ATNF VLBI Wiki

Ftp: ftp://ftp.atnf.csiro.au/pub/people/vlbi/v255/v255d

The purpose of these observations is to obtain the second epoch for proper motion/parallax observations of the methanol maser sources NGC6334F and NGC6334I(N) (first epoch was v255c in Nov08). We are using the same observing mode as for previous v255 experiments (although the maser band frequency has shifted upwards by 2 MHz compared to the Nov 2008 session). We will observe both masers and phase calibrators with dual polarization 2×16 MHz bandpasses, but the correlator output will be high spectral resolution around the masers (NGC6334F should show a strong peak at a sky frequency of around 6669.56 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.

The experiment has 4 distinct sections, minor setup changes are required between 13:00:00 and 13:20:00 then at 14:35:20 and 00:03:30 UT

1. 13:00:00 - 13:20:00 UT : Observing 3c273 with the v255d.5cm setup (dual polarization 4 x 16 MHz bandpass setup).
2. 13:20:00 - 14:35:20 UT : Use the single polarization (LCP), 4 x 16 MHz bandpass setup. We are looking at ICRF sources over as wide a range of azimuths and elevations as possible for atmospheric delay calibration for the astrometry.
3. 14:35:20 - 00:03:30 UT : Use the dual polarization 2 x 16 MHz bandpass setup. This portion of the experiment is mainly switching every few minutes between the two maser sources NGC6334F and NGC6334I(N) and three phase calibrators. There is an ICRF run between 1906 and 2004 UT, this one is done with the maser setup (to reduce the number of changes overall).
4. 00:03:30 - 01:00:00 UT : Single polarization (LCP), 4 x 16 MHz bandpass setup for another 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.

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 810 MHz (IFP#2) for the 4 x 16 MHz setup and 810 MHz for the 2 x 16 MHz setup. For Ceduna, if you set the agilent to 11.1 GHz rather than 11.4 GHz, then you can use the same LOs as at Hobart.

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 before the experiment. Note “catie” should be setup for Rcp/Lcp (Lcp is selected in cdisko)

During the first 20 minutes 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 modes will need to be used to calibrate these.

Everyone records with a dual polarisation/6.7 GHz setup. ATNF records at 512 Mbps, ie Huygens/Channel 1-8 in cdisko with DAS1 and DAS2

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

Hobart and Ceduna retune IFP#1 to 6316 MHz. Parkes/Mopra/ATCA run with DAS#1 centered at 6316 and DAS#2 at 6658 MHz and record Chan 3,4,7,8 in cdisko. Parkes will have to lorun. ATCA and Mopra have the frequency change built into the schedule.

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