIPS 3: Maximum version number of extension files of type HI is   1     

これより、以下ではCLEAN beamを2.5×2.2秒(P.A. =-63度)とする (ちなみに、どの桁まで使うかは、趣味の問題)。

☆ いざ、CLEAN開始

IMAGRのパラメーター設定をした最後に、 dirty mapを見ながらCLEAN BOX(どの範囲にrealなemissionがあるかを 領域指定する)を設定するので、TV画面にdirty mapを表示させておいてから tget imagrへ進むこと。

>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  188    1 NGC9876CNT  .IMAGR .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  189    1 CONT-TST    .IBEM  .    1 MA 24-NOV-2000 17:47:00     
AIPS 1:  190    1 CONT-TST    .IMAP  .    1 MA 24-NOV-2000 17:55:52     
>getn 190
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT-TST.IMAP.1         
>tvlo
>
>tget imagr
>getn 187  ← 像合成に用いるvisibility file
>outname 'cont' ← dirty mapとは名前を変えておく。
>outseq 1 ← OUTSEQ=0のときは、ファイル上書きをせず新しいファイルを
                 作ってしまう。CLEANを少しづつ進めていくには、
                 同じファイルに上書きしていってくれないと都合が
                 悪いので、OUTSEQとして0以外の適当な定数を入れておく。
>outver 1 ← これは常に1(一旦1にしたらその後はいじる必要なし)。
>bmaj -2.5  ← 上の操作で調べたbeam sizeを入れる。BMAJ<0だと、
                 CLEAN componentをCLEAN beamに置き換えることはせず、
                 residualのマップを作る。まずは、こうして
                 residualを見ながらCLEANを進めていき、ある程度まで
                 CLEANが進んだら、BMAJを>0にして(この例ならbmaj 2.5として)
                 CLEAN componentの置き換えまで実行し、マップを見ながら
                 さらに(必要があれば)CLEANを行うとよい。
>bmin 2.2
>bpa -63
>niter 500 ← CLEANのiterationを500回で止める。ただし、
               通常は、この次にある「flux」というパラメーターで
               CLEANの深さを制御するので、このNITERは多め(500〜2000)に
               しておけばよい。
>flux 3.5e-3 * 3 ← CLEANをしていったresidualが
                  noise levelの3倍以下になったらCLEANをやめる。   
>dotv -1  ← TV画面の自動更新機能は使わない。
              (色々なれてきたら、試してみるとよい。)
>
>inp
AIPS 1: IMAGR: Wide field imaging/Clean task                            
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME     'NGC9876CNT  '          Input UV data (name)         
AIPS 1: INCLASS    'DBCON '                Input UV data (class)        
AIPS 1: INSEQ         1                    Input UV data (seq. #)       
AIPS 1: INDISK        0                    Input UV data disk drive #   
AIPS 1: SOURCES    *all ' '                Source name                  
AIPS 1: QUAL         -1                    Calibrator qualifier -1=>all 
AIPS 1: CALCODE    '    '                  Calibrator code '    '=>all  
AIPS 1: TIMERANG   *all 0                  Time range to use            
AIPS 1: SELBAND      -1                    Bandwidth to select (kHz)    
AIPS 1: SELFREQ      -1                    Frequency to select (MHz)    
AIPS 1: FREQID       -1                    Freq. ID to select.          
AIPS 1: SUBARRAY      0                    Sub-array, 0=>all            
AIPS 1: DOCALIB      -1                    If >0 calibrate data         
AIPS 1: GAINUSE       0                    CL (or SN) table to apply    
AIPS 1: DOPOL        -1                    If >0.5 correct polarization.
AIPS 1: BLVER        -1                    BL table to apply.           
AIPS 1: FLAGVER       0                    Flag table version           
AIPS 1: DOBAND       -1                    If >0.5 apply bandpass cal.  
AIPS 1:                                    Method used depends on value 
AIPS 1:                                    of DOBAND (see HELP file).   
AIPS 1: BPVER        -1                    Bandpass table version       
AIPS 1: SMOOTH     *all 0                  Smoothing function. See      
AIPS 1:                                    HELP SMOOTH for details.     
AIPS 1: STOKES     '    '                  Stokes parameters (see HELP) 
AIPS 1: BCHAN         0                    Low freq. channel 0 for cont.
AIPS 1: ECHAN         0                    Highest freq channel         
AIPS 1: CHANNEL       0                    Restart channel number       
AIPS 1: NPOINTS       1                    Number of chan. to average.  
AIPS 1: CHINC         1                    Channel incr. between maps.  
AIPS 1: BIF           0                    First IF in average.         
AIPS 1: EIF           0                    Last IF in average.          
AIPS 1: OUTNAME    'CONT        '          Output image name (name)     
AIPS 1: OUTDISK       0                    Output image disk drive #    
AIPS 1: OUTSEQ        1                    Output seq. no.              
AIPS 1: OUTVER        1                    CC ver. no (Continuum only)  
AIPS 1:                                    *** SET OUTVER ON RESTARTS   
AIPS 1: IN2NAME    '            '          UV work file name            
AIPS 1: IN2CLASS   '      '                UV work file class           
AIPS 1: IN2SEQ        0                    UV work file seq             
AIPS 1: IN2DISK       0                    UV work file disk            
AIPS 1: CELLSIZE      0.2         0.2      (X,Y) size of grid in asec   
AIPS 1: IMSIZE      512         512        Minimum image size           
AIPS 1: NFIELD        1                    Number of fields (max. 64)   
AIPS 1: DO3DIMAG     -1                    > 0 => use different tangent 
AIPS 1:                                    points for each field        
AIPS 1: FLDSIZE    *all 0                  Size of each field.          
AIPS 1: RASHIFT    *all 0                  RA shift per field (asec)    
AIPS 1: DECSHIFT   *all 0                  DEC shift per field (asec)   
AIPS 1: UVTAPER       0           0        (U,V) Gaussian taper         
AIPS 1:                                      units are kilo-lambda      
AIPS 1: UVRANGE       0           0        Min & max baseline (klambda) 
AIPS 1: GUARD         0           0        x,y guard band fractional    
AIPS 1:                                    radius                       
AIPS 1: ROTATE        0                    Rotate image CCW from N by   
AIPS 1:                                    ROTATE degrees               
AIPS 1: ZEROSP     *all 0                  0-spacing fluxes and weights 
AIPS 1:                                    SEE HELP!!                   
AIPS 1: UVWTFN     'NA'                    UV dist. weight function     
AIPS 1:                                      blank => uniform           
AIPS 1: UVSIZE        0           0        Array size for doing uniform 
AIPS 1:                                    weights.  0 -> actual field  
AIPS 1:                                    size.                        
AIPS 1: ROBUST        0                    Robustness power: -5 -> pure 
AIPS 1:                                    uniform weights, 5 => natural
AIPS 1: UVBOX         0                    Additional rows and columns  
AIPS 1:                                    used in weighting.           
AIPS 1: UVBXFN        1                    Box function type when UVBOX 
AIPS 1:                                    > 0.  0 -> 1 round pill box. 
AIPS 1: XTYPE         5                    Conv. function type in x     
AIPS 1:                                      default spheroidal         
AIPS 1: YTYPE         5                    Conv. function type in y     
AIPS 1:                                      default spheroidal         
AIPS 1: XPARM      *all 0                  Conv. function parms for x   
AIPS 1: YPARM      *all 0                  Conv. function parms for y   
AIPS 1: NITER       500                    Maximum # of Clean components
AIPS 1: BCOMP      *all 0                  Begin at BCOMP component     
AIPS 1:                                    Specify for each field.      
AIPS 1: NBOXES        1                    Number of boxes for Clean    
AIPS 1:                                    NB: field 1 only.            
AIPS 1: CLBOX        -1           9        Four coordinates for each box
AIPS 1:             254         257        *rest 0                      
AIPS 1: BOXFILE    *all ' '                Input file of field params   
AIPS 1:                                    and Clean boxes; ' ' => use  
AIPS 1:                                    FLDSIZE, RASHIFT, DECSHIFT,  
AIPS 1:                                    NBOXES, CLBOX only.          
AIPS 1: OBOXFILE   *all ' '                Output file for final Clean  
AIPS 1:                                    boxes                        
AIPS 1: GAIN          0.1                  Clean loop gain              
AIPS 1: FLUX          0.0105               Minimum Clean component (Jy) 
AIPS 1: MINPATCH     51                    Min. BEAM half-width in AP.  
AIPS 1: BMAJ         -2.5                  FWHM(asec) major axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BMIN          2.2                  FWHM(asec) minor axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BPA         -63                    Clean beam position angle    
AIPS 1: OVERLAP       0                    1 => restore components to   
AIPS 1:                                    overlapped fields, 2=> expect
AIPS 1:                                    overlaps while Cleaning      
AIPS 1: PHAT          0                    Prussian hat height.         
AIPS 1: FACTOR        0                    Speedup factor see HELP      
AIPS 1: CMETHOD    '    '                  Modeling method:             
AIPS 1:                                    'DFT','GRID','    '          
AIPS 1: CPARM      *all 0                  Task enrichment parameters   
AIPS 1:                                    (1) Antenna diameter (m)     
AIPS 1:                                    (2) Source Spectral index    
AIPS 1:                                    (3) Frequency scaling factor 
AIPS 1:                                    (4) >0 => do DFT imaging     
AIPS 1:                                        (not allowed for now)    
AIPS 1:                                    (5) >0 => scale residuals    
AIPS 1:                                    (6) Half-width in x of box   
AIPS 1:                                    (7) Half-width in y of box   
AIPS 1:                                    (10) multiplier of image size
AIPS 1:                                    to get beam size: 0 => 2;    
AIPS 1:                                    2, 1, 0.5 0.25 supported     
AIPS 1: MAXPIXEL      0                    Maximum pixels searched in   
AIPS 1:                                    each major cycle.            
AIPS 1: DOTV         -1                    Display residuals on TV ?    
AIPS 1:                                    Start with field = DOTV      
AIPS 1: BADDISK    *all 0                  Disks to avoid for scratch.  
>
>tvbox ← TV画面を見ながらCLEAN BOXを指定する。
              要領はTVWINとほぼ一緒だが、異なるのは「箱」だけでなく
             「円」が指定できること。TVBOXと打つと、画面にクロスが
              出てくるが、ここでキーボードのCを打つと、クロスが○に
              変わる。この状態でマウスをドラッグすると、○のサイズが変わる。
              さらにAを押すと、今度は○の位置をずらすことができる。
              
