Last Update: 25th December 2018


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[Continuum Observation] | Source Tab (Cont.) | Reference Tab (Cont.) | Scan Tab (Cont.) | Device Tab (Cont.) |

Scan Tab (Line)

The scan table prescribes the movement of the Nobeyama 45-m telescope. The Nobeyama 45-m telescope can observe the target object with 5 different scan patterns: Single Point, On-On, On-the-Fly, Cross Point, and Multi Point. The Scan Tab helps you to make the scan table easily.

nobs: Scan Tab


Scan Table [mandatory field]

Enter a name for the scan table. A configuration file will be saved under your working directory with the name of

<the name of the Scan Table you defined>.nscan

The limitations of a filename of the scan table are as follows:

NOTE: You can save the input parameters anytime you want (the nobs allows you to save the scan table even if some mandatory fields still blank). The nobs does not check whether these input parameters follow the rules at that time.

Click the Check button for a basic check of the parameters. This feature only checks for simple typos, and it is not meant for checking the details of the observational setup.

In order to check on-source positions for OTF mode, it is useful to utilise a tool named obspoint. This tool generates the positions of the on-source defined in your scan table.

Note (optional)

You can use this space to leave any memo about the scan table. A character limit is 100, and a line break is prohibited.

Scan Pattern

There are 5 different scan patterns. Select the scan pattern you intend to use from the pull-down menu located at the upper-right corner or each tab. The scan tab will switch to the corresponding scan pattern.

Single Point

'Single Point' scan is a standard single-point scan with a position-switch method.

nobs: Scan Tab: Single Point mode

Scan Parameters

Calibration

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On-On

The On-On mode is a unique observing mode for multi-beam receiver. Hence this mode must be used in conjunction with the FOREST receiver.
nobs: Scan Tab: On-On mode

When the On-On observation is performed, the FOREST Beam 1 points to the on-position, while the other beam, the FOREST Beam 3, points to the off-position located 70" (corresponds a beam separation of FOREST Beam 1 and Beam 3) away from the source coordinates. When a single integration is done, then the telescope moves so that the FOREST Beam beam is now pointed toward the on-position. Thus, the user who is going to perform the On-On scan mode should previously know that the source is compact enough.
FOREST beam distribution for On-On mode
FOREST Beams used in the On-On mode

Sequence Pattern for On-On mode
Schematic view of the sequence pattern and the observing positions in the On-On observation

Most of the items for the On-On mode are as same as what described in the Single Point section. One important difference is that there is no choice for 'Beam Rotation Angle' (removed) and 'Calibration Mode'. Therefore, these values are fixed as 0 degree and LDM1-SKYM1. Note that off-position is automatically defined as 70" (the beam separation of the FOREST Beam 1 and 3) and rotates around the on-position depending on LST and EL, and is located both sides of the on-position). The reference table for the On-On observing mode is used to define where is used for the absolute intensity calibration: 'Reference ID' refers to the position described in the Refernce Table and that position will be used as a blank sky.

'Number of Sequences' for On-On mode is defined by usual on-source scan number of one beam. The total on-source scan number with two beams is the double number entered here. The users should enter the value taking into account that 'Number of Sequences' in the scan table is a half number of "Scan number for one ON-point" in the results of the observing time estimator.

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OTF

On-the-Fly mapping method is available for all receivers. Required parameters can be derived with Time Estimator for On-The-Fly Observations (also see A Guide to OTF Observations with 45-m).

nobs: Scan Tab: On-The-Fly mode


Notes for OTF scan

Scan Parameters

A window to specify a scan pattern. Some symbols used below are as same as in Time Estimator for OTF.
conceptual diagram for On-The-Fly mode
Schematic view of OTF parameters

Calibration

Parameters for absolute intensity calibration.

Notes for the observations with the FOREST receiver using four beams

Users must carefully make the scan table when observing with the FOREST receiver since the FOREST has the asymmetric beam alignment to the rotation centre of the dewar. An optical axis of the FOREST receiver is designed to be along the Beam 1. This changes the beam alignment due to a declination of a target. If users intend to observe an area of 2A [arcsec] x 2B [arcsec] with a position angle of 0 [degree] using OTF scan mode, the parameters for the scan table should be as follows:

Declination > (+35d56m40s.17)? Beam Rotation Angle [deg.]* start position X and Y Spacing (d), Number of Scan (Nrow)
Yes
0
(-A, -B)
d x (Nrow-1) = 2B + BS**
Yes
+90
(-A, -B-BS**)
d x (Nrow-1) = 2B + BS**
Yes
-90
(-A-BS**, -B)
d x (Nrow-1) = 2B + BS**
No
0
(-A-BS**, -B-BS**)
d x (Nrow-1) = 2B + BS**
No
+90
(-A-BS**, -B)
d x (Nrow-1) = 2B + BS**
No
-90
(-A, -B-BS**)
d x (Nrow-1) = 2B + BS**
*) The mechanical limit of a rotation angle of the FOREST should be within +-100 degrees during one observing script. Please set 'Beam Rotation Angle' to an appropriate value. Users can know 'appropriate value' by using 'multpa.py' command.
**) Each beam separation (BS) of the FOREST receiver is 50 arcsec.

