Data model: photoObj

General Description
The photoObj files contain the full, calibrated outputs of the SDSS imager photometric pipeline. They are parallel with the CAS photoObjAll and photoProfile tables. All "magnitudes" in this file are of the asinh type.
Naming Convention
photoObj-[0-9]{6}-[1-6]-[0-9]{4}\.fits, where [0-9]{6} is a zero-padded six-digit number containing the run number, [1-6] is the camera column ('camcol') and [0-9]{4} is the zero-padded, four-digit frame sequence number.
Approximate Size
3 Mbytes
File Type
Read by Products
Written by Products

HDU0: Header Keywords Only

HDU0 Contains no data, only some required header keywords.

Required Header Keywords
VERSIONstrphoto version used during frames
DERV_VERstrdervish version used
ASTR_VERstrastrom version used
ASTRO_IDstrjob ID and time for astrom
BIAS_IDstrbias version
FRAME_IDstrjob ID and time for frames
KO_VERstrknown objects version used
PS_IDstrPSP time and job id
CREATIMEstrtime of original fpObjc creation
SEEDintseed for photo random number generator
REF_BANDintindex of canonical band
RUNintImaging run number
RERUNintProcessing rerun number
CAMCOLintColumn in the imaging camera
FIELDintField sequence number
FILTERSstrFilter order in arrays
DARK_VARstrper-pixel variances at zero DN
GAINstrmean gains of amps (e/DN)
POBJ_VERstrphotoop version used for photoObj
REDUXstrphoto reductions directory
RESOLVEstrphoto resolve directory
CALIBstrphoto calibration directory
SWEEPstrphoto sweep directory
TREEstrtree version