AIPS 3: Setting box number  1                                           
AIPS 3: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 3: Button C to switch between circle and box, D to kill and exit   
AIPS 3: Setting box number  1                                           
AIPS 3: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 3: Button C to switch between circle and box, D to kill and exit   
AIPS 3: Set radius: button A to repeat center                           
AIPS 3: Button B for next box, button C for previous box, D to exit     
AIPS 3: Reset center: buttons as for radius                             
AIPS 3: Setting box number  2                                           
AIPS 3: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 3: Button C to switch between circle and box, D to kill and exit   
AIPS 3: Setting box number  2                                           
AIPS 3: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 3: Button C to switch between circle and box, D to kill and exit   
AIPS 3: Set radius: button A to repeat center                           
AIPS 3: Button B for next box, button C for previous box, D to exit     
AIPS 3: NBOXES reset from  0 to  2                                      
AIPS 3: BOX(  1) =    -1.00    9.00  255.00  255.00                     
AIPS 3: BOX(  2) =    -1.00   10.00  256.00  255.00                     
>tvfi
AIPS 3: Hit button A to enhance B/W or color alternately                
AIPS 3: Hit button B to increment zoom & set zoom center                
AIPS 3: Hit button C to decrement zoom & set zoom center                
AIPS 3: Hit button D to exit                                            
>


