WISE Software Interface Specification; icl05; (WSDC D-I194) Written by F. Masci, internal version 3.1, 12/21/2011 Interface Name: Bad-pixel / Frame Processing Status Mask Type of Interface: FITS-Formatted 32-bit pixel status image recording prior information from ground characterization and dynamic masking from single frame processing. Read By: MDET, WPHOT _____________________________ K. Marsh, T. Jarrett (Source Detection and Photometry modules) AWAIC, AWOD _____________________________ F. Masci (A WISE Astronomical Image Co-adder) (A WISE Outlier Detector) ScanSync PSF ____________________________ J. Fowler (Software for generating PSFs for PSFMoments program to assess scan-mirror synchronization) Written/Updated By: ICAL ____________________________________ F. Masci (Instrumental Calibration Pipeline modules) DESCRIPTION: This is an image mask used to store pixel status information applicable to a frame acquired from a single exposure. It will store "static" bad-pixel information characterized a-priori on the ground as well as details of "dynamic" processing. The mask will be initialized in the ICAL pipeline and progressively updated therein. It will be used downstream for omitting specific pixels which have been tagged as "bad" or unsuitable for scientific use, and will serve as an informational diagnostic for track-back analyses and quality assurance. The mask is a single plane of 1016 x 1016 pixels for bands 1, 2 and 3; and 508 x 508 pixels for band 4. This corresponds to the active region of a WISE frame, i.e., with the reference-pixel border discarded. The pixels are represented as 32-bit signed integers (BITPIX = 32). The status of certain conditions will be assigned to individual bits. Useable bits are numbered from zero (the LSB) to 30. The sign bit, bit 31, is not used. Each status bit describes a specific condition of the pixel; if the bit has the value 1, the condition is in effect; zero implies that the condition is not in effect. FITS HEADER: The FITS header contains the following lines, where angle brackets indicate information whose literal content depends on actual execution circumstances. SIMPLE = T BITPIX = 32 NAXIS = 2 NAXIS1 = 1016 NAXIS2 = 1016 FRMFILE = '.fits' / Name of corresponding output frame file HISTORY = v. : ~ ~ ~ ~ END NOTES: * The HISTORY line records the name, version, and local execution date/time of the module or subsystem that read/updated the mask. There shall be one history line for every module/subsystem that read and/or updated the mask. * The above header pertains to either band 1, 2 or 3 where NAXIS1 = NAXIS2 = 1016. A band 4 frame will have NAXIS1 = NAXIS2 = 508. * The header also contains a copy of all (non-mask/FITS specific) cards from the final processed frame. This may include information from steps after the instrumental calibration pipeline has run, e.g., a refined WCS from the SFPRex and MFPRex modules. This will assist in track-back analyses. FILE NAME: There will be one pixel status mask for each processed intensity frame. Given a frame processed through the instrumental calibration pipeline has generic name: -w-int-1b.fits, the corresponding mask is named -w-msk-1b.fits.gz, i.e., in compressed format. STATUS BIT DEFINITIONS: Bit # Condition ----- ----------------------------------------------------------------- 0 from static mask: excessively noisy due to high dark current alone 1 from static mask: generally noisy [includes bit 0] 2 from static mask: dead or very low responsivity 3 from static mask: low responsivity or low dark current 4 from static mask: high responsivity or high dark current 5 from static mask: saturated anywhere in ramp 6 from static mask: high, uncertain, or unreliable non-linearity 7 from static mask: known broken pixel/-'ve SUR or excessively noisy responsivity estimate [may include bit 1] 8 reserved 9 broken pixel or intrinsically -'ve SUR (downlink value = 32767) 10 saturated in sample read 1 (downlink value = 32753) 11 saturated in sample read 2 (downlink value = 32754) 12 saturated in sample read 3 (downlink value = 32755) 13 saturated in sample read 4 (downlink value = 32756) 14 saturated in sample read 5 (downlink value = 32757) 15 saturated in sample read 6 (downlink value = 32758) 16 saturated in sample read 7 (downlink value = 32759) 17 saturated in sample read 8 (downlink value = 32760) 18 saturated in sample read 9 (downlink value = 32761) 19 for w1,w2,w3 in 3-band cryo period; set by ical to tag hard saturated pixels and values equal to DEB bias levels: 128 (for w1,w2) or 256 (for w3). Could overlap with bit 10 for heavily saturated sources, when properly tagged as saturated in frame pipeline 20 reserved 21 new/transient bad pixel from dynamic masking (dynasky) 22 reserved 23 for w3 only in 3-band cryo period; set during multiframe processing due to errant static split-droop residuals from single-frame processing 24 reserved 25 reserved 26 non-linearity correction unreliable (ical) 27 contains cosmic-ray or outlier that cannot be classified (from temporal outlier rejection in multi-frame pipeline) 28 contains positive or negative spike-outlier (ical) 29 reserved 30 reserved 31 not used: sign bit NOTES: * bits 0 - 7 (the first eight) are propagated from a static (8-bit) calibration mask. The remaining bits: 8 - 30, where defined, are set dynamically on a per-frame basis during processing. * bit 3: low responsivity refers to a pixel which is not quite dead. Truly dead or unresponsive pixels are covered by bit 2. * bit 21: new/transient bad pixels are detected and flagged using dynamic masking in the "dynacal" calibration pipeline (dynasky module). * bit 27: this is a generic condition pertaining to any pixel-outlier detected using the temporal stacking method (awod module) in the multi-frame pipeline. It will tag transients inadvertently missed by other methods, as well as sources that have moved or varied appreciably between overlapping frames. * bit 28: single spike outliers are detected at the frame level in the instrumental calibration pipeline. There may be redundancy with outliers detected using the temporal method (bit 27). * the bits used to exclude pixels from v4.0, v4.1 pipeline photometry (pass 2 frame and multiframe processing respectively) was: 0,1,2,3,4,5,6,9,10,11,12,13,14,15,16,17,18,21,27,28. For 3-band cryo processing (v4.5, v4.6), it was: 0,1,2,3,4,5,6,9,10,11,12,13,14,15,16,17,18,19,21,23,27,28