I dont understand this Immerge Error

[Arpad]

Hi,

I am trying to merge ATCA Data und Parkes Data at fits level. I have 2 Fits files, one from ATCA, one from Parkes. I tried to merge them using Immerge. I think I did everything to ensure they both fit together, but Immerge keeps saying:

### Fatal Error: Frequency could not be determined, in pbInit

What frequency is it talking about? I checked the fits files, both have the crval3 and restfreq keywords in them, so when importing in miriad, it should be imported accordingly. Also, when I use prthd to look at the header of the images, both show the frequency and restfrequency.

Any ideas?

Thx.
Arpad

[ste616]

Hi Arpad,

When submitting a report describing a problem like this, it is very helpful for us if you can include a pointer to your data and exactly what you have done to generate the problem. That way we can replicate the situation and start debugging. Thanks!

[Arpad]

Hi,

I thought I wrote all necessary things. Okay, from the beginning.

I got raw ATCA data, a mosaic of 18 pointings. I used miriad and (sorry for that) casa (because I got used to it) to calibrate and image the mosaic. I then converted the casa image to a fits file.
Then I got Parkes data at the same frequency, 6 cm, of the same field. I got it in an already calibrated form, and I must say I do not know how it was calibrated or who did it. I used an IDL script to create a map out of this data. This script created a fits file.

Then I loaded both fits files into miriad, used REGRID to project both fits files to the same projection type, and then I used IMMERGE. The inputfiles were the miriad images, first beeing the ATCA image, second one the parkes image. I put 25,40,meters into uvrange and left the flux factor empty. And thats when I got the above mentioned error. It seems to come from the ATCA image. I dug a bit around in the miriad code. Altough I dont understand much of fortran (Im more a python fan ), It seems to me that this pbInit subroutine is, in this case, searching for a frequency entry in the file. Or something like that....

Best Regards,
Arpad

[Mark.Wieringa]

Hi Arpad,

Immerge is trying to figure out the size of the beam of both images. If you add the beam parameters to each image you might get a bit further along.
It is looking for the following:
call rdhdr(lIn,'bmaj',bmaj,0.0)
call rdhdr(lIn,'bmin',bmin,0.0)
call rdhdr(lIn,'bpa',bpa,0.0)
but gets all zeros, the next thing it tries is to work out the beam from the telescope and the frequency, which also fails.

So if you can supply the beam parameters in the image headers (using puthd in=image/bmaj value=12.34 etc), it should be happy.

Cheers,

Mark