Table information for 'ztf.reference'

General

Table Description:

Metadata for the ZTF reference images used in difference imaging, including the photometric properties of the nearest source in the reference image and the temporal extent of the reference image stack.

This table is available for ADQL queries and through the TAP endpoint.

Resource Description:

Legacy ZTF astronomical catalog containing objects, detections, photometric measurements, classifications, and cross-matches from the Zwicky Transient Facility (ZTF) survey, as processed by the ALeRCE broker pipeline.

For a list of all services and tables belonging to this table's resource, see Information on resource 'ALeRCE ZTF Legacy Catalog'

Citing this table

To cite the table as such, we suggest the following BibTeX entry:

@MISC{vo:ztf_reference,
  year=2026,
  title={{ZTF} Reference Images},
  author={{ALeRCE} Team},
  url={http://tap.alerce.online/tableinfo/ztf.reference},
  howpublished={{VO} resource provided by the {ALeRCE} {TAP} service}
}

Columns

Sorted alphabetically. [Sort by DB column index]

NameTable Head DescriptionUnitUCD
candid Candid Candidate identifier associated with this reference N/A meta.id
chinr Chinr Chi value of nearest source match in reference image N/A stat.fit.chi2
decnr Decnr Declination of nearest source in reference image deg pos.eq.dec
fid Fid Filter identifier N/A meta.id;instr.filter
field Field ZTF field identifier N/A obs.field
magnr Magnr Magnitude of nearest source in reference image mag phot.mag
mjdendref Mjdendref MJD of end of reference image stack d time.end
mjdstartref Mjdstartref MJD of start of reference image stack d time.start
nframesref Nframesref Number of frames co-added in reference image stack N/A meta.number;obs
oid Oid ZTF object identifier N/A meta.id;src
ranr Ranr Right ascension of nearest source in reference image deg pos.eq.ra
rcid Rcid Readout channel identifier N/A meta.id;instr.det
rfid Rfid Reference image field identifier N/A meta.id
sharpnr Sharpnr Sharpness of nearest source in reference image N/A src.morph.param
sigmagnr Sigmagnr Uncertainty in magnitude of nearest source in reference image mag stat.error;phot.mag

Columns that are parts of indices are marked like this.

VOResource

VO nerds may sometimes need VOResource XML for this table.