Child pages
  • Summary Table Column Descriptions
Skip to end of metadata
Go to start of metadata

A product of the Operations Simulator (OpSim) is an SQLite database file, named using its unique identifier (hostname_sessionID), which contains all the information pertaining to that simulated survey. This database file includes an extra table created to facilitate analysis with MAF which is named "Summary".  "Summary" contains the most commonly used fields from the output tables, and additional useful quantities such as the limiting magnitude and a set of dithered coordinates.

This is a description of the columns in the "Summary" table.

**Please Note**, a single OpSim visit can sometimes be used by multiple proposals.  Thus, there are entries in the Summary table that are identical except for the value of propID.  When searching the database, one will usually want to use a "group by" clause.  For example:

Using "group by"
sqlite> select count(fieldRA) from (select fieldRA from summary where night = 1 and filter = 'r' group by expMJD);
sqlite> select count(fieldRA) from (select fieldRA from summary where night = 1 and filter = 'r');

Without "group by", we get three repeated entries. If you use the MAF framework, the "group by" is done automatically.

Also note, we are using the LSST nomenclature, and each record in the database describes a "visit", where a visit is a pair of exposures. 

Column NameTypeUnitsDescription
obsHistIDinteger-Unique visit identifier (same as ObsHistory.obsHistID).
sessionIDinteger-Session identifier which is unique for simulated surveys created on a particular machine or hostname. Simulated surveys are uniquely named using the form hostname_sessionID.
propIDinteger-Unique (for every run) identifier for every proposal (observing mode) specified in a simulated survey. Note that a single visit can satisfy multiple proposals, and so duplicate rows (except for the propID) can exist in the Summary table (same as Proposal.propID).
fieldIDinteger-Unique field (or target on the sky) identifier (same as Field.fieldID). OpSim uses a set of 5292 fields (targets) obtained from a fixed tessellation of the sky.
fieldRArealradiansRight Ascension (J2000) of the field center for this visit (same as Field.fieldRA).
fieldDecrealradiansDeclination (J2000) of the field center for this visit (same as Field.fieldDec).
filtertext-Filter used during the visit; one of u, g, r, i, z, or y.

Time of the visit relative to 0 sec at the start of a simulated survey.

expMJDrealdaysModified Julian Date at the start of a visit.
nightintegernoneThe integer number of nights since the start (expDate = 0 sec) of the survey. The first night is night = 0.
visitTimerealsecondsCurrently, a visit comprises two 15- second exposures and each exposure needs 1 sec for the shutter action and 2 sec for the CCD readout. The second readout is assumed to occur while moving to the next field (see slewTime), so the length of each visit for the WFD observing mode is 34 sec.
visitExpTimerealsecondsTotal integration time on the sky during a visit, which for current observing modes is 30 sec (see visitTime).
finRankreal-Target rank among all proposals including all priorities and penalties (generally used for diagnostic purposes).
finSeeingrealarcseconds**Depriciated column** The FWHM of the seeing including wavelength dependent atmospheric and optical contributions (derived from rawSeeing).
FWHMgeomrealarcseconds"Geometrical" full-width at half maximum. The actual width at half the maximum brightness. Use FWHMgeom to represent the FWHM of a double-gaussian representing the physical width of a PSF.
FWHMeffrealarcseconds"Effective" full-width at half maximum, typically ~15% larger than FWHMgeom. Use FWHMeff to calculate SNR for point sources, using FWHMeff as the FWHM of a single gaussian describing the PSF.
transparencyreal-The value (in 8ths) from the Cloud table closest in time to this visit.
airmassreal-Airmass at the field center of the visit.
vSkyBrightrealmag/arcsec2The sky brightness in the Johnson V band calculated from a Krisciunas and Schaeffer model with a few modifications. This model uses the Moon phase, angular distance between the field and the Moon and the field’s airmass to calculate added brightness to the zero-Moon, zenith sky brightness (e.g. Krisciunas 1997, PASP, 209, 1181; Krisciunas and Schaefer 1991, PASP, 103, 1033; Benn and Ellison 1998, La Palma Technical Note 115).
filtSkyBrightnessrealmag/arcsec2Measurements of the color of the sky as a function of lunar phase are used to correct vSkyBright to the sky brightness in the filter used during this visit.

The orientation of the sky in the focal plane measured as the angle between North on the sky and the "up" direction in the focal plane. XXX-We need to document the sense of this–is it to the east or west.


The physical angle of the rotator with respect to the mount.

rotSkyPos = rotTelPos - ParallacticAngle

lstrealhoursLocal SiderealTime at the start of the visit (0 - 24 hours).
altituderealradiansAltitude of the field center at the start of the visit.
azimuthrealradiansAzimuth of the field center at the start of the visit.
dist2MoonrealradiansDistance from the field center to the moon's center on the sky.
solarElongrealdegreesSolar elongation or the angular distance between the field center and the sun (0 - 180 deg).
moonRArealradiansRight Ascension of the Moon.
moonDecrealradiansDeclination of the Moon.
moonAltrealradiansAltitude of the Moon taking into account the elevation of the site.
moonAZrealradiansAzimuth of the Moon
moonPhasereal%Percent illumination of the Moon (0=new, 100=full)
sunAltrealradiansAltitude of the Sun taking into account the elevation of the site, but with no correction for atmospheric refraction.
sunAzrealradiansAzimuth of the Sun with no correction for atmospheric refraction.
phaseAnglereal*Intermediate values in the calculation of vSkyBright using the Krisciunas and Schaeffer models.
rScatterreal*" "
mieScatterreal*" "
moonBrightreal*" "
darkBrightreal*" "

The seeing as taken from the Seeing table which is an ideal seeing at zenith and at 500 nm.

windreal-A placeholder for real telemetry.
humidityreal-A placeholder for real telemetry.

Distance on the sky between the target field center and the field center of the previous visit.


The time between the end of the second exposure in the previous visit and the beginning of the first exposure in the current visit.

fiveSigmaDepthrealmagnitudesThe magnitude of a point source that would be a 5 sigma detection (see Z. Ivezic et al,

The offset from the Right Ascension of the field center representing a "hex-dithered" pattern.

ditheredDecrealradiansThe offset from the Declination of the field center representing a "hex-dithered" pattern.
  • No labels