Dear Peggy,

Thanks a lot for your e-mail.
I already made a try by scalling the Tsys records from 43GHz to the
other two frequencies. As you suspected, the result was not very good,
because the problem was not in the Tsys records but in the data
flagging. I couldn't recover any additional data.

Therefore, it would have no sense to compute the Tsys in the way you
propose.

Thank you very much again.

Regards,

		Ivan Agudo



El mar, 20-09-2005 a las 22:34, Peggy Perley escribi:
> Dear Ivan,
> 
>     I have investigated the problem with the SC tsys' for BA071C.  The
> SC focus/rotation unit was having problems at the time and some scans
> were flagged by the system because the subreflector was not always in
> the correct position.  Now, the amount that the rotation/focus was
> off varied from scan to scan, sometimes it wasn't off by much and
> on other scans quite a bit.  Whenever a scan is flagged, there are no
> tsys records logged in the monitor data, hence, no tsys in your cal
> file.  Recovering the monitor data won't help in this case.  However,
> the total and switched powers are logged even if data are flagged, so
> you can calculate the missing tsys if this is useful from the equation
> 
> tsys = total power/switched power   *  tcal/2
> 
> The tcals are in the cal file and I can sent you a text file with
> the total and switched powers.  Let me know if you want to try this.
> I can't guarantee which flagged SC scans might have usable data.
> 
> Regards,
> Peggy Perley
> 
> Dear Data Analyst,
> 
> When starting to reduce one of my VLBA observations, BA071C (performed
> on April 2005) I realized that most of the 15 and 22 GHz Tsys records
> for SC are missing. These measurements are not present in the
> corresponding TY table, nor in the "ba071ccal.vlba" file. The plots on
> "ba071ctsm.SC.ps" don't show the missing Tsys measurements, just a few
> 15 and 22 records at the beginning and at the end of the observation.
> That is, of course, not enough for a correct amplitude calibration of
> the observation.
> 
> More strange is that neither the "ba071clog.vlba" nor the
> "BA071C.20050402.sniff" files contain any comment about this lack of
> measurements nor a related problem with SC during the observations.
> 
> Would it be possible to recover the missing Tsys records?
> 
> Thank you very much in advance for your help.
> 
> Best regards,
> 
>                  Ivan Agudo
-- 
--
Ivan Agudo             iagudo@mpifr-bonn.mpg.de
Max-Planck-Institut fuer Radioastronomie
Auf dem Huegel 69         Tel.: +49-228-525-217
D-53121 Bonn / Germany    Fax : +49-228-525-229
http://www.mpifr-bonn.mpg.de/staff/iagudo/