HDU1: The photoObj Table

Required Header Keywords
TFIELDS139intNumber of columns in table
Required Columns
OBJIDstringUnique SDSS identifier composed from [skyVersion,rerun,run,camcol,field,obj].
PARENTIDstringObject identifier of parent (if object deblended) or BRIGHT detection (if object has one), else 0
FIELDIDstringField identifier composed of [run, camcol, field, rerun, skyversion].
SKYVERSIONint8Layer of catalog (currently only one layer, 0)
MODEint81: primary, 2: secondary, 3: other
CLEANint32Clean photometry flag for point sources (1=clean, 0=unclean).
RUNint32Run number
RERUNstringRerun number
CAMCOLint32Camera column
FIELDint32Field number
IDint32The object id within a field. Usually changes between reruns of the same field
PARENTint32parent ID, if there is one
NCHILDint32Number of children if this is a composite object that has been deblended. BRIGHT (in a flags sense) objects also have nchild == 1, the non-BRIGHT sibling.
OBJC_TYPEint16 Type classification of the object (star, galaxy, cosmic ray, etc.)
OBJC_PROB_PSFfloat32Probability that the object is a star. Currently 0 if type == 3 (galaxy), 1 if type == 6 (star).
OBJC_FLAGSint32photo object attribute flags
OBJC_FLAGS2int32Second set of photo object attribute flags
OBJC_ROWCfloat32Row center position (r-band coordinates) (pix)
OBJC_ROWCERRfloat32Row center position error (r-band coordinates) (pix)
OBJC_COLCfloat32Column center position (r-band coordinates) (pix)
OBJC_COLCERRfloat32Column center position error (r-band coordinates) (pix)
ROWVDEGfloat32Row-component of object's velocity (deg/day)
ROWVDEGERRfloat32Row-component of object's velocity error (deg/day)
COLVDEGfloat32Column-component of object's velocity (deg/day)
COLVDEGERRfloat32Column-component of object's velocity error (deg/day)
ROWCfloat32[5]Row center (pix)
ROWCERRfloat32[5]ERROR Row center error (pix)
COLCfloat32[5]Column center (pix)
COLCERRfloat32[5]Column center error (pix)
PETROTHETAfloat32[5]Petrosian radius (arcsec)
PETROTHETAERRfloat32[5]Petrosian radius error (arcsec)
PETROTH50float32[5]Radius containing 50% of Petrosian flux (arcsec)
PETROTH50ERRfloat32[5]Error in radius with 50% of Petrosian flux error (arcsec)
PETROTH90float32[5]Radius containing 90% of Petrosian flux (arcsec)
PETROTH90ERRfloat32[5]Error in radius with 90% of Petrosian flux error (arcsec)
Qfloat32[5]Stokes Q parameter
QERRfloat32[5]Stokes Q parameter error
Ufloat32[5]Stokes U parameter
UERRfloat32[5]Stokes U parameter error
M_E1float32[5]Adaptive E1 shape measure (pixel coordinates)
M_E2float32[5]Adaptive E2 shape measure (pixel coordinates)
M_E1E1ERRfloat32[5]Covariance in E1/E1 shape measure (pixel coordinates)
M_E1E2ERRfloat32[5]Covariance in E1/E2 shape measure (pixel coordinates)
M_E2E2ERRfloat32[5]Covariance in E2/E2 shape measure (pixel coordinates)
M_RR_CCfloat32[5]Adaptive ( + ) (pixel coordinates)
M_RR_CCERRfloat32[5]Error in adaptive ( + ) (pixel coordinates)
M_CR4float32[5]Adaptive fourth moment of object (pixel coordinates)
M_E1_PSFfloat32[5]Adaptive E1 for PSF (pixel coordinates)
M_E2_PSFfloat32[5]Adaptive E2 for PSF (pixel coordinates)
M_RR_CC_PSFfloat32[5]Adaptive ( + ) for PSF (pixel coordinates)
M_CR4_PSFfloat32[5]Adaptive fourth moment for PSF (pixel coordinates)
THETA_DEVfloat32[5]de Vaucouleurs fit major-axis scale radius, same as half-light or effective radius (arcsec)
THETA_DEVERRfloat32[5]Error in de Vaucouleurs fit major-axis scale radius (arcsec)
AB_DEVfloat32[5]de Vaucouleurs fit b/a axis ratio
AB_DEVERRfloat32[5]de Vaucouleurs fit b/a axis ratio error
THETA_EXPfloat32[5]Exponential fit major-axis scale radius, here defined to be the same as half-light or effective radius (arcsec)
THETA_EXPERRfloat32[5]Error in exponential fit major-axis scale radius (arcsec)
AB_EXPfloat32[5]Exponential fit b/a axis ratio
AB_EXPERRfloat32[5]Exponential fit b/a axis ratio error
FRACDEVfloat32[5]Weight of deV component in deV+Exp model
FLAGSint32[5]Object detection flags per band
FLAGS2int32[5]Second set of detection flags per band
TYPEint32[5]Object type classification per band
PROB_PSFfloat32[5]Probability that the object is a star in each band
NPROFint32[5]Number of used Profile Bins
PROFMEAN_NMGYfloat32[15,5]Calibrated mean flux in each photo annulus, as described in the SDSS imaging pipeline documentation.
PROFERR_NMGYfloat32[15,5]Error in calibrated mean flux in each photo annulus
STAR_LNLfloat32Star ln(likelihood)
EXP_LNLfloat32Exponential disk fit ln(likelihood)
DEV_LNLfloat32de Vaucouleurs fit ln(likelihood)
