Swedish-ESO Submillimetre Telescope – SEST

Spectral Line System Resolution Test

By F.Mac-Auliffe

September 18^th 2001

1. Log on as Director on Vela

2. Set the velocity to 0 km/s in the topocentric system (Dopcor window)

3. Connect the receiver / AOS combination (Connect window) as well as the line (Line window) to observe according to the following table:

Receiver	Connect	Line	Trec
RX100	HRS + LR2	SiO (2-1, v=1)	100 K
RX150	HRS + LR1	CS (3-2)	140 K
RX115	HRS + LR2	SiO (2-1, v=1)	70 K
RX230	HRS + LR1	CO (2-1)	145 K

4. Tune (Tune window) and measure Trec (Rectemp window).
For receiver temperature reference values look at the table above.

5. Set the observing mode to Position Switching (Obsmode window)

6. Inject the test signal.
In the tune screen, go to the Test signal menu and click on Test Signal Enable. Then select the Signal band. Look at the spectrum analyzer and you should see a strong and, usually saturated test signal. In order to get a non-saturated signal; connect the HP-attenuator 8494B/8495B to the output of the AOS’s in the IF-Distribution rack, according to fig#1.

7. Take reference spectra using the AOS window. Set the integration times to 5/5/5 seconds (spe/ref/cal) and check that the test signal is not saturated. When ready, take a signal spectra and finally another reference spectra.

Data Reduction and Analysis

- Convert the FITS files into Class format by using the FITS2CLASS routine.

Click on the CLASS button in the PSM to start a Class session. Then, execute the command:

LAS> @SEST:FITS2CLASS [Output file] [First scan] [Last Scan]

and follow the program instructions to save the fits files into a Class file.

- The next step is to reduce the data. There are two ways to reduce the data:

- Execute from CLASS the following command:

LAS> @SEST:PURITY [Scan number]

and follow the program instructions (recommended)

- Reduce the data manually by executing the following set of CLASS commands:

LAS> DEV XAUTO                                     à Open graphical device
LAS> SET UNIT C                                       à Set unit to channels
LAS> FILE IN [INPUT FILE]                      à Open Input file
LAS> FIND/ALL                                          à Retrieves all the spectra

LAS> GET [SCAN]                                      à Load a spectra into memory
LAS> SET MODE X 980 1020    à for HRS Spectra
           SET MODE X 700 740                      à for LRS Spectra
LAS> PLOT                                                  à Plot the spectra
LAS> SET WINDOW                 à Set the emission zone for the later baseline subtract

Mark with mouse for start and stop channels (on both sides

of the line peak) and press <space>. Finish by pressing <e>
LAS> BASE 1/PL à Fit a 1^st order baseline and plot the fit

LAS> PLOT                                                  à Plot the spectra
LAS> GAUSS                                               à Fit a Gaussian curve and calculate the line parameters
LAS> FIT                                                      à Plot the fit over the spectra plot
LAS> HARDCOPY/PLOT                          à Produce an hardcopy of the final spectra

- Store the plots in the binder “Spectral line system resolution test” and fill in the table (included in the binder).

- Important: Do not delete the Class File containing the spectra. Please, leave the file on Vela or Puppis and let me know where the data is saved for further analysis and archive.

Current reference values

Receiver / AOS	Width	Center
RX100 – HRS	3.0	1000
RX100 – LR2	1.5	720
RX150 – HRS	8.0	1000
RX150 – LR1	2.0	720

Figure 1