強いemissionがある領域を指定した状態(BOX/CIRCLEをかけた状態)。

これで準備完了。IMAGRを実行し、最初のCLEANを行う。 初回のCLEANは、マップ上でもっとも強いピーク付近のみで CLEANを行い、様子を見るのがよい。 この例では、ほとんど点源に見えるので、 CLEAN BOX/CIRCLEは1個のみ (複雑な例は「実行例2」参照)。

>
>go imagr
IMAGR1: Task IMAGR  (release of 15APR99) begins
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: Create NGC9876CNT  .IMAGR .   2 (UV)  on disk  1  cno  191
IMAGR1: Create CONT        .IBEM  .   1 (MA)  on disk  1  cno  192
IMAGR1: Create CONT        .ICLN  .   1 (MA)  on disk  1  cno  193
IMAGR1: Beginning channel    1 through    1 with  1 IFs
IMAGR1: TABLE TYPE AN VERSION   1 DOES NOT EXIST
IMAGR1: PROBLEM OPENING TABLE OBJECT: Temporary AN table for IMACPY
IMAGR1: FAILS to get AN table data for parallactic and zenith angles
IMAGR1: FNDPOL: Stokes I computed assuming V=0
AIPS 1: Resumes                                                         
>IMAGR1: IMACPY: Copied    23976 visibilities to be imaged
IMAGR1: GRDFLT: X and Y convolution type = SPHEROIDAL
IMAGR1: GRDFLT: X and Y parms =  3.0000  1.0000
IMAGR1: GRDFLT: convolution function sampled every 1/100 of a cell
IMAGR1: GRDMEM: Frequency 9.874500e+10 Hz
IMAGR1: Field  1 Sum of gridding weights =  2.54542e+05
IMAGR1: Field  1 Beam min = -289.3 MilliJy, max =    1.0      Jy
IMAGR1: Fit Gaussian FWHM =    2.535 x    2.231      arcsec, PA=  -63.0
IMAGR1: Field  1 min =  -13.4 MilliJy,max =   19.4 MilliJy
IMAGR1: Using 1019 cell dirty beam + residuals >     4.88 MilliJy
IMAGR1:      249 Residual map points loaded
IMAGR1: Reached minimum algorithm flux =  14.258 MilliJy iter=        5
IMAGR1: Total Cleaned flux density    =    8.291 MilliJy        5 comps
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: VISDFT: Model components of type Point
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.9 MilliJy,max =   14.1 MilliJy
IMAGR1: Using 1019 cell dirty beam + residuals >     3.29 MilliJy
IMAGR1:      252 Residual map points loaded
IMAGR1: Reached min. Clean flux density=   9.740 MilliJy iter=       10
IMAGR1: Total Cleaned flux density    =   13.993 MilliJy       10 comps
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.7 MilliJy,max =   14.0 MilliJy
IMAGR1: Peak residual in window   9.448 less than limit  10.500 Milli Jy
IMAGR1: Checking image max/min
IMAGR1: Appears to have ended successfully
IMAGR1: mpu6m        15APR99 NEW: Cpu=       2.6  Real=       3                                                >
>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 18:01:31     
AIPS 1:  188    1 NGC9876CNT  .IMAGR .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  189    1 CONT-TST    .IBEM  .    1 MA 24-NOV-2000 17:47:00     
AIPS 1:  190    1 CONT-TST    .IMAP  .    1 MA 24-NOV-2000 17:58:14     
AIPS 1:  191    1 NGC9876CNT  .IMAGR .    2 UV 24-NOV-2000 18:01:34     
AIPS 1:  192    1 CONT        .IBEM  .    1 MA 24-NOV-2000 18:01:34     
AIPS 1:  193    1 CONT        .ICLN  .    1 MA 24-NOV-2000 18:01:34     
>

今度は*.ICLNというファイルができている。これがCLEANの結果。 ただし、今はBMAJ<0でCLEANのresidualをマップにして示している。 このresidualマップをTV画面に表示させてみよう。

>getn 193
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT.ICLN.1             
>tvlo


というわけで、これがCLEAN1回目の結果。 residual flux = 3 sigmaのところでCLEANを止めている。 このため、redisual mapを見ると、中心付近(BOXをかけたところ)に まだ有意なemissionが残っている。CLEAN componentがいくつまで進んでいるか を確認した後、2回目のCLEANを行う。

