vircam_standard_process
[Recipes]

Name:

vircam_standard_process

Purpose:

Reduce a full pawprint of standard field VIRCAM data

Description:

A single pawprint of VIRCAM standard field data in a single filter is corrected for instrumental signature. Any microstep sequences are interleaved into super frames. If interleaving is done then the resulting superframes are dithered into a final stacked image. If interleaving is not done, then then the instrumentally corrected simple images are dithered into the final stacked image. This stacked image is astrometrically and photometrically calibrated against 2mass standards. An additional photometric calibration can be done against a second input source catalogue.

Language:

C

Parameters:

• ipix (int): The minimum allowable size of an object
• thr (float): The detection threshold in sigma above sky
• icrowd (int): If set then the deblending software will be used
• rcore (float): The core radius in pixels
• nb (int): The smoothing box size for background map estimation
• savecat (int): If set, then the catalogues will be saved.
• destripe (int): If set, then the single images will be destriped
• skycor (int): If set, a simple sky background correction will be applied.
• ext (int): The image extension of the input files to be done on this run. If all of the extensions are to be processed, then this should be set to zero.

Input File Types:

The following list gives the file types that can appear in the SOF file. The word in bold is the DO category value.

• MASTER_DARK (required): A master dark frame.
• MASTER_TWILIGHT_FLAT (required): A master twilight flat frame.
• MASTER_CONF or MASTER_BPM (required): A master confidence map for the filter used in the science images. If such is not available, then there is the option to use a master bad pixel mask.
• MASTER_READGAIN_TABLE (required): A readnoise/gain file
• MASTER_CHANNEL_TABLE (required): The channel table.
• STD_FLUX (required): The list of input science images.
• PHOTCAL_TAB (required): A photometric calibration table
• MASTER_2MASS_CATALOGUE (required): A master 2mass catalogue index
• MASTER_REFERENCE_CATALOGUE (required): A second master photometric catalogue index

Output Products:

The following list gives the output data products that are generated by this recipe. The word in bold gives the DPR CATG keyword value for each product:

• Copies of the input science frames that have been corrected for instrumetal signature (SIMPLE_IMAGE_STD)
• An illumination correction table defined from the corrected simple images (ILLCOR_TAB_STD)
• Interleaved superframes (if microstepping was done) and their associated confidence maps (INTERLEAVED_IMAGE_STD and CONFIDENCE_MAP_STD)
• A dithered stacked image and its associated confidence map (JITTERED_IMAGE_STD and CONFIDENCE_MAP_STD)
• A catalogue of objects extracted from the stacked image (OBJECT_CATALOGUE_STD)

Output QC Parameters:

• SATURATION The saturation level in ADUs.
• MEAN_SKY The mean level of the background sky over the image in ADUs.
• SKY_NOISE The RMS of the background sky over the image in ADUs
• NOISE_OBJ The number of noise objects found in the image
• IMAGE_SIZE The average size of stellar images on the image in pixels
• APERTURE_CORR The aperture correction for an aperture of radius rcore.
• ELLIPTICITY The average ellipticity of stellar images on the image
• MAGZPT The photometric zero point
• MAGZERR The internal error in the photometric zero point
• MAGNZPT The number of stars used to determine the magnitude zero point
• ZPT_2MASS Magnitude zeropoint for 2mass standards
• ZPT_STDS Magnitude zeropoint for secondary standard star catalogue
• ZPT_STDS_CAT Name of secondary standard star catalogue
• LIMITING_MAG The limiting magnitude for this image for a 5 sigma detection.
• WCS_DCRVAL1 The offset of the equatorial coordinate represented by CRVAL1 from the raw frame to the reduced one (degrees).
• WCS_DCRVAL2 The offset of the equatorial coordinate represented by CRVAL2 from the raw frame to the reduced one (degrees).
• WCS_DTHETA The change in the WCS coordinate system rotation from the raw to the reduced frame (degrees)
• WCS_SCALE The scale of the pixels in the reduced frames in arcseconds per pixel
• WCS_SHEAR The shear of the astrometric solution in the form of the difference between the rotation of the x solution and the rotation of the y solution (abs(xrot) - abs(yrot) in degrees)
• WCS_RMS The average error in the WCS fit (arcsec)

Notes

None.

Fatal Error Conditions:

• NULL input frameset
• Input frameset headers incorrect meaning that RAW and CALIB frame can't be distinguished
• No science frames in the input frameset
• Required master calibration images and tables are missing
• Unable to save data products

Non-Fatal Error Conditions:

• None

Conditions Leading To Dummy Products:

• Master calibration images either won't load or are flagged as dummy
• The detector for the current image extension is flagged dead in all science frames
• Various processing routines fail.

Author:

Jim Lewis, CASU

Code Reference:

vircam_standard_process.c

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