• View
• Go to new wiki
• History
• Print

V255A

V255a Setup:

The beginning and end of the experiment will use the following setup

Ftp: ftp://ftp.atnf.csiro.au/pub/people/vlbi/v255/v255a

Comments:

Background:

The purpose of these observations is to obtain a first epoch for proper motion/parallax observations of the methanol maser source G9.62+0.20. We are trialing a new observing mode where we will observe both masers and phase calibrators with 2x16 MHz bandpasses, but the correlator output will be high spectral resolution around the masers (G9.62+0.20 should show a strong peak at a sky frequency of around 6668.4 MHz during these observations) and standard continuum for the phase reference source. The idea is to have a mode which expands the number of suitable phase reference sources available for spectral line sources.

Specifics:

The experiment has 3 distinct sections, minor setup changes are required at 15:01:10 and 23:15:10 UT

1. 0900 - 15:01:10 UT : Use the single polarization (LCP), 4 x 16 MHz bandpass setup. Up until 1415 UT we are using the time to search for potential phase reference sources for future maser proper motion/parallax observations and from 1415 - 1510 UT we are looking at ICRF sources over as wide a range of azimuths and elevations as possible for atmospheric delay calibration for the astrometry.
2. 15:01:10 - 23:15:10 UT : Use the dual polarization 2 x 16 MHz bandpass setup. This portion of the experiment is mainly switching every few minutes between the maser G9.62 and two phase calibrators. There is a 45 minute ICRF run between 1930 and 2015 UT, this one is done with the maser setup (to reduce the number of changes overall). From 2015 - 2115 UT we have added in a second maser source G8.68 (although a strong maser it is much weaker than G9.62) to test the feasibility of observing two maser targets in a single session for future observations.
3. 23:15:10 - 0000 UT : Back to the single polarization (LCP), 4 x 16 MHz bandpass setup for a final ICRF run.

During the ICRF runs we have sometimes had to exclude certain antennas (particularly Parkes) from observations of some sources in order to get a good spread of azimuths and elevations.

Observing comments for each antenna:

Parkes, ATCA, Mopra :

Cable up with the Huygens cable for the entire experiment. Observe with dual DAS setup using 2 DASes for the 4 x 16 MHz setups and 1 for the dual polarization 2 x 16 MHz setup. Record using the following cdisko channel selections at the appropriate time ranges. Stop the recorder in between! At Parkes you will have to change the frequency manually running for example (in a pavo xterm) > lorun @2008_METH-split.cmd

ATCA will have to cacal at 6.3/6.7 GHz and 6.7/6.7 GHz.

Hobart, Ceduna :

The 4 x 16 MHz bandpass setup will require feeding two separate LOs into IFP#1 and #2 on the DAS/frequency translator and splitting the LCP signal so that is feed into both sides. For Hobart the LOs should be set to 468 MHz (IFP#1) and 809 MHz (IFP#2) for the 4 x 16 MHz setup and 809 MHz for the 2 x 16 MHz setup. For Ceduna, try setting the agilent to 11.1 GHz rather than 11.4 GHz, then you can use the same LOs as at Hobart.

Hart :

Scheduled from 2150 - 2325 UT. The last source is after the change to the single polarization 4 x 16 MHz bandpass setup. Although all the other antennas should change, Hart should observe with the dual polarization 2 x 16 MHz bandpass setup.

DAS calibration

During the fringe check we will need to calibrate the delay between the two ATNF DAS, and the delay between Hobart/Ceduna in dual pol and single pol mode. The following set of tests are suggested. Once fringes are found we will want at least 5min of data in each mode which is saved.

ATNF DAS offsets:

Everyone records with a dual polarisation/6.7 GHz setup. ATNF records at 512 Mbps (ie Huygens/Channel 1-8 in cdisko).

Hobart/Ceduna Single pol calibration

Hobart and Ceduna cable up with LCP into both IFP, but remain at 6.7 GHz. Pks/ATCA/Mop record chans 1-4.

Split freq fringe test

Hobart and Ceduna retune IFP#1 to 6316 MHz. Pks/Mop/ATCA run with DAS#1 centred at 6316 and DAS#2 at 6657 MHz and record Chan 3,4,7,8 in cdisko.

Observing Logs

Parkes onsource flagging
ATCA onsource flagging
Mopra onsource flagging
Mopra Tsys (plot)