After you have constructed your bias frame (Zero???.fits) and corrected dome-flats (Dflat???.fits), it is time to do the initial processing of the MOSAIC object frames using ccdproc. Included here is a sample parameter file to process some I-band images obtained with the MOSAIC-1 camera with science grade CCDs. If you are reducing older data taken with the engineering grade CCDs you might want to include a dark count correction. Note that flatcor=yes, but that sflatco=no, as we have not yet constructed a darksky or twilight flat. Setting xtalkco=yes and specifying a file for xtalkfi= enables the cross-talk correction to be made. Note that currently images have their image header populated with the correct xtalk.dat file under the keyword xtalkfil. You could therefore substitute xtalkfi= !xtalkfil for the path name to the xtalk.dat file.
PACKAGE = mscred TASK = ccdproc images = @objects_I.list List of Mosaic CCD images to process (output = ) List of output processed images (bpmasks= ) List of output bad pixel masks (ccdtype= object) CCD image type to process (noproc = no) List processing steps only? (xtalkco= yes) Apply crosstalk correction? (oversca= yes) Apply overscan strip correction? (trim = yes) Trim the image? (fixpix = yes) Apply bad pixel mask correction? (zerocor= yes) Apply zero level correction? (darkcor= no) Apply dark count correction? (flatcor= yes) Apply flat field correction? (sflatco= no) Apply sky flat field correction? (merge = no) Merge amplifiers from same CCD? (saturat= INDEF) Saturation (+val=e-, -val=ADU) (xtalkfi= mscdb$noao/CCDMosaThin1/xtalk.dat) Crosstalk file (biassec= !biassec) Overscan strip image section (trimsec= !trimsec) Trim data section (fixfile= BPM) List of bad pixel masks (zero = Zero990327.fits) List of zero level calibration images (dark = Dark) List of dark count calibration images (flat = Dflat990327Iwop.fits) List of flat field images (sflat = Sflat*) List of secondary flat field images (minrepl= 1.) Minimum flat field value (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 (fd = ) (fd2 = ) (mode = ql)
After ccdproc has completed you can perform a quick check that your images were actually processed through all the steps you wanted by inspecting a few of the image headers and by running ccdlist. This useful task can be used to generate a file recording the current reduction status: msc> ccdlist @object.list > object_redstatus.ccdlist using the parameter file:
PACKAGE = mscred TASK = ccdlist images = @object.list CCD images to listed (ccdtype= ) CCD image type to be listed (extname= im1) Extension name pattern (names = no) List image names only? (long = no) Long format listing? (mode = ql)This output file will be an up to the moment log of where each image is in the data recution steps. It provides a convienent place to make notes about the individual images during the data reduction steps. We generally update/annotate this listing to keep track of additional processing steps as we move toward our final combined image stacks.
The next step to consider in your reductions is whether or not to try to improve on the correction provided by your dome-flat. This is covered in section III. C..