どこまでCLEAN componentが進んだか (CLEAN componentがいくつあるか)をみるには、 prtccを使う。

>inp prtc
AIPS 1: PRTCC:  Task to print any clean component table extension files 
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID        0                    Image owner ID number        
AIPS 1: INNAME     'CONT        '          Image name (name)            
AIPS 1: INCLASS    'ICLN  '                Image name (class)           
AIPS 1: INSEQ         1                    Image name (seq. #)          
AIPS 1: INDISK        0                    Disk drive #                 
AIPS 1: INVERS        0                    CC file ver. #               
AIPS 1: BCOUNT        1                    First row number             
AIPS 1: ECOUNT        0                    Last row number              
AIPS 1: XINC          2                    Increment between rows       
AIPS 1: DOCRT        -1                    If > 0, write to CRT         
AIPS 1:                                    > 72 => terminal width       
AIPS 1: OUTPRINT   'DA01:UV6240AVR.DATA                             '   
AIPS 1:                                    Printer disk file to save    
AIPS 1: DOCELL        1                    If > 0, print pos. in cells  
>outp ''
>xinc 1
>docrt 1  ← これをしないと、画面ではなくプリンターにCLEAN compoementの
       羅列が出力されてしまう
>inp prtc
AIPS 1: PRTCC:  Task to print any clean component table extension files 
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID        0                    Image owner ID number        
AIPS 1: INNAME     'CONT        '          Image name (name)            
AIPS 1: INCLASS    'ICLN  '                Image name (class)           
AIPS 1: INSEQ         1                    Image name (seq. #)          
AIPS 1: INDISK        0                    Disk drive #                 
AIPS 1: INVERS        0                    CC file ver. #               
AIPS 1: BCOUNT        1                    First row number             
AIPS 1: ECOUNT        0                    Last row number              
AIPS 1: XINC          0                    Increment between rows       
AIPS 1: DOCRT         1                    If > 0, write to CRT         
AIPS 1:                                    > 72 => terminal width       
AIPS 1: OUTPRINT   '                                                '   
AIPS 1:                                    Printer disk file to save    
AIPS 1: DOCELL        1                    If > 0, print pos. in cells  
>go prtc
PRTCC1: Task PRTCC  (release of 15APR99) begins
PRTCC1: Appears to have ended successfully
PRTCC1: mpu6m        15APR99 NEW: Cpu=       0.0  Real=       1
AIPS 1: Resumes                                                         
>


最初のCLEANを行った際のcc list。10回のCLEANが行われている。

というわけで、CLEAN component 10個までCLEANが進んだので、 この10個めからCLEANを続行する。このとき、CLEANを止める flux levelを落とす。この例では、一気に1 sigmaレベルまで 落とす。また、residualのemissonをうまくCLEANできるように、 BOX(この例ではCIRCLEだが)をかけなおしたり、追加したりする。

