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Hello all,I'm hoping that is the result of a simple mistake I'm making, but I've been running ccdproc on a batch of images I acquired. I created the flat and bias images using standard protocol, and they look normal. However, when I actually run ccdproc on the object images, the object (in this case, Saturn and its moons) are either much, much dimmer, or have vanished in entirely in the reduced images. I've run ccdproc on similar images before using the exact same settings, and never had this problem before. What might be causing it?epar for ccdproc is set currently as:
images = @c_input List of CCD images to correct
(output = @c_output) List of output CCD images
(ccdtype= ) CCD image type to correct
(max_cac= 0) Maximum image caching memory (in Mbytes)
(noproc = no) List processing steps only?
(fixpix = no) Fix bad CCD lines and columns?
(oversca= no) Apply overscan strip correction?
(trim = no) Trim the image?
(zerocor= yes) Apply zero level correction?
(darkcor= no) Apply dark count correction?
(flatcor= yes) Apply flat field correction?
(illumco= no) Apply illumination correction?
(fringec= no) Apply fringe correction?
(readcor= no) Convert zero level image to readout correction?
(scancor= no) Convert flat field image to scan correction?
(readaxi= line) Read out axis (column|line)
(fixfile= ) File describing the bad lines and columns
(biassec= ) Overscan strip image section
(trimsec= ) Trim data section
(zero = c_bias.fits) Zero level calibration image
(dark = ) Dark count calibration image
(flat = c_flat.fits) Flat field images
(illum = ) Illumination correction images
(fringe = ) Fringe correction images
(minrepl= 1.) Minimum flat field value
(scantyp= shortscan) Scan type (shortscan|longscan)
(nscan = 1) Number of short scan lines
(interac= no) Fit overscan interactively?
(functio= legendre) Fitting function
(order = 1) Number of polynomial terms or spline pieces
(sample = *) Sample points to fit
(naverag= 1) Number of sample points to combine
(niterat= 1) Number of rejection iterations
(low_rej= 3.) Low sigma rejection factor
(high_re= 3.) High sigma rejection factor
(grow = 0.) Rejection growing radius
(mode = ql)A sample header from the images looks like this:jan1200037c_reduced.fits[2100,2100][real]: Mimas, Rhea (0 deg)
No bad pixels, min=0., max=0. (old)
Line storage mode, physdim [2100,2100], length of user area 5589 s.u.
Created Tue 19:52:34 13-Jul-2010, Last modified Tue 19:52:31 13-Jul-2010
Pixel file "jan1200037c_reduced.fits" [ok]
EXTEND = F / File may contain extensions
ORIGIN = 'NOAO-IRAF FITS Image Kernel July 2003' / FITS file originator
DATE = '2010-07-13T23:52:34' / Date FITS file was generated
IRAF-TLM= '2010-07-13T23:52:31' / Time of last modification
CTYPE1 = 'RA---TAN' /
CRPIX1 = 1487. /
CRVAL1 = 115.86 /
CDELT1 = 9.44444e-05 /
CTYPE2 = 'DEC--TAN' /
CRPIX2 = 1421. /
CRVAL2 = 21.2885 /
CDELT2 = -9.44444e-05 /
BLANK = -32768 / value used for NULL pixels
INSTRUME= 'BUSCA' / instrument used
TELESCOP= '2.2m Cassegrain' / telescope
OBJECT = 'Mimas, Rhea (0 deg)' / target description
RA = 27806.4 / target right ascension '07:43:26.4'
DEC = 76638.5 / target declination '21:17:18.5'
HA = 72910.9 / telescope hour angle '20:15:10.8'
EQUINOX = 2000.0 / equinox for ra and dec
AZIMUT = 271.889 / target azimut in degrees
ELEVATIO= 39.2555 / target elevation in degrees
AIRMASS = 1.58149 / target airmass at start of exposure
AIRMASS2= 1.58033 / target airmass at end of exposure
ST = 14317.3 / siderial time '03:58:37.2'
TEL-UT = 74343.8 / TEL-UT at start of exposure '20:39:03.8'
FOCUS = 25.0399 / telescope focus
OBSERVER= 'Aguirre, Guijarro' / name of observer(s)
SITE = 'Calar Alto, Spain' / name of the observing site
FILENAME= 'jan1200037c.fits' / original name of this file
TIME = '20:39:19' / FITS file creation time (hh:mm:ss)
EXPTIME = 2.0 / total integration time (s)
DATE-OBS= '01/12/2005' / observation date (mm/dd/yyyy)
OBS-BEG = '20:39:15' / shutter open time (hh:mm:ss)
SHUTTERO= 74355.7 / shutter open time (seconds since 00:00 UT)
OBS-END = '20:39:17' / shutter closing time (hh:mm:ss)
SHUTTERC= 74357.7 / shutter closing time (seconds since 00:00 UT)
IMAGETYP= 'object' / type of the image
CDS-GAIN= 20 / CDS gain setting
HBIN = 2 / horizontal binning
VBIN = 2 / vertical binning
CHANNEL = 'c' / channel name
CHANDESC= 'R_B' / channel description
FILTERS = 'y' / filter used
DETECTOR= 'Lookheed Martin CCD485 #383 4kx4k' / detector used
BIASSEC = '[2078:2100,1:2100]' / overrscan section of the frame
DATASEC = '[1:2046,1:2046]' / data section of the frame
TRIMSEC = '[1:2046,1:2046]' / trim section of the frame
CCDSEC = '[3:2048,3:2048]' / orientation to full format frame
CHIPSIZE= '[1:2200,1:2200]' / original size of full format frame
CHIPDATA= '[1:2048,1:2048]' / data size of full format frame
CHIPOVER= '[2080:2200,2080:2200]' / overscan size of full format frame
WINDOW = '[3:2102,3:2102]' / window parameter
WHEELPOS= 14400 / filter wheel position
CHIPTEMP= -124.8 / (celsius) CCD chip temperature
CHIPTSET= -125.0 / (celsius) CCD chip set temperature
CHIPHEAT= 46.0 / (%) CCD chip heating
CHIPEX = 331.0 / CCD chip LN2 evaporating
PIPEIN = 975.0 / CCD chip LN2 temperature (IN)
PIPEOUT = 644.0 / CCD chip LN2 temperature (OUT)
LN2STAT = 0.0 / CCD chip LN2 status
INSTRSCL= 0.34 / instrument scaling (horizontal)
DSPVER = '4CCDV2.31 09.03.2000' / used DSP version
PATTERN = 'busca010419.ccd' / used CCD pattern
TEMPERAT= 1.9 / WDX temperature
HUMIDITY= 26.0 / WDX humidity
PRESSURE= 781.1 / WDX air pressure
WINDSPEE= 9.0 / WDX wind speed
WINDGUST= 10.2 / WDX wind gust
WINDDIR = 0.0 / WDX wind directionThanks!

Hi,Your parameters look ok. I don't think ccdproc can "remove" sources in images. I will make an off-hand guess that you are judging the results by looking at a display. You may get fooled by the automatic scaling if the result of ccdproc causes the scaling to be way off (say by introducing large values at places where the flat field is nearly zero). When in doubt you should use implot to make line and column cuts to see the real pixel values.If this mystery persists I could take a look at the data which you would have to provide to me.Frank Valdes