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Dear iraf stuff: I'm student of National Astromomical Obervatory of China.
Could I ask you some questions about "focas standard test image results"? I set up the IRAF external package focas.
The example of FOCAS User's Guide can be followed.
I attached the info of the example (galfield.info).
So the focas can work. But when I try to follow the example of FOCAS standard test Image results.
I can't obtain same result with that of document.
My steps are:
copy ngc0002.fits to antoher place.
>rfits ngc0002.fits
.........
> Enter disposition (skip | quit | read | compare)? read
>Filename:ngc0002
>Review image file header? n
Then run the commands in ngc0002.run one by one.
But the final obtained objects are 0.
I attached the info file of the catalogue (ngc0002.info).
There are something different with table 11 of the document.

Field size: 272 508
> [ 271 507 in the document]
Field scan origin: 50 0
> [50 0 in the document]
Field corners in reference coordinates:
(50, 0) (321, 0) (50, 507) (321, 507)
>[(69, 1.00002)(339,1.0005)(69,50(339,507) in the document]sky: pts = 0 avg = nan sigma = 9
> [sky: pts= 200 avg =-0.087478 sigma =1.42302 in the document]
threshold above = 22.5 threshold below = 900
> [threshold above = 22.5 threshold below = 900 in the document]Could you give me some suggestions to solve the problem?
Bye the way what are pts, avg,sigma, threshold above describe for?Thank you very much!
Best Wishes
Xu Yan

Hello,From the information you sent FOCAS failed to find an initial guess for the sky, which it does from the first few lines of the image, and so it then failed further to find objects. pts is the number of initial sky pixels, avg is the initial sky average value, and sigma is the initial sky sigma.It has been many, many years since I've done much with FOCAS and I've never actually heard of someone trying to reproduce the work in the test results. You should continue to try on your own and maybe just accept that the galfield example is enough for you to learn from before trying to apply this to your project.As a hint, problems with determining the initial sky value are related to the optional arguments to the detect command. In your command you are saying that the pixels that can be used for sky must have values in the range of 129 to 137. For some reason this is not actually the case. You should example the pixel values in the first few lines either using FOCAS or IRAF tools. Displaying the image is always a good thing to do.Yours,
Frank Valdes