>tvfi
AIPS 1: Hit button A to enhance B/W or color alternately                
AIPS 1: Hit button B to increment zoom & set zoom center                
AIPS 1: Hit button C to decrement zoom & set zoom center                
AIPS 1: Hit button D to exit                                            
>tget imagr
>bcomp 10
>flux = flux/3  ← さっきまで3シグマだったので、こうタイプすると
                      1シグマの値がfluxに入るはず。
>type flux     ← いちおう、flux値を確認。
AIPS 1:       0.0035     ←  OK。                                         
>tvbox ← boxをかける。
AIPS 1: Setting box number  1                                           
AIPS 1: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 1: Button C to switch between circle and box, D to kill and exit   
AIPS 1: Setting box number  1                                           
AIPS 1: Set B.L.C. : button A or B to change to T.R.C.                  
AIPS 1: Button C to switch between circle and box, D to kill and exit   
AIPS 1: Set radius: button A to repeat center                           
AIPS 1: Button B for next box, button C for previous box, D to exit     
AIPS 1: Reset center: buttons as for radius                             
AIPS 1: Reset radius                                                    
AIPS 1: Reset center: buttons as for radius                             
AIPS 1: Reset radius                                                    
AIPS 1: Reset center: buttons as for radius                             
AIPS 1: BOX(  1) =    -1.00   10.00  255.00  257.00                     
>inp
AIPS 1: IMAGR: Wide field imaging/Clean task                            
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME     'NGC9876CNT  '          Input UV data (name)         
AIPS 1: INCLASS    'DBCON '                Input UV data (class)        
AIPS 1: INSEQ         1                    Input UV data (seq. #)       
AIPS 1: INDISK        0                    Input UV data disk drive #   
AIPS 1: SOURCES    *all ' '                Source name                  
AIPS 1: QUAL         -1                    Calibrator qualifier -1=>all 
AIPS 1: CALCODE    '    '                  Calibrator code '    '=>all  
AIPS 1: TIMERANG   *all 0                  Time range to use            
AIPS 1: SELBAND      -1                    Bandwidth to select (kHz)    
AIPS 1: SELFREQ      -1                    Frequency to select (MHz)    
AIPS 1: FREQID       -1                    Freq. ID to select.          
AIPS 1: SUBARRAY      0                    Sub-array, 0=>all            
AIPS 1: DOCALIB      -1                    If >0 calibrate data         
AIPS 1: GAINUSE       0                    CL (or SN) table to apply    
AIPS 1: DOPOL        -1                    If >0.5 correct polarization.
AIPS 1: BLVER        -1                    BL table to apply.           
AIPS 1: FLAGVER       0                    Flag table version           
AIPS 1: DOBAND       -1                    If >0.5 apply bandpass cal.  
AIPS 1:                                    Method used depends on value 
AIPS 1:                                    of DOBAND (see HELP file).   
AIPS 1: BPVER        -1                    Bandpass table version       
AIPS 1: SMOOTH     *all 0                  Smoothing function. See      
AIPS 1:                                    HELP SMOOTH for details.     
AIPS 1: STOKES     '    '                  Stokes parameters (see HELP) 
AIPS 1: BCHAN         0                    Low freq. channel 0 for cont.
AIPS 1: ECHAN         0                    Highest freq channel         
AIPS 1: CHANNEL       0                    Restart channel number       
AIPS 1: NPOINTS       1                    Number of chan. to average.  
AIPS 1: CHINC         1                    Channel incr. between maps.  
AIPS 1: BIF           0                    First IF in average.         
AIPS 1: EIF           0                    Last IF in average.          
AIPS 1: OUTNAME    'CONT        '          Output image name (name)     
AIPS 1: OUTDISK       0                    Output image disk drive #    
AIPS 1: OUTSEQ        1                    Output seq. no.              
AIPS 1: OUTVER        1                    CC ver. no (Continuum only)  
AIPS 1:                                    *** SET OUTVER ON RESTARTS   
AIPS 1: IN2NAME    '            '          UV work file name            
AIPS 1: IN2CLASS   '      '                UV work file class           
AIPS 1: IN2SEQ        0                    UV work file seq             
AIPS 1: IN2DISK       0                    UV work file disk            
AIPS 1: CELLSIZE      0.2         0.2      (X,Y) size of grid in asec   
AIPS 1: IMSIZE      512         512        Minimum image size           
AIPS 1: NFIELD        1                    Number of fields (max. 64)   
AIPS 1: DO3DIMAG     -1                    > 0 => use different tangent 
AIPS 1:                                    points for each field        
AIPS 1: FLDSIZE    *all 0                  Size of each field.          
AIPS 1: RASHIFT    *all 0                  RA shift per field (asec)    
AIPS 1: DECSHIFT   *all 0                  DEC shift per field (asec)   
AIPS 1: UVTAPER       0           0        (U,V) Gaussian taper         
AIPS 1:                                      units are kilo-lambda      
AIPS 1: UVRANGE       0           0        Min & max baseline (klambda) 
AIPS 1: GUARD         0           0        x,y guard band fractional    
AIPS 1:                                    radius                       
AIPS 1: ROTATE        0                    Rotate image CCW from N by   
AIPS 1:                                    ROTATE degrees               
AIPS 1: ZEROSP     *all 0                  0-spacing fluxes and weights 
AIPS 1:                                    SEE HELP!!                   
AIPS 1: UVWTFN     'NA'                    UV dist. weight function     
AIPS 1:                                      blank => uniform           
AIPS 1: UVSIZE        0           0        Array size for doing uniform 
AIPS 1:                                    weights.  0 -> actual field  
AIPS 1:                                    size.                        
AIPS 1: ROBUST        0                    Robustness power: -5 -> pure 
AIPS 1:                                    uniform weights, 5 => natural
AIPS 1: UVBOX         0                    Additional rows and columns  
AIPS 1:                                    used in weighting.           
AIPS 1: UVBXFN        1                    Box function type when UVBOX 
AIPS 1:                                    > 0.  0 -> 1 round pill box. 
