General notes

Though efforts have been made to avoid this from occurring, where header keyword names are longer than the usual 8 character maximum, the HIERARCH convention will be used.

Celestial coordinates are in ICRS.

Magnitudes are AB magnitudes (flux zero point is 3631 Jy).

Unless otherwise noted, error values are statistical only, and include no contribution by systematic errors.

Primary header

The primary header will not contain any information beyond that written automatically by cfitsio, and is present only for compliance with the FITS standard.

FITS table

The FITS table will include all detections within an exposure.

Duplicates from overlapping skycells will have been filtered out by IPP, with the measurements from the source closest to the centre of a skycell included (and all others discarded).

Header

The header will contain information relevant to the exposure as a whole.

• Version information
  • SWSOURCE (string): source of software (e.g., "60eb6cdc-a59c-4636-a4e0-dba66a9721fd")
  • SWVERSN (string): version of software (e.g., "trunk/ppMops@24658")

• Provenance information
  • EXP_NAME (string): Exposure name (e.g., "o1234g5678")
  • EXP_ID (S64): Exposure identifier
  • CHIP_ID (S64): Chip stage identifier
  • CAM_ID (S64): Camera stage identifier
  • FAKE_ID (S64): Fake stage identifier
  • WARP_ID (S64): Warp stage identifier
  • DIFF_ID (S64): Diff stage identifier
  • DIFF_POS (boolean): Sense of subtraction; T for forward, F for backward

• Exposure details
  • MJD-OBS (F64): TAI MJD of exposure mid-point
  • RA (string): Reported Right Ascension of telescope boresight, sexagesimal hours (e.g., "12:34:56.789")
  • DEC (string): Reported Declination of telescope boresight, sexagesimal degrees (e.g., "-12:34:56.78")
  • TEL_ALT (F64): Reported telescope altitude, degrees
  • TEL_AZ (F64): Reported telescope azimuth, degrees
  • EXPTIME (F32): Exposure time, seconds
  • ROTANGLE (F64): Rotator angle, degrees
  • FILTER (string): Filter name (e.g., "r.00000")
  • AIRMASS (F32): Airmass for exposure
  • OBSCODE (string): IAU observatory code (i.e., "F51" for PS1)
  • SEEING (F32): Measured seeing at diff stage, arcsec
  • MAGZP (F32): Magnitude zero point
  • MAGZPERR (F32): Error in magnitude zero point
  • ASTRORMS (F32): RMS of astrometric fit, arcsec

• Detection efficiency
  • DE_MAGnn (F32): Magnitude (calibrated) for detection efficiency
  • DE_EFFnn (F32): Detection efficiency (0..1)

Current limitations

The IPP is not yet calculating detection efficiencies (it is still being developed). Further, it is not yet clear how to merge the detection efficiency measurements for different skycells. Until these issues are resolved, the detection efficiency values will be fake.

Differences from original ICD

• SWSOURCE, SWVERSN has replaced TABLEVER which was never defined
• All of the "Provenance information" has replaced FPA_ID, for better tracking of the source of each detection
• SEEING and MAGZP added as indicators of the quality of the exposure
• MAGZPERR added to make absolute (i.e., across exposures) magnitude errors more accurate
• ASTRORMS added to make absolute (i.e., across exposures) astrometry errors more accurate
• DE_MAGnn and DE_EFFnn replace DE1 through DE10, which were never well defined

Table

The table will contain information relevant to the individual detections within the exposure.

• RA (F64): Right Ascension of detection centre, degrees
• RA_ERR (F64): Error in RA, degrees
• DEC (F64): Declination of detection centre, degrees
• DEC_ERR (F64): Error in DEC, degrees
• MAG (F32): Calibrated magnitude of detection
• MAG_ERR (F32): Error in MAG
• STARPSF (F32): A PSF/extended source separator
• ANGLE (F64): Angle of trail fit to source, degrees E of N
• ANGLE_ERR (F64): Error in ANGLE, degrees
• LENGTH (F32): Length of trail fit to source, degrees
• LENGTH_ERR (F32): Error in LENGTH, degrees
• FLAGS (S32): IPP detection flags, bit mask
• DIFF_SKYFILE_ID (S64): IPP diff_skyfile_id for source

Current limitations

The IPP is not yet fitting trails to sources in the difference images. Until this is being done, the ANGLE, ANGLE_ERR, LENGTH and LENGTH_ERR values will be zero.

The value being written as STARPSF is EXT_NSIGMA from the IPP CMF files; it is not clear that this is what MOPS wants, but this is probably irrelevant until the trail fitting has been implemented.

Differences from original ICD

• RA_DEG, DEC_DEG renamed RA, DEC to match apparent naming policy
• *_SIG renamed *_ERR to be more clear
• ANG, ANG_SIG, LEN, LEN_SIG spelled out as ANGLE, ANGLE_ERR, LENGTH, LENGTH_ERR
• FLUX, FLUX_SIG renamed MAG, MAG_ERR since IPP writes magnitudes
• FLAGS added to allow additional weeding out of bad detections
• DIFF_SKYFILE_ID added to allow trace back to IPP diff skyfile, for postage stamps