This table contains proper motion information for the SWEEPS field. The proper motion is determined by a median fit to the source positions given in table AstromSourcePositions as a function of time for right ascension and declination independently and Galactic latitude and longitude independently. The fit is performed using the medfit algorithm in Numerical Recipes (Press et al. 1993). For right ascension (RA) in degrees, the fit for an object has the form
RA(t) = raMean + 3.6x10^6*pmRA/cos(Dec)*(t-epochMean)/365.25,
where t is the time expressed as an MJD, epochMean is the mean MJD of the object detections, raMean is the RA at the mean epoch, and pmRA is the RA proper motion in mas/yr. The first step in the medfit algorithm involves a least squares fit. The RA standard errors (1 sigma) of the least squares fit for the position at the mean epoch and the proper motion are designated by raMeanErr and pmRAErr, respectively. They are obtained using equations 34 and 35 of MathWorld. For a given object, medfit minimizes the mean absolute deviation of the RA data values from the fit. These RA directed distance value are given by dRA in table AstromSourcePositions. The mean absolute deviation of the RA data from the fit is designated by pmRADev. Similar fits are made for declination and Galactic longitude and latitude. See the HSC API web page for information on submitting GET requests.
Last update: July 19, 2019
| Column Name | Units | Data Type | Description |
|---|---|---|---|
| ObjID | none | bigint | identifier for the object. It corresponds to one or more matches in HSC v3. The mapping between ObjID and MatchID in HSC version 3 is available in table AstromSourcePositions. |
| NumSources | none | bigint | number of white light source detections for the ObjID |
| raMean | degrees | float | right ascension of the object at the mean epoch |
| decMean | degrees | float | declination of the object at the mean epoch |
| lonMean | degrees | float | Galactic longitude of the object at the mean epoch |
| latMean | degrees | float | Galactic latitude of the object at the mean epoch |
| raMeanErr | mas | float | error in right ascension at the mean epoch |
| decMeanErr | mas | float | error in declination at the mean epoch |
| lonMeanErr | mas | float | error in Galactic longitude at the mean epoch |
| latMeanErr | mas | float | error in Galactic latitude at the mean epoch |
| pmRA | mas/yr | float | right ascension proper motion |
| pmDec | mas/yr | float | declination proper motion |
| pmLon | mas/yr | float | Galactic longitude proper motion |
| pmLat | mas/yr | float | Galactic latitude proper motion |
| pmRAErr | mas/yr | float | right ascension proper motion error |
| pmDecErr | mas/yr | float | declination proper motion error |
| pmLonErr | mas/yr | float | Galactic longitude proper motion error |
| pmLatErr | mas/yr | float | Galactic latitude proper motion error |
| pmRADev | mas | float | mean absolute deviation of right ascension data from the proper motion fit |
| pmDecDev | mas | float | mean absolute deviation of declination data from the proper motion fit |
| pmLonDev | mas | float | mean absolute deviation of Galactic longitude data from the proper motion fit |
| pmLatDev | mas | float | mean absolute deviation of Galactic latitude data from the proper motion fit |
| epochStart | MJD | float | epoch of the earliest detection of the object |
| epochEnd | MJD | float | epoch of the latest detection of the object |
| epochMean | MJD | float | mean epoch of the detections of the object |
| Column Name | Units | Data Type | Description |