[daip] SETJY
Eric Greisen
egreisen at nrao.edu
Fri Oct 18 11:25:02 EDT 2013
Andreas Brunthaler wrote:
> Dear Eric,
>
> I hope you are all back at work now in Socorro. I'm having some problems
> with the velocity calculation in SETJY. I compared the results I get
> when using the 31DEC2011 and the 31DEC2013 versions and get different
> results for the same input parameters.
>
> I'm using OPTYPE '' and the following information:
>
> SYSVEL 18
> RESTFREQ 6.668E+09 519200
> VELTYP 'LSR'
> VELDEF 'RADIO'
> APARM 501,0
>
> Now, If I use the 31DEC2011 version, I get in the SU table:
>
>
> COL. NO. 2 18 19
> ROW SOURCE LSRVEL RESTFREQ
> NUMBER M/SEC HZ
> 2 G000.31-0.20 1.978371D+05 6.668519D+09
>
>
> In the 31DEC2013 version, I get:
>
>
> COL. NO. 2 18 19
> ROW SOURCE LSRVEL RESTFREQ
> NUMBER M/SEC HZ
> 2 G000.31-0.20 179825.49691 6668519456.0
>
>
> If I use OPTYPE = 'VCAL' in the 31DEC2013 version, I get yet another value:
>
>
> COL. NO. 2 18 19
> ROW SOURCE LSRVEL RESTFREQ
> NUMBER M/SEC HZ
> 2 G000.31-0.20 233796.30089 6668519456.0
>
> Apart from the different values I also get a different format. Now, if I
> run CVEL on this, I get shifts of < 1 channel for the 31DEC2011 version
> (as expected). However, for the 31DEC2013 version, I get shifts of 50
> channels (using OPTYPE='') and 100 channels (using OPTYPE='VCAL'), which
> corresponds to the velocity offsets above.
>
> Any idea where this difference comes from?
>
> Andreas
>
This is bizarre - I thought we had tested everything when I did the VCAL
option for you and all was well. I suspect that I had better know more
about this data set - I suspect a TASAV output file would be sufficient
for testing.
Eric
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