AIPS 1: XTYPE         5                    Conv. function type in x     
AIPS 1:                                      default spheroidal         
AIPS 1: YTYPE         5                    Conv. function type in y     
AIPS 1:                                      default spheroidal         
AIPS 1: XPARM      *all 0                  Conv. function parms for x   
AIPS 1: YPARM      *all 0                  Conv. function parms for y   
AIPS 1: NITER       500                    Maximum # of Clean components
AIPS 1: BCOMP        10          10        Begin at BCOMP component     
AIPS 1:              10          10        Specify for each field.      
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1:              10          10          10          10             
AIPS 1: NBOXES        1                    Number of boxes for Clean    
AIPS 1:                                    NB: field 1 only.            
AIPS 1: CLBOX        -1          10        Four coordinates for each box
AIPS 1:             255         257        *rest 0                      
AIPS 1: BOXFILE    *all ' '                Input file of field params   
AIPS 1:                                    and Clean boxes; ' ' => use  
AIPS 1:                                    FLDSIZE, RASHIFT, DECSHIFT,  
AIPS 1:                                    NBOXES, CLBOX only.          
AIPS 1: OBOXFILE   *all ' '                Output file for final Clean  
AIPS 1:                                    boxes                        
AIPS 1: GAIN          0.1                  Clean loop gain              
AIPS 1: FLUX          0.0035               Minimum Clean component (Jy) 
AIPS 1: MINPATCH     51                    Min. BEAM half-width in AP.  
AIPS 1: BMAJ         -2.5                  FWHM(asec) major axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BMIN          2.2                  FWHM(asec) minor axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BPA         -63                    Clean beam position angle    
AIPS 1: OVERLAP       0                    1 => restore components to   
AIPS 1:                                    overlapped fields, 2=> expect
AIPS 1:                                    overlaps while Cleaning      
AIPS 1: PHAT          0                    Prussian hat height.         
AIPS 1: FACTOR        0                    Speedup factor see HELP      
AIPS 1: CMETHOD    '    '                  Modeling method:             
AIPS 1:                                    'DFT','GRID','    '          
AIPS 1: CPARM      *all 0                  Task enrichment parameters   
AIPS 1:                                    (1) Antenna diameter (m)     
AIPS 1:                                    (2) Source Spectral index    
AIPS 1:                                    (3) Frequency scaling factor 
AIPS 1:                                    (4) >0 => do DFT imaging     
AIPS 1:                                        (not allowed for now)    
AIPS 1:                                    (5) >0 => scale residuals    
AIPS 1:                                    (6) Half-width in x of box   
AIPS 1:                                    (7) Half-width in y of box   
AIPS 1:                                    (10) multiplier of image size
AIPS 1:                                    to get beam size: 0 => 2;    
AIPS 1:                                    2, 1, 0.5 0.25 supported     
AIPS 1: MAXPIXEL      0                    Maximum pixels searched in   
AIPS 1:                                    each major cycle.            
AIPS 1: DOTV         -1                    Display residuals on TV ?    
AIPS 1:                                    Start with field = DOTV      
AIPS 1: BADDISK    *all 0                  Disks to avoid for scratch.  
>go imagr
IMAGR1: Task IMAGR  (release of 15APR99) begins
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: Create NGC9876CNT  .IMAGR .   3 (UV)  on disk  1  cno  194
IMAGR1: Beginning channel    1 through    1 with  1 IFs
IMAGR1: TABLE TYPE AN VERSION   1 DOES NOT EXIST
IMAGR1: PROBLEM OPENING TABLE OBJECT: Temporary AN table for IMACPY
IMAGR1: FAILS to get AN table data for parallactic and zenith angles
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: IMACPY: Copied    23976 visibilities to be imaged
AIPS 1: Resumes                                                         
>IMAGR1: GRDFLT: X and Y convolution type = SPHEROIDAL
IMAGR1: GRDFLT: X and Y parms =  3.0000  1.0000
IMAGR1: GRDFLT: convolution function sampled every 1/100 of a cell
IMAGR1: GRDMEM: Frequency 9.874500e+10 Hz
IMAGR1: Field  1 Sum of gridding weights =  2.54542e+05
IMAGR1: Field  1 Beam min = -289.3 MilliJy, max =    1.0      Jy
IMAGR1: Fit Gaussian FWHM =    2.535 x    2.231      arcsec, PA=  -63.0
IMAGR1: Restarting Clean at       10 components
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: VISDFT: Model components of type Point
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.7 MilliJy,max =   14.0 MilliJy
IMAGR1: Using 1019 cell dirty beam + residuals >     2.38 MilliJy
IMAGR1:      314 Residual map points loaded
IMAGR1: Reached minimum algorithm flux =   4.491 MilliJy iter=       28
IMAGR1: Total Cleaned flux density    =   25.756 MilliJy       28 comps
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.3 MilliJy,max =   14.0 MilliJy
IMAGR1: Using 1019 cell dirty beam + residuals >     1.11 MilliJy
IMAGR1:      308 Residual map points loaded
IMAGR1: Reached min. Clean flux density=   3.319 MilliJy iter=       36
IMAGR1: Total Cleaned flux density    =   28.810 MilliJy       36 comps
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.2 MilliJy,max =   14.0 MilliJy
IMAGR1: Peak residual in window   3.196 less than limit   3.500 Milli Jy
IMAGR1: Checking image max/min
IMAGR1: Appears to have ended successfully
IMAGR1: mpu6m        15APR99 NEW: Cpu=       2.7  Real=       2
>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 18:22:50     
AIPS 1:  188    1 NGC9876CNT  .IMAGR .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  189    1 CONT-TST    .IBEM  .    1 MA 24-NOV-2000 17:47:00     
AIPS 1:  190    1 CONT-TST    .IMAP  .    1 MA 24-NOV-2000 17:58:14     
AIPS 1:  191    1 NGC9876CNT  .IMAGR .    2 UV 24-NOV-2000 18:01:34     
AIPS 1:  192    1 CONT        .IBEM  .    1 MA 24-NOV-2000 18:22:52     
AIPS 1:  193    1 CONT        .ICLN  .    1 MA 24-NOV-2000 18:22:52     
AIPS 1:  194    1 NGC9876CNT  .IMAGR .    3 UV 24-NOV-2000 18:22:52     
>getn 193
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT.ICLN.1             
>tvlo
>