The following figures illustrate a mapping area with the beam alignment of the FOREST based on a declination of a target(> or < the latitude of the observatory[+35d56m40s.17]) and the Beam Rotation Angle (0, +90, and -90 deg.). The area overlapped with four beams is shown as a filled blue box.

Case 1: Decl. > +35d56m40s.17, Beam Rotation Angle = 0 deg.
FOREST OTF pattern for Nothern sky with Beam Rotation Angle of 0 degree

Case 2: Decl. > +35d56m40s.17, Beam Rotation Angle = 90 deg.
FOREST OTF pattern for Nothern sky with Beam Rotation Angle of 90 degree

Case 3: Decl. > +35d56m40s.17, Beam Rotation Angle = -90 deg.
FOREST OTF pattern for Nothern sky with Beam Rotation Angle of -90 degree

Case 4: Decl. < +35d56m40s.17, Beam Rotation Angle = 0 deg.
FOREST OTF pattern for Southern sky with Beam Rotation Angle of 0 degree

Case 5: Decl. < +35d56m40s.17, Beam Rotation Angle = 90 deg.
FOREST OTF pattern for Southern sky with Beam Rotation Angle of 90 degree

Case 6: Decl. < +35d56m40s.17, Beam Rotation Angle = -90 deg.
FOREST OTF pattern for Southern sky with Beam Rotation Angle of -90 degree

After making observing scripts, please confirm that the observing region is as same as you intend to with ''obspoint.py''.

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Cross Point

This mode allows the user to create an observing script for a pointing observation (a 5-point cross-scan). Many of the items here are the same as the Single Point mode, and the user should consult the items described the Single Point mode. Some of the items listed in the 'Scan Parameters', however, are unique to the Cross Point mode.

nobs: Scan Tab: Cross Point

The best way to prepare a scan table for a pointing observation is to use a sample file, which can be accessed by pushing the "Sample" button. Naming rules of sample files for the pointing observation are as follows:

pt[frequency in GHz]_[integration time in seconds]([receiver]).nscan

The observatory prepared 22 GHz, 43 GHz and 86 GHz sample files which correspond H2O maser, SiO(J = 1-0) maser, and SiO(J = 2-1) maser, respectively. T70 and FOREST receiver can observe SiO(J = 2-1) maser at 86 GHz, although the absolute intensity calibration systems are different each other. When you use FOREST for pointing observation, please use one of sample files with a name of

pt86_~f.nscan.

If you find that the pointing source is too strong or weak to observe with default integration time, please modify the integration time in 'Scan Parameters' and 'Calibration' section.

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Multi Point

This scan mode should be selected when the user would like to observe multiple points during one observing script. The Single Point section may help you to make 'Multi Point' scan table.

nobs: Scan Tab: Multi Point

Scan Parameters

Calibration

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Beam Rotation Angle of FOREST

For a multi-beam receiver, positions of beams rotate on the celestial sphere along time. FOREST equips a rotator in order to avoid a rotation of beams. Since the rotator has a limitation on rotation angle (from -100 degrees to 100 degrees), users need to set a beam rotation angle. The following figures represent the beam alignment of the FOREST based on a declination of a target(> or < the latitude of the observatory[+35d56m40s.17]) and the Beam Rotation Angle (0, +90, and -90 deg.). Note that the Beam 1 is always centred on the map coordinate (XY coordinate) unless users explicitly shift start position (for OTF) or observing positions (for Multi Point mode). In order to check whether or when the rotator of FOREST reaches the limitation of the rotation angle with the initial rotation angle you specified, please use a python tool the observatory offers "multpa.py". The usage is explained here.

Case 1: Decl. > +35d56m40s.17, Beam Rotation Angle = 0 deg.
FOREST beam distribution in Nothern sky with Beam Rotation Angle of 0 degree

Case 2: Decl. > +35d56m40s.17, Beam Rotation Angle = 90 deg.
FOREST beam distribution in Nothern sky with Beam Rotation Angle of 90 degree

Case 3: Decl. > +35d56m40s.17, Beam Rotation Angle = -90 deg.
FOREST beam distribution in Nothern sky with Beam Rotation Angle of -90 degree

Case 4: Decl. < +35d56m40s.17, Beam Rotation Angle = 0 deg.
FOREST beam distribution in Southern sky with Beam Rotation Angle of 0 degree

Case 5: Decl. < +35d56m40s.17, Beam Rotation Angle = 90 deg.
FOREST beam distribution in Southern sky with Beam Rotation Angle of 90 degree

Case 6: Decl. < +35d56m40s.17, Beam Rotation Angle = -90 deg.
FOREST beam distribution in Southern sky with Beam Rotation Angle of -90 degree

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[General Instruction] | Introduction: 'nobs' | Project Tab |
[Line Observation] | Source Tab (Line) | Reference Tab (Line) | Scan Tab (Line) | Device Tab (Line) |
[Continuum Observation] | Source Tab (Cont.) | Reference Tab (Cont.) | Scan Tab (Cont.) | Device Tab (Cont.) |