Common Vocabulary
LSST Data Management
This document defines common vocabulary that should be used when naming columns in database schema and variables in transient classes. It also defines units and types.
Names for columns/attributes defining errors were omitted. To build them, append "Err" after columns' name (eg raErr, declErr). All error columns use the same units as the columns, for which the error is defined [Is this fair to assume?]
First moments seem to be missing, should they be added?
A columns called probability have tablespecific meaning, for example in PhotoZ table it means probability that given object has a photo z.
name  unit  type  ucd  description  comments

ra  degrees  double   Right ascension 

decl  degrees  double   Declination  dec is a reserved word in most DBMSes

muRa  arcsec/year  double   Derived proper motion  mu_alpha*cos(decl)

muDecl  arcsec/year  double   Derived proper motion  mu_delta

uPosErrA  arcsec  float   Large dimension of the position error ellipse, assuming gaussian scatter  for u filter

uPosErrB  arcsec  float   Small dimension of the position error ellipse, assuming gaussian scatter  for u filter

uPosErrTheta  degrees  float   Orientation of the position error ellipse  for u filter

parallax   float   Derived parallax for the object 

radesys   string(5)   Type of WCS used  Obsolete in ICRS

equinox   float   Equinox of the WCS  Obsolete in ICRS

ctype1   string(20)   Coordinate projection type, axis 1 

ctype2   string(20)   Coordinate projection type, axis 2 

crpix1   float   Coordinate reference pixel, axis 1 

crpix2   float   Coordinate reference pixel, axis 2 

crval1   double   Coordinate value 1 @reference pixel 

crval2   double   Coordinate value 2 @reference pixel 

cunit1   varchar(10)   X axis units 

cunit2   varchar(10)   Y axis units 

cdelt1   float    Obsolete by cd_xx terms?

cdelt2   float    Obsolete by cd_xx terms?

cd11   float   First derivative of coordinate 1 w.r.t. axis 1 

cd21   float   First derivative of coordinate 2 w.r.t. axis 1 

cd12   float   First derivative of coordinate 1 w.r.t. axis 2 

cd22   float   First derivative of coordinate 2 w.r.t. axis 2 

ra_ll  degrees  double   Ra for the lowleft corner  probably something more fancy needed

decl_ll  degrees  double   Decl for the lowleft corner  probably something more fancy needed

ra_lr  degrees  double   Ra for the lowright corner  probably something more fancy needed

decl_lr  degrees  double   Decl for the lowright corner  probably something more fancy needed

ra_ul  degrees  double   Ra for the upperleft corner  probably something more fancy needed

decl_ul  degrees  double   Decl for the upperleft corner  probably something more fancy needed

ra_ur  degrees  double   Ra for the upperright corner  probably something more fancy needed

decl_ur  degrees  double   Decl for the upperright corner  probably something more fancy needed

dateObs   datetime   Date/Time? of observation start (UTC) 

taiObs   datetime   time of shutter open  international atomic time

mjdObs   double   MJD of observation start 

expTime   float   Duration of exposure for this particular element, eg Amplifier, CCD 

darkTime   float   Total elapsed time from exposure start to end of read 

taiDark   double   Time of shutter closed  during the exposure, if there was such an occasion; see Kem Cook for details. International atomic time. There also could be a situation when the shutter was closed and reopened multiple times during the exposure. In this case, a more complicated data structure is needed?

taiMidPoint   double   If a DIASource corresponds to a single exposure, taiMidPoint represents tai time of the middle of exposure. For multiple exposures, this is middle of beginningoffirstexposure to endoflastexposure. 

taiRange   float   If a DIASource corresponds to a single exposure, taiRange equals to exposure length. If DIASoure corresponds to multiple exposures, its taiRange equals to endoflastexposure minus beginningoffirstexposure. 

