The efficiencies of the 45m radiotelescope 2001

Effective for period between Nov. 2001 - June. 2002 (Measured between Oct. 2001 and Nov. 2001)

*Based on the measurements in Nov. 2002 only at high frequency (115 GHz), the following measured values were judged to be effective till June 2003.

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Receiver  Frequency   HPBW     Aperture    Main beam  Calib.     EL.   comment
            (GHz)   (arcsec)   effic(%)    effic(%)   source
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H22(ch1)     23     73.2+-0.2   63+-4      84+-5     NGC7027     62-55
   (ch2)     23     72.4  0.1   62  3      81  4     NGC7027     62-55
H30          32     51.6  0.1   61  3      79  3     Saturn      64-68  
                                                     3C454.3     70-70        
H40          --     ----  ---    ---        ---      -----  
S40          43     38.4  0.1   60  3      77  3     Saturn      60-64   a
                                                     3C454.3     42-37
             49     35.0  0.3   53  2      73  3     Saturn      72-68   a
                                                     3C273       46-50
S80          86     18.5  0.1   41  2      49  2     Saturn      70-67
                                                     3C273       43-48
            100     16.1  0.1   39  4      47  4     Saturn      45-50
                                                     3C279       31-34
            115     14.8  0.1   23  2      32  3     Saturn      70-72
                                                     3C279       30-36
S100         86     18.2  0.1   44  2      51  2     Saturn      70-67
                                                     3C273       43-48
            100     16.1  0.1   42  4      52  4     Saturn      45-50
                                                     3C279       31-34
            115     14.8  0.1   29  3      40  3     Saturn      70-72
                                                     3C279       30-36
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a: The beam sizes of the S40 receiver at 43 and 49 GHz are 
elongated for about 3.5 and 5.1 arcsec, respectively, in elevation.
The beam size in the table is the average of the values in azimuth 
and elevation scans.

The error of the efficiencies is mainly due to uncertainty of brightness temperature of the planet or flux density of NGC 7027. The error of the efficiencies and beam sizes corresponds to one sigma.

Brightness Temperatures and Flux Density of Sources
- Saturn
  - 115 GHz 155+-11 K (Interpolation of the values at 2.1 mm and 3.1 mm)
  - 100 GHz 148+-11 K
  - 86 GHz 153+-5 K
  - 49 GHz 144+-5 K (Interpolation of the values at 3.5 mm and 9.6 mm)
  - 43 GHz 142+-5 K (Interpolation of the values at 3.5 mm and 9.6 mm)
  - 32 GHz 134+-5 K (Interpolation of the values at 3.5 mm and 9.6 mm)
  We mainly used temperatures compiled by Shibata (1990). The error corresponds to one sigma. The brightness temperature of Saturn is reported to possibly increase about 10 %, when the inclination of the ring viewed from the Earth becomes large (Ulich 1981). This tendency is seen, when the inclination angle is larger than 23 deg. The inclination during our measurement period was about 26 deg (Astronomical Almanac, F41 & L11, B: Saturnicentric latitude of the Earth). However, this tendency does not seem to be well established. We, therefore, are not taking into account of this effect.
- NGC 7027
  - As a flux density at 23 GHz, we used 5.86 Jy (estimated by Baars et al. 1977 at 22.235 GHz). The error (absolute accuracy) was estimated to be 5 %.
Diameter of the Planet
- Diameters of the planet are taken from Japanese Ephemeris. In the case of Saturn, the diameters in the polar and equatorial directions are significantly different. In Japanese Ephemeris, only the radius in the polar direction is listed. Therefore, a correction is done with the ratio (1.12) of the diameters in the two directions. The effective diameter is calculated with a formula below:
  2 x (1.12 x polar radius x polar radius) ^ 0.5.
Comments on the Results of This Period
- In autumn 2001 beam sizes and efficiencies at 115 GHz were measured for the first time. The obtained values will be helpful for observations with the 12CO line.
  Generally, the beam sizes and efficiencies obtained are similar to the corresponding values of the last period (autumn 2000).
References
- Baars et al. Astron.&Astrophys., 61, 99 (1977)
- Shibata, Internal Memorandum: Brightness temperatures of Venus, Mars, and Saturn (1990)
- Ulich, Astron. J., 86, 1619 (1981)
- Astronomical Almanac (2001)
- Japanese Ephemeris, Maritime Safety Agency of Japan (2001)

Appendix

2006-12-08 nro45mrt @ NRO