WISE Data Level Definitions

WISE Science Data Level Definitions

Excerpted from the WISE Science Data System Functional Design Document (WSDC D-D001).

Level Image Data Extracted Source Data Notes

Downlink Telemetry Encoded downlink transfer frames. N/A Generated by spacecraft MUB, donwlinked via TDRSS to White Sands. Input for High-Rate Data Processor.

Source Data Packets Packetized, Rice-compressed science data and engineering telemetry. N/A Produced by WISE High-Rate Data Processor @ White Sands and NAV system at JPL. Transferred to WSDC following each downlink.

Raw Frames Decompressed raw pixel data in FITS format. 1024x1024 pix (W1, W2, W3), 512x512 pix (W4) @ 16b/pix. Minimal header. N/A Transient product. Generated during INGEST processing as step to Level 0.

Level 0 Decompressed raw pixel data in FITS format. 1024x1024 pix (W1, W2, W3, W4) @ 32b/pix. Engineering telemetry mapped to headers. N/A Produced by WSDC INGEST subystem. Basic Level 0 archive format.

Level 1a Instrumental pixel-calibrated frame-sets (dark-subtracted, reference pixel corrected, flat-fielded, illumination-corrected, linearized, droop-corrected, etc.). FITS format, 1016x1016 pix @ 32 b/pix (reference pixels trimmed). Headers updated to reflect instrumental pixel calibration. Produced by SFICAL in Scan/Frame Pipeline. List of "sources" detected on Level 1a frames. One set per band. Frame pixel coordinates, instrumental magnitudes, conservative SNR threshold (SNR>7 (TBD)). Generated by SDET as input for PREX. Transient products - not stored. Generated as step to Level 1B.

Level 1b FITS format frames. Pixel values and sizes the same as Level 1a. Headers updated with reconstructed WCS values (including distortion corrections) and photometric calibration zeropoint keyword values. Generated using PREX and PCAL outputs. Input for AWAIC, PHOT. Calibrated frameset (single-epoch), band-merged source lists. Reconstructed equatorial coordinates, calibrated photometry, in-scan artifact flagging, solar-system object associations. Generated by MDET, PHOT, PCAL, ARTID, SSOFIND (TBR). Loaded into Level 1 Source Working Database. Basic Level 1 Ops Archive.

Level 2a FITS format frames. Level 1a frame that has been resampled for 4-band registration and possibly 2x upsampled for distortion-correction. Reference pixels trimmed, 2032x2032 pix @ 32 b/pix. N/A Transient products - not stored. Generated as input for MDET. Also generated for QA and visualization purposes on demand.

Level 2b FITS format coadded images. Level 1b frame that has been resampled for 4-band registration and possibly 2x upsampled for distortion-correction. Reference pixels trimmed, 2032x2032 pix @ 32 b/pix. Updated WCS and photometric calibration information in headers. Generated by AWAIC in COADD pipe. N/A Transient products - not stored. Generated as input for MDET. Also generated for QA and visualization purposes on demand.

Level 3 FITS format coadded images. Background level-matched, throughput scaled, 4-band registered, upsampled pixels. Updated WCS and photometric zero point information in headers. Generated on a pre-defined spatial tiling and pixel scale by AWAIC, MFPREX and PCAL in Multiframe pipeline. "Deep" coadd source lists. Reconstructed equatorial coordinates, calibrated photometry and uncertainties, artifact flagging, confirmation statistics. Generated by MDET, PHOT in Multiframe Pipeline. Loaded into Level 3 Source Working Database. Basic Level 3 archive formats. Input data for FPG system.

Release Products Atlas Images. Subset of Level 3 images. Possible updates/additions to header keywords generated during FPG. Source Catalog. Subset of Level 3 deep coadd source lists. Final calibration and column updates generated during FPG. WISE Preliminary and Final Release formats served via IRSA interfaces. Generated by FPG.

