The receiver should be tuned to the frequency you observe. In general, you need to tune the receiver once at the beginning of your observations (If you observe different frequency set-up with the same receiver on the same day, you tune the receiver at every changing the frequency set-up). Since tuning methods differ one by one, this page shows how to tune each receiver. Before moving to the following procedures, you should change the direction of mirrors in order to the receiver you use can receive the signal from the sky. If you will observe continuum, special set-up is needed. Please print your device tables and pass it to the assistant.
==斜体のcontinuumのところは不要だと思う↑==
==続くT70の部分は新旧HP間の引き継ぎを省略した、一方でeQ, TZ, 7BEEなどは加筆の必要があるかも？==
H22, H40, Z45 receivers
It is no need to tune H22, H40, and Z45 receivers. After changing the direction of mirrors, you can start an observation by choosing the observing script at COSMOS GUI and pressing “START OBSERVATION” button.
Go to “A Flowchart for the Remote Observations with the Nobeyama 45-m Telescope”
FOREST
Monitors for the FOREST receiver are placed in the NRO_RemoteObs_4 viewer. To tune the FOREST receiver and to monitor the status, three windows are used: “FOREST 1 (1) – Remote Viewer”, “FOREST Monitor”, “FOREST Live Camera”.
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Figure 1: Image of the NRO_RemoteObs_4 viewer. In order to tune the FOREST receiver and to monitor the status, three windows that are boxed and markded as 1 (in red), 2 (in blue), and 3 (in yellow) are used (details are described below).
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Figure 2: “FOREST 1 (1) – Remote Viewer” (marked 1 in Figure 1) is the main window to tune the receiver.
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Figure 3: “FOREST Monitor” (marked 2 in Figure 1) has been showing the current status of the FOREST such as dewar temperature, the LO frequency, the rotation angle of the receiver, etc..
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Figure 4: “FOREST Live Camera” (marked 3 in Figure 1) projects the movie of the FOREST receiver viewed from above.
The FOREST receiver can be tuned with the terminal shown in “FOREST 1 (1) – Remote Viewer”. Since a tuning procedure for the FOREST is followed by the steps described below, it is convenient for you to use the command-line history (pressing the up and down keys at the terminal).
- Initialise the FOREST
Enter the following command to initialise the FOREST receiver.> forest_initialize.py - Receiver tuning
You can tune the FOREST applying the best parameters which the observatory previously measured. The tuning command is as follows:> forest_SIS_tune.py tuning/loXXG-UL_step3_yyyymmdda.cnf
where XX is the LO frequency, UL is a sideband which you intend to observe (Upper Sideband[USB], Lower Sideband[LSB] or USB/LSB), and yyyymmdda is the date when the observatory measured the parameters. Please select LO frequency as the frequency nearest to you specified in the device table. (The observatory send the PI a filename which suits for your observations. Please use it unless there is any problem.)
For example, in the 2020-2021 observing season, the observatory prepares following tuning parameter sets (The names of parameter file may be changed during the observing season).
==ここに表== - Measurements of the system noise temperature and the sideband separation ratio
To check the performance of the FOREST, you should measure the system noise temperature (Tsys) and the sideband separation ratio (or Image Rejection Ratio: IRR) along with different IF frequency. First of all, push the “Tuning” button on the antenna console to set EL = 70 deg. Measurements will be performed with the following commands:> exp_irr_with_IF_freq_sweep.py --lo_freq 105 --start 4 --stop 12 --step 1
where “lo_freq” is the 1st LO frequency [GHz], which you specified in the frequency seting file (DeviceSetting_***_xlsx) that you submitted with your proposal, “start” and “stop” are the IF frequency [GHz] where the measurements start and end, respectively. Regarding the “lo_freq”, the first decimal place may be enough because of the flatness of receiver performance. “step” is the frequency interval [GHz] of Tsys and IRR measurements between “start” and “stop”. In the example above, the measurements are under the setup of the LO frequency of 105 GHz, IF range of 4-12 GHz with a step of 1 GHz. These values should vary the observing frequency and numbers of target lines. The required time differs the data number to measure: typically saying it takes a minute to obtain the data for the setup of IF = 4-12 GHz with 1 GHz step.
When the measurements end, the results will be shown on the terminal with values and the FOREST Monitor (bottom right area) with plots. If you click the plots on the FOREST status monitor, you can see the zoomed-up one (see the figure below). You can obtain the data by clicking a string under the plot (results_***_irr_if_sweep.zip).
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Figure 4: Results are plotted on the bottom-left corner of “FOREST Monitor”
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Figure 5: An example of Tsys and IRR measurements. Tsys in blue (the left axis) and IRR in black (the right axis).
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Figure 6: The relations between the beams, the polarisations, and the sidebands in Figure 5 - Start observations
The FOREST is now ready for observations. For a safety observation, we recommend you to run the following command to fix the tuning parameters unless you explicitly unlock.> forest_start_observation.py - End observations
When your observation ends, please run the following command to make the FOREST tuning machine a standby state.> forest_end_observation.py
In the end, set the FOREST itself a standby state.> forest_finalize.py
How to address the trouble that the terminal does not respond ordinary during tuning of FOREST receiver
Due to troubles (including misoperations), the terminal may not respond, or the tuning process may suddenly stop. In principle, we hope that you report the situation to the assistant and ask for help. But you may resolve a problem with the following process (please report the situation even if you could solve the problem by yourself).
- (In case that the terminal does not respond and the Tuning Machine seems not to execute a command)
- Press Cntl key and C key at the same time to force-quit the command. Enter the following command to set flags as a normal end:
> rforest_end_operation.py - If you faced the problem before starting observations, the observatory recommends to tune the FOREST receiver again (i.e., start from the initialisation).
Go to “A Flowchart for the Remote Observations with the Nobeyama 45-m Telescope”