Data Model: cat

General Description
cat catalogue files contain the crowdsource outputs for the exposure level processing. A CCD_HDR/CAT/PSF extension is present for each CCD present in the exposure. For most exposures, this is 62. Only S29 is shown in the data model for clarity. In addition to the true exposures, one CCD per exposure is reprocessed after injected sythetic sources. All of the same extensions are present for that injected CCD under the name CCDI. One further extension is saved for the injected CCD to record the ground truth values for the synthetic injections.
Naming Convention
EXPOSURE_NAME.cat.fits, where the EXPOSURE_NAME is the name of the ooi file being processed.
Approximate Size
251 MB
File Type
FITS
Sections

HDU0: PRIMARY

Header that is a direct copy of the header for the exposure file from which this catalogue was generated. See ooi model.

HDU1: S29_HDR

Nearly identical copy of the CCD header for the exposure file from which this catalogue was generated. See ooi model. Only rows added by crowdsource are shown here.

Header Table
KeyValueUnitComment
GAINCRWD3.735677480697632e-/ADUemperical gain (counts times inverse variance)
SKYCRWD293.1651611328125ADUmedian sky level across CCD
FWHMCRWD5.838581562042236pixelsmedian full-width at half-maximum of PSF for all detections in the CCD

HDU2: S29_PSF

Parameters for a PSF model fit to this CCD of the exposure file. Parameters characterize linear variation of both a Moffat profile and freely fit core model across the CCD coordinates.

HDU Type
BINARY TABLE
HDU Size
3 MB
Data Table
NameTypeUnitDescription
OFFSETfloat32[2][DEFUNCT] always (0,0)
STAMPfloat32[511,511,2,2]Full PSF model sampled at the largest grid size (511x511 pixels) at each of the corners of the CCD (as indexed by AXIS 3 and 4)
CONVPARAMfloat32[13]Convolutional parameters for Moffat model and their linear variation (FWHM, dFWHMx, dFWHMy, yy, dyy_x, dyy_y, dxy, dxy_x, dxy_y, norm, unused, unused, unused)
RESPARAMfloat32[9,9,3]Residual model freely fit to the 9x9 pixels of the PSF core. Model varies linearly over the CCD chip so AXIS=3 encodes the constant, dx, and dy parameters.

HDU3: S29_CAT

Output catalogue from crowdsource processing of a given CCD in the exposure

HDU Type
BINARY TABLE
HDU Size
39 KB
Data Table
NameTypeUnitDescription
Xfloat64pixelsx coordinate
Yfloat64pixelsy coordinate
FLUXfloat32ADUraw flux
PASSNOfloat64iteration at which source was found
DXfloat32pixelsx uncertainty
DYfloat32pixelsy uncertainty
DFLUXfloat32ADUflux uncertainty (statistical only)
QFfloat32"quality factor" based on PSF-weighted fraction of pixels contributing to the detection. 0 < qf <1 ranges bad < qf < good
RCHI2float32average \(\chi^2\) per pixel, weighted by PSF
FRACFLUXfloat32fraction of flux in this object's PSF that comes from this object
FLUXLBSfloat32[DEFUNCT] flux with attempt at local background subtraction (Backwards compatability only)
DFLUXLBSfloat32[DEFUNCT] fluxlbs uncertainty (Backwards compatability only)
FWHMfloat32pixelsfull-width at half-maximum of PSF
SPREAD_MODELfloat32sextractor-like spread_model; positive means the source is broader than a PSF
DSPREAD_MODELfloat32uncertainty in sextractor spread_model
FLUXISOfloat32ADUflux derived from linear least squares fit to neighbor-subtracted image; significant difference from ordinary flux indicates a convergence issue
XISOfloat64pixelsx coordinate derived from linear least squares fit to neighbor-subtracted image; significant difference from ordinary x indicates a convergence issue
YISOfloat64pixelsy coordinate derived from linear least squares fit to neighbor-subtracted image; significant difference from ordinary y indicates a convergence issue
FLAGSint32DECam Community Pipeline flags at central pixel from upstream image processing
SKYfloat32ADUsky level at central pixel
RAfloat64degreeright ascension
DECfloat64degreedeclination
DECAPSIDint64unique object id (internal to each data release)
GAINfloat32e-/ADUemperical gain (counts times inverse variance)
PRNfloat32probability central pixel in "nebulosity" class
PRLfloat32probability central pixel in "light nebulosity" class
PRRfloat32probability central pixel in "regular" class
PREfloat32probability central pixel in "error" class

HDU4: S24I_MCK

Catalogue of ground truth values for synthetic sources injected into the CCD specified in the extension name to obtain CCDI.

HDU Type
BINARY TABLE
HDU Size
1 KB
Data Table
NameTypeUnitDescription
Xfloat64pixelsx coordinate
Yfloat64pixelsy coordinate
FLUXfloat64ADU flux (sum over 59x59 pixel region of noisy draw)
FLUXFULLfloat64ADU flux (sum over 511x511 pixel region of noisy draw)
PSFWT_FLUXfloat64ADUPSF-weigted flux (of noisy draw over 511x511 pixel region)
AMPfloat64ADUground truth flux before noise and PSF truncation

Examples

An example cat catalogue file is linked here: c4d_190503_101550_ooi_g_v1.cat.fits