iraf.net

Hello!

I'm doing IR photometry with IRAF. To summarize, I have my science images (dark subtracted and bias corrected) and sky-only images which I need to subtract from my science images. The problem is: When I run imarith to subtract the sky images from my science images, the resulting image acquired extensions.

My unsubtracted images are named (band)_raw.(number).fits, the sky images are sky_(band)_(number).fits and the final science images are (band).(number).fits.

ecl\$this->_split2($m[0]) display Ks_raw.0050.fits --\$this->_split2($m[0]) works, displays image correctly in ds9/ximtool
ecl\$this->_split2($m[0]) display sky_Ks_0050.fits --\$this->_split2($m[0]) works, displays image correctly in ds9/ximtool
ecl\$this->_split2($m[0]) display Ks.0050.fits --\$this->_split2($m[0]) ERROR: FXF: must specify which FITS extension (Ks.0050.fits)

However

ecl\$this->_split2($m[0]) display Ks.0050.fits[0] --\$this->_split2($m[0]) works
ecl\$this->_split2($m[0]) display Ks.0050.fits[1] --\$this->_split2($m[0]) works
ecl\$this->_split2($m[0]) display Ks.0050.fits[2] --\$this->_split2($m[0]) works
ecl\$this->_split2($m[0]) display Ks.0050.fits[3] --\$this->_split2($m[0]) works

However, some images have more extensions than others. Two (correlated) questions arise then:

1) Why this is happening? I checked the task parameters and I didn't found any option related to this;
2) How can I run imarith and produce a single image as output (I mean, without a number of extensions)?

I need to have these final images as single extension .fits to run then a dithering photometry script.

Any help appreciated!!

There's nothing in IMARITH to produce extensions automatically so I have no idea how this happened. I assume you ran the command as:



or was it something else? Was this done from some other script? If so, does running the command manually do anything different? What version of IRAF? Could you upload the raw and sky image to the anonftp at ftp://iraf.noao.edu/pub?

Sorry for the delay in the answer. I put the imarith commands in a text file and ran

ecl\$this->_split2($m[0]) cl

Sorry, I don't know what happened with my answer, but it didn't came complete.

I put the imarith commands in a text file and ran



I guess this is a problem with version 2.16.1, because I just ran these scripts in a 2.14.1 installation and the resulting images came with no extensions, as they should.

By the way, thanks for your attention! Can I mark the thread as closed?

Two thoughts:

The first is to try the command

cl\$this->_split2($m[0]) reset use_new_imt = no

before running your script. This disables the new image template code, which, hasn't specifically been linked to this problem but since it relates to extensions might be an issue.

The second is that when you run a script with indirection like that, any prompts are answered by the next line in the script file which might somehow be causing the wrong line to be executed or the arguments to get confused. A lot depends on what is actually in the 'script.cl' file.

About your second thought, I didn't thought about it... And I think my script isn't even a proper script, since it is something like this:



repeated to subtract every sky image from each raw image.

As for your first suggestion, I'll try it, ok? Did the imt changed? Where can I find a changelog?

Changing the 'use_new_imt' on the command-line just changes the value for the CL session you are in, you can make the change permanent by setting the value in your login.cl (or the system hlib$zzsetenv.def file).

The imt changes are documented in

https://iraf.net/article.php?story=20110524165039468

as well as the release notes in ftp://iraf.noao.edu/iraf/v216/v216revs.txt

As for your suggestion



it worked perfectly! The images came with no extensions! Yesterday I ran my script in other computer, with an IRAF 2.14 installation, to produce the images. After resetting the imt to the old one, and saving the resultant image as a test, I compared both (counts, imstat and other comparisons) and they're absolutely identical.

Thanks for the help!!!