earliestObsTime   datetime   Time of the first observation of given object 

latestObsTime   datetime   Time of the last observation of given object 

timeGenerated   datetime   Date/time when alert was generated 

zd   float   Zenith distance at observation midpoint 

airmass   float   Airmass value for the Amp reference pixel  preferably center, but not guaranteed

temperature  celsius  float   

wavelength   float   Wavelength 

telAngle  degrees  float   Orientation angle of the telescope w.r.t sky  This is different from camera orientation w.r.t sky (encapsulated in WCS), since telescope is on altaz mount

azimuth  degrees  float   Azimuth of observation  Preferably at center of exposure at center of image and including refraction correction, but none of this is guaranteed

alt  degrees  float   Altitude of observation  Preferably at center of observation at center of image and including refraction correction, but none of this is guaranteed

elevation  degrees  float   [Same as alt?] 

zpt   double   Photometric zero point magnitude 

apDia  pixels  float   Diameter of aperture 

photoFlam   float   Inverse sensitivity 

photoZP   float   System photometric zeropoint 

psf_nstar   int32   Number of stars used for PSF measurement 

psf_apcorr   float   Photometric error due to imperfect PSF model (aperture correction) 

psf_sigma1   float   Inner Gaussian sigma for the composite fit (XXX) 

psf_sigma2   float   Outer Gaussian sigma for the composite fit (XXX) 

psf_b   float   Ratio of inner PSF to outer PSF (XXX) 

psf_b_2G   float   Ratio of Gaussian 2 to Gaussian 1 at origin (XXX) 

psf_p0   float   The value of the power law at the origin (XXX) 

psf_beta   float   The slope of the power law (XXX) 

psf_sigmap   float   Width parameter for the power law (XXX) 

psf_nprof   float   Number of profile bins (XXX) 

psf_fwhm   float   Effective PSF width 

psf_sigma_x   float   

psf_sigma_y   float   

psf_posAngle   float   

psf_peak   float   

psf_x0   float   

psf_x1   float   

chi2   float   Chisquare value for the PSF fit

uMagnitude   double   magnitude (weighted average)  for u filter

uPetroMag   double   petrosian magnitude  for u filter

uApMag   double   aperture magnitude  for u filter

uApMag   double   aperture magnitude for u filter 

psfMag   double   PSF magnitude of the object 

apMag   double   Aperture magnitude 

modelMag   double   Model magnitude (adaptive 2D gauss) 

uIxx   float   Adaptive second moment  for u filter

uIyy   float   Adaptive second moment  for u filter

uIxy   float   Adaptive second moment  for u filter

fwhmA   float   Size of the object along major axis (pixels) 

fwhmB   float   Size of the object along minor axis (pixels) 

fwhmTheta  degrees  float   Position angle of the major axis w.r.t. Xaxis 

flux   float   Measured DIA flux for the source (ADUs) 

snr    float   SignaltoNoise ratio

ugColor   double   Precalculated color: difference between u and g) 

grColor   double   Precalculated color: difference between g and r) 

riColor   double   Precalculated color: difference between r and i) 

izColor   double   Precalculated color: difference between i and z) 

zyColor   double   Precalculated color: difference between z and y) 

moment0   float   Sum of all flux of all pixels that belong to a source  placeholder

moment1_x   float   Center of light  x component  placeholder

moment1_y   float   Center of light  y component  placeholder

moment2_xx   float   Standard deviation about center of light  xx component  placeholder

moment2_xy   float   Standard deviation about center of light  xy component  placeholder

moment2_yy   float   Standard deviation about center of light  yy component  placeholder

moment3_xxx   float   Skewness of the profile  xxx component  placeholder

moment3_xxy   float   Skewness of the profile  xxy component  placeholder

moment3_xyy   float   Skewness of the profile  xyy component  placeholder

moment3_yyy   float   Skewness of the profile  yyy component  placeholder

moment4_xxxx   float   Kurtosis  xxxx component  placeholder

moment4_xxxy   float   Kurtosis  xxxy component  placeholder

moment4_xxyy   float   Kurtosis  xxyy component  placeholder

moment4_xyyy   float   Kurtosis  xyyy component  placeholder

moment4_yyyy   float   Kurtosis  yyyy component  placeholder

splitPercentage  %  int8   percentage of the split  all for a given source must add up to 100%

