[daip] Re: APCAL

[Thomas Krichbaum]

Hi Amy,

This is 86 GHz, LCP only. Tsys measurements are reliable and done similar as at the VLBA.
The 151 is not the tau, but is T_rx. So this is ok. The tau which I get with version 'new' is tau0=0.19,
which is also ok. Version 'new' complains about the T_rx=151K, which is not reasonable. 
The weatherfile does not pose a problem, as this runs well in AIPS version 'new'.

Obviously the problem is that this is not bad data, but a problem in the new source code.
For me it is important that future releases have this problem fixed. We use APCAL with 
in OPAC=mode really a lot.

To help debugging, I've wrote the data with FITAB on disk. Please look at:

ftp://ftp.mpifr-bonn.mpg.de/outgoing/p459kri/aips/

the data are in : SGRA-APR05.UVSRT
the cal-files are: 3MMAPR05.CAL and 3MMAPR05.WX

I also placed the AIPS cal and weather file there, so that you can rerun APCAL.
TY1, GC1 contain the calibration data obtained with ANTAB from 3MMAPR05.CAL

In SGRA-APR05.UVSRT
CL4 contains the fringe fitted solution;
SN4 the output from APCAL;
CL5 was made from SN4, CL4 using '2pt' and refa 3. Thus CL5 contains the final calibration,
as made with aips version 'new'.

If you want to rerun APCAL, please use dofit=1 for antenna 1 (=EB) and dofit=-1 for all other.
The data file SGRA-APR05.UVSRT contains 3 sources but for SgrA* it contains only data on 
one baseline (EFELSBERG-PICO VELETA). 

regards, Thomas

PS: I will be away from now until next Monday.


On Tuesday 23 May 2006 17:42, Amy Mioduszewski wrote:
> Hi Thomas,
> 
> You have run across a change I made recently.  We had complaints about 
> APCAL making bad fits, which is usually due to bad data.  What freq are 
> you observing at?  A Tau0 of 151 is really high.  Maybe this is 
> something peculiar about Effelsburg, or the lack of WX entries for 
> Effelsburg.
> 
> Eric thinks I should change it so it does not croak, but I fear for 
> novice users.  I think I will do a compromise that is the Tau0 or Trec 
> are less than 0 (obviously rediculous), I will still have APCAL die, but 
> I will just give warnings for high numbers.
> 
> Cheers,
> 
> Amy
> 
> 

-- 
Thomas P. Krichbaum                       
Max-Planck-Institut für Radioastronomie 
Auf dem Hügel 69                        
D-53121 Bonn / Germany

Tel. :  (Germany +49)-228-525-295
Fax :  (Germany +49)-228-525-229
e-mail: tkrichbaum at mpifr-bonn.mpg.de
URL:   http://www.mpifr-bonn.mpg.de/staff/tkrichbaum