2回目のCLEANを行った結果、得られたresidual map。 深いレベル(1sigma)まで CLEANを行ったので、 BOX(CIRCLE)をかけた領域にはほとんどemissionは 残っていない。


上のresidual mapの拡大。

residualが充分低いレベルまで落ちたと思ったら、 CLEAN componentをrestoreして、CLEANした結果のマップをつくる。 それには、NITER=BCOMPとして (これにより、もうこれ以上CLEANは進まない)、かつ、 BMAJ>0にすればよい。

>go prtc
PRTCC1: Task PRTCC  (release of 15APR99) begins
PRTCC1: Appears to have ended successfully
PRTCC1: mpu6m        15APR99 NEW: Cpu=       0.0  Real=       0
AIPS 1: Resumes                                                         
>


2回目のCLEANをした結果得られたCLEAN compomentのリスト。 1回目(10個)から引き続きCLEANを進め、その結果36個まで 繰り返したところで、CLEANの終了条件(FLUX値で決まっている) に達したことが分かる。

>niter 36  
>bcomp 36  ← niter=bcompなので、もうこれ以上CLEANは進まない
>bmaj = bmaj * -1   ← bmaj>0にしたので、今度はrestoreを行う
>inp
AIPS 1: IMAGR: Wide field imaging/Clean task                            
AIPS 1: Adverbs         Values            Comments                      
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME     'AB4OBJU     '          Input UV data (name)         
AIPS 1: INCLASS    'UVDATA'                Input UV data (class)        
AIPS 1: INSEQ         1                    Input UV data (seq. #)       
AIPS 1: INDISK        0                    Input UV data disk drive #   
AIPS 1: SOURCES    *all ' '                Source name                  
AIPS 1: QUAL         -1                    Calibrator qualifier -1=>all 
AIPS 1: CALCODE    '    '                  Calibrator code '    '=>all  
AIPS 1: TIMERANG   *all 0                  Time range to use            
AIPS 1: SELBAND      -1                    Bandwidth to select (kHz)    
AIPS 1: SELFREQ      -1                    Frequency to select (MHz)    
AIPS 1: FREQID       -1                    Freq. ID to select.          
AIPS 1: SUBARRAY      0                    Sub-array, 0=>all            
AIPS 1: DOCALIB      -1                    If >0 calibrate data         
AIPS 1: GAINUSE       0                    CL (or SN) table to apply    
AIPS 1: DOPOL        -1                    If >0.5 correct polarization.
AIPS 1: BLVER        -1                    BL table to apply.           
AIPS 1: FLAGVER       0                    Flag table version           
AIPS 1: DOBAND       -1                    If >0.5 apply bandpass cal.  
AIPS 1:                                    Method used depends on value 
AIPS 1:                                    of DOBAND (see HELP file).   
AIPS 1: BPVER        -1                    Bandpass table version       
AIPS 1: SMOOTH     *all 0                  Smoothing function. See      
AIPS 1:                                    HELP SMOOTH for details.     
AIPS 1: STOKES     '    '                  Stokes parameters (see HELP) 
AIPS 1: BCHAN         0                    Low freq. channel 0 for cont.
AIPS 1: ECHAN         0                    Highest freq channel         
AIPS 1: CHANNEL       0                    Restart channel number       
AIPS 1: NPOINTS       1                    Number of chan. to average.  
AIPS 1: CHINC         1                    Channel incr. between maps.  
AIPS 1: BIF           0                    First IF in average.         
AIPS 1: EIF           0                    Last IF in average.          
AIPS 1: OUTNAME    'CONT        '          Output image name (name)     
AIPS 1: OUTDISK       0                    Output image disk drive #    
AIPS 1: OUTSEQ        1                    Output seq. no.              
AIPS 1: OUTVER        1                    CC ver. no (Continuum only)  
AIPS 1:                                    *** SET OUTVER ON RESTARTS   
AIPS 1: IN2NAME    '            '          UV work file name            
AIPS 1: IN2CLASS   '      '                UV work file class           
AIPS 1: IN2SEQ        0                    UV work file seq             
AIPS 1: IN2DISK       0                    UV work file disk            
AIPS 1: CELLSIZE      0.2         0.2      (X,Y) size of grid in asec   
AIPS 1: IMSIZE      512         512        Minimum image size           
AIPS 1: NFIELD        1                    Number of fields (max. 64)   
AIPS 1: DO3DIMAG     -1                    > 0 => use different tangent 
AIPS 1:                                    points for each field        
AIPS 1: FLDSIZE    *all 0                  Size of each field.          
AIPS 1: RASHIFT    *all 0                  RA shift per field (asec)    
AIPS 1: DECSHIFT   *all 0                  DEC shift per field (asec)   
AIPS 1: UVTAPER       0           0        (U,V) Gaussian taper         
AIPS 1:                                      units are kilo-lambda      
AIPS 1: UVRANGE       0           0        Min & max baseline (klambda) 
AIPS 1: GUARD         0           0        x,y guard band fractional    
AIPS 1:                                    radius                       
AIPS 1: ROTATE        0                    Rotate image CCW from N by   
AIPS 1:                                    ROTATE degrees               
AIPS 1: ZEROSP     *all 0                  0-spacing fluxes and weights 
AIPS 1:                                    SEE HELP!!                   
AIPS 1: UVWTFN     'NA'                    UV dist. weight function     
AIPS 1:                                      blank => uniform           
AIPS 1: UVSIZE        0           0        Array size for doing uniform 
AIPS 1:                                    weights.  0 -> actual field  
AIPS 1:                                    size.                        
AIPS 1: ROBUST        0                    Robustness power: -5 -> pure 
AIPS 1:                                    uniform weights, 5 => natural
AIPS 1: UVBOX         0                    Additional rows and columns  
AIPS 1:                                    used in weighting.           
AIPS 1: UVBXFN        1                    Box function type when UVBOX 
AIPS 1:                                    > 0.  0 -> 1 round pill box. 
AIPS 1: XTYPE         5                    Conv. function type in x     
AIPS 1:                                      default spheroidal         
AIPS 1: YTYPE         5                    Conv. function type in y     
AIPS 1:                                      default spheroidal         
AIPS 1: XPARM      *all 0                  Conv. function parms for x   
AIPS 1: YPARM      *all 0                  Conv. function parms for y   
AIPS 1: NITER        36                    Maximum # of Clean components
AIPS 1: BCOMP        36          36        Begin at BCOMP component     
AIPS 1:              36          36        Specify for each field.      
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1:              36          36          36          36             
AIPS 1: NBOXES        1                    Number of boxes for Clean    