PSP_STATUSint32[5]PSP output status (see psField file for details).
PIXSCALEfloat32[5]pixel scale, arcsec
RAfloat64J2000 Right Ascension (from r-band, or best other band if r-band if too faint or saturated in r) (deg)
DECfloat64J2000 Declination (from r-band, or best other band if r-band if too faint or saturated in r) (deg)
CXfloat64unit vector for ra+dec
CYfloat64unit vector for ra+dec
CZfloat64unit vector for ra+dec
RAERRfloat64Error in RA (* cos(Dec), that is, proper units) (arcsec)
DECERRfloat64Error in Dec (arcsec)
Lfloat64Galactic longitude (deg)
Bfloat64Galactic latitude (deg)
OFFSETRAfloat32[5]filter position RA minus final RA (* cos(Dec), that is, proper units) (arcsec)
OFFSETDECfloat32[5]filter position Dec minus final Dec (arcsec)
PSF_FWHMfloat32[5]PSF FWHM (arcsec)
MJDint32Date of observation (days)
AIRMASSfloat32[5]Airmass at time of observation
PHI_OFFSETfloat32[5]Degrees to add to CCD-aligned angle to convert to E of N (deg)
PHI_DEV_DEGfloat32[5]deg --/U de Vaucouleurs fit position angle (+N thru E) (deg)
PHI_EXP_DEGfloat32Exponential fit position angle (+N thru E) (deg)
EXTINCTIONfloat32[5]Galactic extinction (SFD) (mag)
SKYFLUXfloat32[5]Sky flux at the center of object (allowing for siblings if blended). (nanomaggies)
SKYFLUX_IVARfloat32[5]Sky flux inverse variance (nanomaggies)
PSFFLUXfloat32[5]PSF flux (nanomaggies)
PSFFLUX_IVARfloat32[5]PSF flux inverse variance (nanomaggies)
PSFMAGfloat32[5]PSF magnitude (mag)
PSFMAGERRfloat32[5]PSF magnitude error (mag)
FIBERFLUXfloat32[5]Flux in 3 arcsec diameter fiber radius (nanomaggies)
FIBERFLUX_IVARfloat32[5]Inverse variance in flux in 3 arcsec diameter fiber radius (nanomaggies)
FIBERMAGfloat32[5]Magnitude in 3 arcsec diameter fiber radius (mag)
FIBERMAGERRfloat32[5]Error in magnitude in 3 arcsec diameter fiber radius (mag)
FIBER2FLUXfloat32[5]Flux in 2 arcsec diameter fiber radius (nanomaggies)
FIBER2FLUX_IVARfloat32[5]Inverse variance in flux in 2 arcsec diameter fiber radius (nanomaggies)
FIBER2MAGfloat32[5]Magnitude in 2 arcsec diameter fiber radius (mag)
FIBER2MAGERRfloat32[5]Error in magnitude in 2 arcsec diameter fiber radius (mag)
CMODELFLUXfloat32[5]DeV+Exp flux; result of fitting coefficients in linear combination of models, with structural parameters fixed based on individual fits (nanomaggies)
CMODELFLUX_IVARfloat32[5]Inverse variance in DeV+Exp flux fit (nanomaggies)
CMODELMAGfloat32[5]DeV+Exp magnitude; see cModelFlux (mag)
CMODELMAGERRfloat32[5]DeV+Exp magnitude error (mag)
MODELFLUXfloat32[5]better of DeV/Exp flux fit; for these measurements, the structural parameters used in every band, are the r-band values, and only the amplitude is varied (nanomaggies)
MODELFLUX_IVARfloat32[5]Inverse variance in better of DeV/Exp flux fit (nanomaggies)
MODELMAGfloat32[5]better of DeV/Exp magnitude fit; see modelFlux (mag)
MODELMAGERRfloat32[5]Error in better of DeV/Exp magnitude fit (mag)
PETROFLUXfloat32[5]Petrosian flux (nanomaggies)
PETROFLUX_IVARfloat32[5]Petrosian flux inverse variance (nanomaggies)
PETROMAGfloat32[5]Petrosian magnitude (mag)
PETROMAGERRfloat32[5]Petrosian magnitude error (mag)
DEVFLUXfloat32[5]nanomaggies (de)
DEVFLUX_IVARfloat32[5]nanomaggies^{-2} (de)
DEVMAGfloat32[5]mag (de)
DEVMAGERRfloat32[5]mag error (de)
EXPFLUXfloat32[5]Exponential fit flux (nanomaggies)
EXPFLUX_IVARfloat32[5]Exponential fit flux inverse variance (nanomaggies)
EXPMAGfloat32[5]Exponential fit magnitude (mag)
EXPMAGERRfloat32[5]Exponential fit magnitude error (mag)
APERFLUXfloat32[5,8]Aperture flux within [0.223, 0.670, 1.024, 1.745, 2.972, 4.584, 7.359, 11.306] arcsec radii in each band (nanomaggies), as described in the SDSS imaging pipeline documentation.
APERFLUX_IVARfloat32[5,8]Inverse variance of aperture flux values (1/nanomaggies2)
CLOUDCAMint32[5]Cloud camera status for observation
CALIB_STATUSint32[5]Calibration status of object
NMGYPERCOUNTfloat32[5]nanomaggies per count (nmgy)
NMGYPERCOUNT_IVARfloat32[5]inverse variance on nanomaggies per count (nmgy)
TAIfloat64[5]time of observation (TAI) in each filter (sec)
RESOLVE_STATUSint32Resolve status of object
THING_IDint32Unique identifier from global resolve
IFIELDint32The 0-indexed position of the field within window_flist.fits.
BALKAN_IDint32What balkan object is in from window
NOBSERVEint32Number of observations of this position on the sky
NDETECTint32Number of detections of this object
NEDGEint32Number of observations of this object near an edge (not included in nObserve or nDetect)
SCOREfloat32Quality of field (0-1)

Example File