Level	Image Data	Extracted Source Data	Notes
Downlink Telemetry	Encoded downlink transfer frames.	N/A	Generated by spacecraft MUB, donwlinked via TDRSS to White Sands. Input for High-Rate Data Processor.
Source Data Packets	Packetized, Rice-compressed science data and engineering telemetry.	N/A	Produced by WISE High-Rate Data Processor @ White Sands and NAV system at JPL. Transferred to WSDC following each downlink.
Raw Frames	Decompressed raw pixel data in FITS format. 1024x1024 pix (W1, W2, W3), 512x512 pix (W4) @ 16b/pix. Minimal header.	N/A	Transient product. Generated during INGEST processing as step to Level 0.
Level 0	Decompressed raw pixel data in FITS format. 1024x1024 pix (W1, W2, W3, W4) @ 32b/pix. Engineering telemetry mapped to headers.	N/A	Produced by WSDC INGEST subystem. Basic Level 0 archive format.
Level 1a	Instrumental pixel-calibrated frame-sets (dark-subtracted, reference pixel corrected, flat-fielded, illumination-corrected, linearized, droop-corrected, etc.). FITS format, 1016x1016 pix @ 32 b/pix (reference pixels trimmed). Headers updated to reflect instrumental pixel calibration. Produced by SFICAL in Scan/Frame Pipeline.	List of "sources" detected on Level 1a frames. One set per band. Frame pixel coordinates, instrumental magnitudes, conservative SNR threshold (SNR>7 (TBD)). Generated by SDET as input for PREX.	Transient products - not stored. Generated as step to Level 1B.
Level 1b	FITS format frames. Pixel values and sizes the same as Level 1a. Headers updated with reconstructed WCS values (including distortion corrections) and photometric calibration zeropoint keyword values. Generated using PREX and PCAL outputs. Input for AWAIC, PHOT.	Calibrated frameset (single-epoch), band-merged source lists. Reconstructed equatorial coordinates, calibrated photometry, in-scan artifact flagging, solar-system object associations. Generated by MDET, PHOT, PCAL, ARTID, SSOFIND (TBR). Loaded into Level 1 Source Working Database.	Basic Level 1 Ops Archive.
Level 2a	FITS format frames. Level 1a frame that has been resampled for 4-band registration and possibly 2x upsampled for distortion-correction. Reference pixels trimmed, 2032x2032 pix @ 32 b/pix.	N/A	Transient products - not stored. Generated as input for MDET. Also generated for QA and visualization purposes on demand.
Level 2b	FITS format coadded images. Level 1b frame that has been resampled for 4-band registration and possibly 2x upsampled for distortion-correction. Reference pixels trimmed, 2032x2032 pix @ 32 b/pix. Updated WCS and photometric calibration information in headers. Generated by AWAIC in COADD pipe.	N/A	Transient products - not stored. Generated as input for MDET. Also generated for QA and visualization purposes on demand.
Level 3	FITS format coadded images. Background level-matched, throughput scaled, 4-band registered, upsampled pixels. Updated WCS and photometric zero point information in headers. Generated on a pre-defined spatial tiling and pixel scale by AWAIC, MFPREX and PCAL in Multiframe pipeline.	"Deep" coadd source lists. Reconstructed equatorial coordinates, calibrated photometry and uncertainties, artifact flagging, confirmation statistics. Generated by MDET, PHOT in Multiframe Pipeline. Loaded into Level 3 Source Working Database.	Basic Level 3 archive formats. Input data for FPG system.
Release Products	Atlas Images. Subset of Level 3 images. Possible updates/additions to header keywords generated during FPG.	Source Catalog. Subset of Level 3 deep coadd source lists. Final calibration and column updates generated during FPG.	WISE Preliminary and Final Release formats served via IRSA interfaces. Generated by FPG.

Glossary

coadd - Image produced by optimally combining one or more Level 1 frames. Single band.

coaddset - Set of four corresponding coadds, one in each WISE band (W1, W2, W3, W4)

frame - Detector data from a single exposure. Single-band L0 or L1 image.

frameset - Set of four corresponding frames, one in each WISE band (W1, W2, W3, W4)

Last update - 7 March 2008
R. Cutri - IPAC