AIPS 1:                                    NB: field 1 only.            
AIPS 1: CLBOX        -1          10        Four coordinates for each box
AIPS 1:             255         257        *rest 0                      
AIPS 1: BOXFILE    *all ' '                Input file of field params   
AIPS 1:                                    and Clean boxes; ' ' => use  
AIPS 1:                                    FLDSIZE, RASHIFT, DECSHIFT,  
AIPS 1:                                    NBOXES, CLBOX only.          
AIPS 1: OBOXFILE   *all ' '                Output file for final Clean  
AIPS 1:                                    boxes                        
AIPS 1: GAIN          0.1                  Clean loop gain              
AIPS 1: FLUX          0.0035               Minimum Clean component (Jy) 
AIPS 1: MINPATCH     51                    Min. BEAM half-width in AP.  
AIPS 1: BMAJ          2.5                  FWHM(asec) major axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BMIN          2.2                  FWHM(asec) minor axis Clean  
AIPS 1:                                    restoring beam.              
AIPS 1: BPA         -63                    Clean beam position angle    
AIPS 1: OVERLAP       0                    1 => restore components to   
AIPS 1:                                    overlapped fields, 2=> expect
AIPS 1:                                    overlaps while Cleaning      
AIPS 1: PHAT          0                    Prussian hat height.         
AIPS 1: FACTOR        0                    Speedup factor see HELP      
AIPS 1: CMETHOD    '    '                  Modeling method:             
AIPS 1:                                    'DFT','GRID','    '          
AIPS 1: CPARM      *all 0                  Task enrichment parameters   
AIPS 1:                                    (1) Antenna diameter (m)     
AIPS 1:                                    (2) Source Spectral index    
AIPS 1:                                    (3) Frequency scaling factor 
AIPS 1:                                    (4) >0 => do DFT imaging     
AIPS 1:                                        (not allowed for now)    
AIPS 1:                                    (5) >0 => scale residuals    
AIPS 1:                                    (6) Half-width in x of box   
AIPS 1:                                    (7) Half-width in y of box   
AIPS 1:                                    (10) multiplier of image size
AIPS 1:                                    to get beam size: 0 => 2;    
AIPS 1:                                    2, 1, 0.5 0.25 supported     
AIPS 1: MAXPIXEL      0                    Maximum pixels searched in   
AIPS 1:                                    each major cycle.            
AIPS 1: DOTV         -1                    Display residuals on TV ?    
AIPS 1:                                    Start with field = DOTV      
AIPS 1: BADDISK    *all 0                  Disks to avoid for scratch.  
>
>go imagr
IMAGR1: Task IMAGR  (release of 15APR99) begins
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: Create NGC9876CNT  .IMAGR .   4 (UV)  on disk  1  cno  195
IMAGR1: Beginning channel    1 through    1 with  1 IFs
IMAGR1: TABLE TYPE AN VERSION   1 DOES NOT EXIST
IMAGR1: PROBLEM OPENING TABLE OBJECT: Temporary AN table for IMACPY
IMAGR1: FAILS to get AN table data for parallactic and zenith angles
IMAGR1: FNDPOL: Stokes I computed assuming V=0
IMAGR1: IMACPY: Copied    23976 visibilities to be imaged
AIPS 1: Resumes                                                         
>IMAGR1: GRDFLT: X and Y convolution type = SPHEROIDAL
IMAGR1: GRDFLT: X and Y parms =  3.0000  1.0000
IMAGR1: GRDFLT: convolution function sampled every 1/100 of a cell
IMAGR1: GRDMEM: Frequency 9.874500e+10 Hz
IMAGR1: Field  1 Sum of gridding weights =  2.54542e+05
IMAGR1: Field  1 Beam min = -289.3 MilliJy, max =    1.0      Jy
IMAGR1: Fit Gaussian FWHM =    2.535 x    2.231      arcsec, PA=  -63.0
IMAGR1: Restarting Clean at       36 components
IMAGR1: VISDFT: Begin DFT component subtraction
IMAGR1: VISDFT: Model components of type Point
IMAGR1: I Polarization data processed
IMAGR1: Field  1 min =  -12.2 MilliJy,max =   14.0 MilliJy
IMAGR1: Total Clean components       36 reaches limit      36
IMAGR1: Peak residual in window   3.196 less than limit   3.500 Milli Jy
IMAGR1: Restoring Clean components
IMAGR1: Checking image max/min
IMAGR1: Appears to have ended successfully
IMAGR1: mpu6m        15APR99 NEW: Cpu=       2.3  Real=       2
>
>pcat
AIPS 1: Catalog on disk  1                                              
AIPS 1:  Cat Usid Mapname      Class   Seq  Pt     Last access      Stat
AIPS 1:  187    1 NGC9876CNT  .DBCON .    1 UV 24-NOV-2000 18:32:34     
AIPS 1:  188    1 NGC9876CNT  .IMAGR .    1 UV 24-NOV-2000 17:45:52     
AIPS 1:  189    1 CONT-TST    .IBEM  .    1 MA 24-NOV-2000 17:47:00     
AIPS 1:  190    1 CONT-TST    .IMAP  .    1 MA 24-NOV-2000 17:58:14     
AIPS 1:  191    1 NGC9876CNT  .IMAGR .    2 UV 24-NOV-2000 18:01:34     
AIPS 1:  192    1 CONT        .IBEM  .    1 MA 24-NOV-2000 18:32:36     
AIPS 1:  193    1 CONT        .ICLN  .    1 MA 24-NOV-2000 18:32:49     
AIPS 1:  194    1 NGC9876CNT  .IMAGR .    3 UV 24-NOV-2000 18:22:52     
AIPS 1:  195    1 NGC9876CNT  .IMAGR .    4 UV 24-NOV-2000 18:32:40     
>getn 193
AIPS 1: Got(1)   disk= 1  user=   1   type=MA   CONT.ICLN.1             
>tvlo
>tvfi
AIPS 1: Hit button A to enhance B/W or color alternately                
AIPS 1: Hit button B to increment zoom & set zoom center                
AIPS 1: Hit button C to decrement zoom & set zoom center                
AIPS 1: Hit button D to exit                                            
AIPS 1: Cursor X controls intercept                                     
AIPS 1: Cursor Y controls slope                                         
AIPS 1: Cursor X controls position of first contour                     
AIPS 1: Cursor Y controls width of color contours                       
AIPS 1: Cursor X controls intercept                                     
AIPS 1: Cursor Y controls slope                                         
AIPS 1: Cursor X controls position of first contour                     
AIPS 1: Cursor Y controls width of color contours                       
>

というわけで、CLEAN画像が得られた。


CLEANされたマップ。最初のdirty mapと比較してみると、 side lobe pattern(beam pattern)が取り除かれ、 視野中心にある点源だけがリアルだったことが分かる。 このあと、emissionの強度によっては、 さらに低いレベルまで(たとえば0.5 sigmaとか)CLEANを 続行することもある(特にemissionが非常に強い(100 sigmaとか)場合は、 side lobeといえどもかなりの強度になるので、 かなり低いレベルまでCLEANする必要が出てくる。


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last updated: Friday, 24-Nov-2000 19:55:53 JST
ご意見・質問は nma@nro.nao.ac.jp