Dealing with LBC data using IRAF and ds9 (for Dummies)

You must have a current version of ds9 and IRAF. At the moment, at least at Steward, not everybody has an up-to-date version, and you can get wacky errors, e.g. trying to run ccdproc under mscred to subtract overscan works fine on some computers and dies with an obscure error about image size on other computers. The best bet is to find a friend with up-to-date ds9 and IRAF and use their computer.

1. Where's the data

As of Jan 17, data are now dumped to /Repository

2. How do I figure out what's in the files

hselect lbcb.*fits[1] $I,objname,obsra,obsdec,exptime,airmass yes

results in

lbcb.20070112.070915.fits[1]    dark    120.235
 lbcb.20070112.073449.fits[1]    NGC2366 07:28:54.8      +69:12:56.9     60.235  1.24422
 lbcb.20070112.073636.fits[1]    NGC2366 07:29:00.5      +69:13:22.6     60.235  1.24453
 lbcb.20070112.073821.fits[1]    NGC2366 07:28:56.7      +69:13:35.6     60.234  1.24480
 lbcb.20070112.074007.fits[1]    NGC2366 07:28:52.1      +69:13:34.3     60.235  1.24504
 lbcb.20070112.074308.fits[1]    NGC2366 07:28:54.7      +69:12:57.0     36.234  1.24533
 lbcb.20070112.222320.fits[1]    dark    18:37:29.5      +20:41:49.8     0.129   1.65619
 lbcb.20070112.222354.fits[1]    dark    18:37:29.9      +20:41:51.8     0.129   1.66095

3. How do I display a file on ds9?

Open a ds9 window, click on "FILE" then "OPEN OTHER" then "OPEN MOSAIC IMAGE'. This means you have an old version of ds9 and unfortunately you'll get something that looks like this:


This shows the 4 LBC ccd's (in order #3,2,1,4) in a line, which is not how it looks in the focal plane. Go find another computer. Simply downloading a new version of ds9 may not be all that you need: linux version must be up-to-date as well.

If, on the other hand, you click on "FILE" "OPEN OTHER" and get "OPEN MOSAIC WCS" you'll get somthing that looks like this:


You're all set.

The wcs that comes with raw data only contains the linear terms, and the zero point is from the TCS. So you'll need to apply the very significant higher order terms to do astrometry, but this will get you started.

4. How do I check the bias?

Load the mscred (mosaic reduction) package:


and run mscstat:

ms> mscstat  lbcb.20070113.233559.fits                                        
#               IMAGE     MIDPT    STDDEV
 lbcb.20070113.233559.fits[LBCCHIP1]     852.4     7.835
 lbcb.20070113.233559.fits[LBCCHIP2]     867.2      7.11
 lbcb.20070113.233559.fits[LBCCHIP3]     708.5     8.631
 lbcb.20070113.233559.fits[LBCCHIP4]     783.1     6.551

where in this case, the mscstat parameter file had the following:

ms> lpar mscstat
       images = "lbcb.20070113.233559.fits" Images
     (extname = "")             Extension name selection\n
       (gmode = no)             Global mode statistics?
      (fields = "image,midpt,stddev") Fields to be printed
       (lower = 500.)           Lower cutoff for pixel values
       (upper = 1000.)          Upper cutoff for pixel values
    (binwidth = 0.1)            Bin width of histogram in sigma
      (format = yes)            Format output and print column labels?\n
         (fd1 = "")             
         (fd2 = "")             
        (mode = "ql")           

"midpt" is the median 

-- Main.jill - 13 Jan 2007
Topic revision: r6 - 20 Jan 2007, pogge
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