redshift   float   Photometric redshift 

photoZ1   float   

photoZ2   float   

photoZ1Outlier   float   

photoZ2Outlier   float   

probability   int8   Probability that given object has photoz 

uAmplitude   float   amplitude of magnitude variations  for u filter

uPeriod   float   period of magnitude variations  for u filter

primaryPeriod   float   Average period across all filters 

uTimescale  days  float   timescale of flux variations  for u filter

uNumObs    int32   number of measurements in the lightcurve  for u filter

uVarProb  %  int16   probability of variability. 100% = variable object  for u filter

bias   float   Bias level for the calibrated image 

gain   float   Gain value for the amplifier 

rdNoise  electrons  float   Read noise value  for this particular element, eg AmpExposure

sky   float   The average sky level in the frame 

skySig   float   Sigma of distribution of sky values 

u_fringeTime   datetime   Time when corresponding CMFringeExposure was processed  for u filter

u_flatTime   datetime   Time when corresponding CMFlatExposure was processed  for u filter

Image pixel array properties     

binX   int16   binning in Xcoordinate 

binY   int16   binning in Ycoordinate 

sizeX   int16   Size of the image in Xdirection (along rows; binned pixels)  Ignores overscan but includes regions that may be considered outside of the data portion of the image

sizeY   int16   Size of the image in Ydirection (along columns; binned pixels)  Ignores overscan but includes regions that may be considered outside of the data portion of the image

averPixelValue   float   average pixel value 

stdevPixelValue   float   standard deviation of average pixel value 

Rectilinear coordinates     

row   double   Pixel coordinate (Y) of the source centroid 

col   double   Pixel coordinate (X) of the source centroid 

cx   double   xcomponent of the (RA,Dec) unit vector 

cy   double   ycomponent of the (RA,Dec) unit vector 

cz   double   zcomponent of the (RA,Dec) unit vector 

flags     

flag    [varies]   Flag to indicate a problem/special condition 

flag4association    int16   Flag to indicate a problem/special condition related to Association Pipeline 

flag4detection    int16   Flag to indicate a problem/special condition related to Detection Pipeline 

flag4wcs    int16   Flag to indicate a problem/special condition related to WCS 

isProvisional   bool   If this is set to true it indicates that the object was created at the base camp. If set to false, it means it was created by Deep Detection 

url    string   logical url of the corresponding FITS file 

imagePStampURL   string(255)   Logical URL describing where the image postamp associated with the alert is located 

templatePStampURL   string(255)   Logical URL of the postagestamp of the template image related to given alert 

alertURL   string(255)   Logical URL to the actual alert sent 

nCombine    int32   Number of images coadded to create a deeper image 

probability  %  int8   Probability that given object is of given type 

sizeRa   float   size of ra  this appears in postage stamp table

sizeDecl   float   size of decl  this appears in postage stamp table

mops related     

a   float   semimajor axis of the orbit (AU) 

incl  degrees  float   inclination of the orbit 

e   float   eccentricity of the orbit 

periTAI   float   TAI of the perihelion passage (comets) 

periDist   float   Perihelion distance (AU) 

omega   float   argument of perihelion 

node   float   longitude of the ascending node 

meanAnom   float   mean anomaly of the orbit 

qual   float   measure of the accuracy of the derived orbit, classification, etc.  can be more than one. Placeholder

various ids     

alertId    int32   Id of an Alert 

amplifierId    int16   Id of an Amplifier 

ccExposureId    int64   Id of CCD Exposure 

filterId    int8   Id of a Filter 

objectId    int64   Id of an Astronomical Object 

movingObjectId    int64   Id of a Moving Object 

visitId    int32   Id of a Visit 

flatExposureId    int32   Id of a Flat Exposure 

biasExposureId    int32   Id of a Bias Exposure 

darkExposureId    int32   Id of a Dark Exposure 

cmFlatExposureId    int32   Id of a Calibrated Master Flat Exposure 

subtractedExposureId    int32   Id of a Subtracted Exposure 

varianceExposureId    int32   Id of a Variance Exposure
