MIPS : Data Products

MIPS data are delivered to observers as FITS image files through the Leopard archive interface; observers log into the archive interface to obtain their data. Because of the complexity and redundant nature of the MIPS AORs, three distinct types of data are generated by SSC pipeline processing. Observers will be able to select which kinds of data they would like to download through the archive interface.

Basic Calibrated Data products (BCD) for MIPS are data derived from a single data collection event (a DCE, or a single frame exposure). The Basic Calibrated Data are planned to be the most reliable product achievable by automated processing. Some refinement in processing, especially for the Ge:Ga detectors, is ongoing during the first year of the Spitzer mission. BCDs for all AOTs are in the form of FITS images; the SED BCDs are dispersion-corrected and calibrated two-dimensional spectral FITS images. Ge BCD images are corrected for the effects of cosmic ray impacts; cosmic rays are flagged (but not removed) for Si. The total integration time for the individual BCD frames is the observer-specified exposure time (i.e., 3, 4, 10, or 30 seconds), not the total integration time accumulated during the multiple on-source exposures that result from an AOR. No background or sky subtraction is made. BCD products are composed of 2-dimensional FITS image files and a full set of header information keywords, including distortion coefficients, epoch, pointing information, and pipeline and calibration versions. The BCD products are calibrated in MJy/ster.

Post-BCD products (post-BCD) are derived from a full AOR (e.g., a scan map or a dithered photometry observation). These data are the result of combining all individual BCD frames from a single AOR; in the case of photometry mode, the product is an averaged and registered single image suitable for photometric measurements, and in the case of a scan map, the product is a registered mosaic, with first order removal of seams between the component images. MIPS post-BCD products are calibrated in MJy/ster. The post-BCD products are delivered to the observer in the form of a single FITS image file per AOR, and include a full complement of header keywords.

The Raw Data products are the unprocessed array images (in unprocessed counts per pixel). These FITS image files allow the observer direct access to the data, but still contain the difficult-to-calibrate detector behavior inherent to Ge:Ga detector technology for the 70 micron and 160 micron frames. No cosmic ray removal will have been performed.

Additional MIPS pipeline products ultimately derived from the post-BCD products will include a list of extracted point sources. The list includes at least positions within the uncertainties of the spacecraft pointing system and array geometry knowledge, flux density (aperture and profile), signal-to-noise ratio, and associated uncertainties. For data acquired within an AOR, a list of "band-merged" point sources (at 24 and 70 micron) will also be provided as available. This list includes at least flux density (aperture and profile), signal-to-noise ratio, and associated uncertainties. If a band has no detection, a statistically meaningful flux upper limit is estimated from the underlying data frames (when they exist).

Graphical representation of pipelines

• 24 micron science pipeline
• 70 and 160 micron (Ge) science pipeline
• post-BCD pipeline

For more information, see the MIPS Data Handbook, or the MIPS chapter of the SOM

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