#### Preprocessing ## To make list containing all bias frames run following commands on the terminal ram> ls bi*fits > bias_list ## where 'bias_list' is list of all bias files cl > noao > imred > ccdred ccdred> epar zerocombine Image Reduction and Analysis Facility PACKAGE = ccdred TASK = zerocombine input = @bias_list List of zero level images to combine (output = mbias.fits) Output zero level name (combine= average) Type of combine operation (reject = minmax) Type of rejection (ccdtype= ) CCD image type to combine (process= no) Process images before combining? (delete = no) Delete input images after combining? (clobber= no) Clobber existing output image? (scale = none) Image scaling (statsec= ) Image section for computing statistics (nlow = 0) minmax: Number of low pixels to reject (nhigh = 1) minmax: Number of high pixels to reject (nkeep = 1) Minimum to keep (pos) or maximum to reject (neg) (mclip = yes) Use median in sigma clipping algorithms? (lsigma = 3.) Lower sigma clipping factor (hsigma = 3.) Upper sigma clipping factor (rdnoise= 0.53) ccdclip: CCD readout noise (electrons) (gain = 10.) ccdclip: CCD gain (electrons/DN) (snoise = 0.) ccdclip: Sensitivity noise (fraction) (pclip = -0.5) pclip: Percentile clipping parameter (blank = 0.) Value if there are no pixels (mode = ql) ## mbias.fits if the master bias frame. ## Subtracting master bias from all the raw flat frames # make a list of flat frames in each filter ram> ls flatv* > flv_lst ccdred> epar ccdproc Image Reduction and Analysis Facility PACKAGE = ccdred TASK = ccdproc images = @flv_list List of CCD images to correct (output = b//@flv_list 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= no) 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 = mbias.fits) Zero level calibration image (dark = ) Dark count calibration image (flat = ) 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) # will give list of bias subtrated flat frames with prefix b. ## Making master flat ## make a list of bias subtracted flat frames ram> ls bflatv* > bflv_list Image Reduction and Analysis Facility PACKAGE = ccdred TASK = zerocombine input = @bflv_list List of zero level images to combine (output = mflatv.fits) Output zero level name (combine= median ) Type of combine operation (reject = minmax) Type of rejection (ccdtype= ) CCD image type to combine (process= no) Process images before combining? (delete = no) Delete input images after combining? (clobber= no) Clobber existing output image? (scale = none) Image scaling (statsec= ) Image section for computing statistics (nlow = 0) minmax: Number of low pixels to reject (nhigh = 1) minmax: Number of high pixels to reject (nkeep = 1) Minimum to keep (pos) or maximum to reject (neg) (mclip = yes) Use median in sigma clipping algorithms? (lsigma = 3.) Lower sigma clipping factor (hsigma = 3.) Upper sigma clipping factor (rdnoise= 0.53) ccdclip: CCD readout noise (electrons) (gain = 10.) ccdclip: CCD gain (electrons/DN) (snoise = 0.) ccdclip: Sensitivity noise (fraction) (pclip = -0.5) pclip: Percentile clipping parameter (blank = 0.) Value if there are no pixels (ode = ql) # will give you master flat in v filter. # In the same way master flats can be made for other filters also. ## Cleaning science frames ### Once master bias and master flats are made, they can be used to create clean science frames. Task 'ccdproc' can again be used to do that but this time with both zero correction and flat corretion. ## make list of raw science frames ram> ls ngc1893v*fits > n1893_list # NGC 1893 is the target Image Reduction and Analysis Facility PACKAGE = ccdred TASK = ccdproc images = @n1893_list List of CCD images to correct (output = c//@n1893_list 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 = mbias.fits) Zero level calibration image (dark = ) Dark count calibration image (flat = mflat.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) # will give a list of cleaned science frames with prefix c. ### Cosmic ray ### for long exposure frames images could be affeted by cosmic ray hits which need to be removed before performing photometry (aperture/psf). Task 'cosmicray' can be used to do that crutil > epar cosmicrays Image Reduction and Analysis Facility PACKAGE = crutil TASK = cosmicrays input = @cosmic_list List of images in which to detect cosmic rays output = cr@cosmic_list List of cosmic ray replaced output images (optio (crmasks= ) List of bad pixel masks (optional) (thresho= 25.) Detection threshold above mean (fluxrat= 2.) Flux ratio threshold (in percent) (npasses= 5) Number of detection passes (window = 5) Size of detection window (interac= yes) Examine parameters interactively? (train = no) Use training objects? (objects= ) Cursor list of training objects (savefil= ) File to save train objects (plotfil= ) Plot file (graphic= stdgraph) Interactive graphics output device (cursor = ) Graphics cursor input answer = Review parameters for a particular image? (mode = ql) # will give a list of cosmic ray removed cleaned science frames with prefix cr. ~