Testing ccdproc

To test your version of ccdproc, you need to download the test FITS files (2.4Mb gzipped tar file):
ccdtest.tgz
and install it. It will unpack into the CCDTest/ subdirectory. The usual practice is to install thus under the CCDProc/ source directory.

In this test suite, you will find the following files: 

    README.test  --> test instructions
    test.pro     --> the proc file for the test suite.
    mzero.fits   --> a mean zero frame
    dark100.fits --> [an unconvincing synthetic] mean 100s dark frame 
    mvflat.fits  --> a reduced, normalized V-band flat-field frame
    b14.fits     --> a raw V-band image
    test.fits    --> the reduced V-band image, to compare with your output.
The test data are 512x512 CCD data provided by the University of Tasmania group.

The readout of this CCD uses with 16 pre-read columns and 20 post-read columns (pre- and over-scan in some parlance). The active area of the CCD is 512 pixels between columns 17 and 528, and 512 pixels between rows 1 and 512. The mean zero and V-band flat-field frames have had the pre-/post-scan columns trimmed, so we must similarly trim the raw CCD image. For this test, we will ignore the pre- and post-scan columns, and do the following reductions:

  1. Trim the raw data to 512x512
  2. Subtract the mean zero frame
  3. Subtract a 100s mean dark frame scaled by a factor of 3.0 to the raw image exposure time of 300s.
  4. Divide by the normalized V-band flat field
  5. Compute the mean stellar FWHM, modal SKY, and photometric thresholds TSMIN and TSMAX to be used as starting points for DoPhot reduction. The estimations will use a CCD gain of 2.7 e-/ADU.
The output FITS data will be short integers (bitpix=16), and we will generate a log file named "test.log" to keep track of what we did.

The test.pro file thus looks like this (exclusive of comments): 

    DTYPE LONG             <-- output format is long integers (bitpix=32)
    LOGFILE test.log       <-- make a logfile named test.log
    TRIM [17:528,1:512]    <-- 512x512 active area of the CCD
    ZERO mzero.fits        <-- subtract the zero frame mzero.fits
    DARK dark100.fits 3.0  <-- scale dark100.fits by 3.0 and subtract it.
    FLAT mvflat.fits       <-- divide by the flat field frame mvflat.fits
    FWHMSKY GAIN=2.7       <-- estimate DoPhot input parameters using a 
                               CCD gain of 2.7 e-/ADU.
To do the test, type 
    % ../ccdproc -Ptest.pro b14.fits b14.red.fits
The files b14.red.fits, containing the reduced image, and test.log, containing the log will be created if successful.

Compare your results with the file test.fits using IRAF or whatever. Do not use the Unix "diff" utility, as the timetags on the HISTORY cards generated by ccdproc in the FITS headers will differ.

In addition, the output logfile (test.log) should look something like this: 

   1999-08-08T12:10:48: Processing b14.fits using procfile test.pro
   1999-08-08T12:10:48: Output filename: b14.red.fits
   (ccdproc:1999-08-08T12:10:49) Trimmed to [17:528,1:512]
   (ccdproc:1999-08-08T12:10:49) Zero: mzero.fits
   (ccdproc:1999-08-08T12:10:49) Dark: dark100.fits scale=3.00
   (ccdproc:1999-08-08T12:10:49) Flat: mvflat.fits
   (ccdproc:1999-08-08T12:10:50) FHWMSKY with GAIN=2.00
The last five lines will also appear as HISTORY cards in the output FITS header, along with the results of the FWHMSKY calculation, as this excerpt from the header shows: 
    SKY     =     2.9830000000E+03 / Modal SKY level (ADU)
    FWHM    =     8.0922317505E+00 / Mean stellar FWHM (pix)
    TSMIN   =     1.9309971619E+02 / DoPhot min threshold (THRESHMIN)
    TSMAX   =     3.6637601562E+04 / DoPhot max threshold (THRESHMAX)
    HISTORY   (ccdproc:1999-08-08T12:10:49) Trimmed to [17:528,1:512]
    HISTORY   (ccdproc:1999-08-08T12:10:49) Zero: mzero.fits
    HISTORY   (ccdproc:1999-08-08T12:10:49) Dark: dark100.fits scale=3.00
    HISTORY   (ccdproc:1999-08-08T12:10:49) Flat: mvflat.fits
    HISTORY   (ccdproc:1999-08-08T12:10:50) FHWMSKY with GAIN=2.00
Your mileage, of course, may vary.

Caveat

While this test uses mostly real data, its purpose is to verify that most ccdproc compiled correctly on your machine. The test is not meant as an illustration of all features of ccdproc, nor are the processing steps involved necessarily those that should be used in general.

Return to: [ ccdproc Homepage | OSU/PLANET Software Homepage ]
Updated: 1999 August 8 [rwp]