SVO Calar Alto CAFOS Direct Imaging First Data Release archive

Detection catalogue.

Grant PID2020-112494GBI00 funded by
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Web access

The archive system implements a very simple search interface that permits queries by coordinates/radius and or range (*) of magnitudes. The default search radius is set to 5 arcsec. The user can also select the maximum number of sources to return (with values ranging from 10 to unlimited).

The result of the query is a HTML table with all the sources found in the archive fulfilling the search criteria. Detailed information on the output fields can be obtained placing the mouse over the question mark ("?") located close to the name of the column. Results can be sorted by just clicking on the name of the column. The archive implements the SAMP (Simple Application Messaging Protocol). SAMP allows applications to communicate with each other in a seamless and transparent way for the user. This way, the results of a query can be easily transferred to other VO applications by just clicking the "Send table to VO Apps" button.

(*) When a range is specified in a search the user must give both a minimum and maximum value for the corresponding quantity. If only a minimum value is given, all results with values larger than that will be obtained. If only a maximum value is given, all results with values smaller than that will be obtained.

Virtual Observatory access

The Virtual Observatory (VO) is an international initiative whose primary goal is to provide an efficient access and analysis of the information hosted in astronomical archives and services. Having a VO-compliant archive is an important added value for an astronomical project to guarantee the optimum scientific exploitation of their datasets.

Our archive system has been designed following the IVOA standards and requirements. In particular, it implements the Cone Search protocol, a standard defined for retrieving records from a catalogue of astronomical sources. The query made through the Cone Search service describes a sky position and an angular distance, defining a cone on the sky. The response returns a list of astronomical sources from the catalogue whose positions lie within the cone, formatted as a VOTable.

Frequently Asked Questions

How to make a query by magnitudes?

Parameters contained in the detection catalogue

Parameter Units Description
RA (J2000)degCelestial Right Ascension (J2000)
e_RA (J2000)arcsecRight ascension error
DEC (J2000)degCelestial Declination (J2000)
e_DEC (J2000)arcsecDeclination error
SourceNID-Numerical ID of sources detected more than once within 0.5 arcsec
detectionID-Detection identifier
Image-Image identifier
Image_url-URL to access the reduced image
gmagmagPSF calibrated magnitude in the g band
e_gmagmagPSF calibrated magnitude error in the g band
rmagmagPSF calibrated magnitude in the r band
e_rmagmagPSF calibrated magnitude error in the r band
imagmagPSF calibrated magnitude in the i band
e_imagmagPSF calibrated magnitude error in the i band
zmagmagPSF calibrated magnitude in the z band
e_zmagmagPSF calibrated magnitude error in the z band
Flag_phot-Calibration flag. "A" stands for calibrated magnitudes within the interval of magnitudes used for the photometric calibration, "B" for calibrated magnitudes fainter than the faintest magnitudes, and "C" for calibrated magnitudes brighter magnitudes than the brightest magnitude used for the photometric calibration.
Filter-Filter of observation
Ref_Cat-Reference catalogue used for the photometric calibration
Elongation-Elongation of the detection
Ellipticity-Ellipticity of the detection
FWHMarcsecFull width half maximum of the detection
SNR_WIN-Signal to noise ratio
SPREAD_MODEL-Spread parameter from model-fitting. It takes values close to zero for point sources, positive for extended sources (galaxies), and negative for detections smaller than the PSF, such as cosmic ray hits.
MJD-Modified Julian Date
DATE-OBSiso-8601Observing epoch
SourceSize-Number of detections for each source in GroupID
Notes-Notes on detections. "v" stands for the variable candidates, "TOI" identifies the targets of interest, "M" identifies the M candidates, "d" stands for M candidates within 500 pc, "u" stands for ultracool dwarf candidates, and "c" stands for M candidates that satisfy the three colour criteria applied.
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