Common Vocabulary
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 table-specific meaning, for example in PhotoZ table it means probability that given object has a photo z.
| name | unit | type | ucd | description | comments |
| Position related | |||||
| 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 | |||
| WCS related | |||||
| 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 low-left corner | probably something more fancy needed | |
| decl_ll | degrees | double | Decl for the low-left corner | probably something more fancy needed | |
| ra_lr | degrees | double | Ra for the low-right corner | probably something more fancy needed | |
| decl_lr | degrees | double | Decl for the low-right corner | probably something more fancy needed | |
| ra_ul | degrees | double | Ra for the upper-left corner | probably something more fancy needed | |
| decl_ul | degrees | double | Decl for the upper-left corner | probably something more fancy needed | |
| ra_ur | degrees | double | Ra for the upper-right corner | probably something more fancy needed | |
| decl_ur | degrees | double | Decl for the upper-right corner | probably something more fancy needed | |
| Time related | |||||
| 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 beginning-of-first-exposure to end-of-last-exposure. | |||
| 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 end-of-last-exposure minus beginning-of-first-exposure. | |||
| 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 | |||
| Observation related | |||||
| zd | float | Zenith distance at observation mid-point | |||
| 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 alt-az 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 zero-point | |||
| PSF related | |||||
| 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 | Chi-square value for the PSF fit | |||
| Magnitudes and shapes | |||||
| 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. X-axis | ||
| flux | float | Measured DIA flux for the source (ADUs) | |||
| snr | - | float | Signal-to-Noise 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% | |
| Redshifts | |||||
| redshift | float | Photometric redshift | |||
| photoZ1 | float | ||||
| photoZ2 | float | ||||
| photoZ1Outlier | float | ||||
| photoZ2Outlier | float | ||||
| probability | int8 | Probability that given object has photo-z | |||
| Variability | |||||
| 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 | |
| Calibration related | |||||
| 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 X-coordinate | |||
| binY | int16 | binning in Y-coordinate | |||
| sizeX | int16 | Size of the image in X-direction (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 Y-direction (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 | x-component of the (RA,Dec) unit vector | |||
| cy | double | y-component of the (RA,Dec) unit vector | |||
| cz | double | z-component 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 | |||
| uncategorized | |||||
| 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 co-added 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 | semi-major 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 |
