From: <gcimo_at_email.protected>
Date: Thu, 12 May 2005 21:42:46 +1000 (EST)

Hi Tasso,

of course, it would be better if Tsys is stable.
However, if it varies by a *few* K, it should be still fine for the
experiment.

Anyways (I know that the changeover is during the night) the cabling
could be done during the setup/fringe checking, if it does not interfere
with the fringe test.

Regards,

Giuseppe

On Thu, 12 May 2005, Tasso Tzioumis wrote:

>Hi everyone,
>
>I'm at Mopra checking out the system in preparation for the VLBI. I've
>just checked the 1.6 GHz band that we used for VSOP and the interference
>from Iridium/Globalstar in the 64 MHz input band to the DAS is still quite
>strong.
>
>This does not affect the recorded band BUT it does affect the wideband
>Tsys measurements. Here at Mopra the Tsys can vary by a few K between
>10sec cycles that the system uses here.
>
>It is possible (with some rewiring) to measure the Tsys in a narrower band
>while recording via the 2nd frequency chain. This can be done easily at
>the ATCA and with some manual recabling at Mopra (and a change in the
>local schedule). We used to do this for VSOP.
>
>I guess it does not matter much for the VT tests to NZ. The only other
>experiment affected is V172C. I do not not know what the experience was
>with V172a and V172b. Does this need accurate Tsys? Note that the
>changeover is around 4am! But if you do need to calibrate the data
>accurately we should try it.
>
>Any comments from the PI? Giuseppe?
>
>Cheers
>Tasso
>
>----------------------------------------------------------------------
>Tasso Tzioumis, Australia Telescope National Facility, CSIRO |
>Location: Cnr Pembroke & Vimiera Rds, Marsfield, NSW, 2122, AUSTRALIA |
>Post: PO Box 76, Epping, NSW 1710, AUSTRALIA |
>Phone: +61 2 9372 4350 Fax: +61 2 9372 4450 or 4310 |
>Email: Tasso.Tzioumis_at_csiro.au |
>URL: http://www.atnf.csiro.au/~atzioumi/ |
>----------------------------------------------------------------------
>
Received on 2005-05-12 21:43:12