Table information for 'alerce_tap.ztf_reference'

General

Table Description:

Information about ZTF reference (template) images used for difference imaging, including properties of the nearest catalog source, temporal coverage of the reference image stack, and field/CCD identifiers.

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

Resource Description:

Multi-survey astronomical object catalog containing astrometric and statistical information from multiple surveys. This table provides aggregated properties for astronomical objects including position, detection statistics, and temporal coverage.

For a list of all services and tables belonging to this table's resource, see Information on resource 'ALeRCE Multi-Survey Object Catalog'

Citing this table

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

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

Columns

Sorted by DB column index. [Sort alphabetically]

NameTable Head DescriptionUnitUCD
oid Oid Unique identifier for this object N/A meta.id;src
rfid Rfid Processing ID for reference image to facilitate archive retrieval N/A meta.id
measurement_id Measurement_id Unique identifier for the first detection associated with this reference image N/A meta.id
band Band Filter ID: 1=g, 2=r, 3=i N/A instr.bandpass
rcid Rcid Readout channel ID [00 .. 63] N/A instr.det
field Field ZTF field ID N/A obs.field
magnr Magnr Magnitude of nearest source in reference image PSF-catalog within 30 arcsec mag phot.mag
sigmagnr Sigmagnr 1-sigma uncertainty in magnr within 30 arcsec mag stat.error;phot.mag
chinr Chinr DAOPhot chi parameter of nearest source in reference image PSF-catalog within 30 arcsec N/A stat.fit.chi2
sharpnr Sharpnr DAOPhot sharp parameter of nearest source in reference image PSF-catalog within 30 arcsec (values between -0.13 and 0.1 indicate unresolved sources) N/A stat.value
ranr Ranr Right ascension of nearest source in reference image PSF-catalog, J2000 deg pos.eq.ra;meta.main
decnr Decnr Declination of nearest source in reference image PSF-catalog, J2000 deg pos.eq.dec;meta.main
mjdstartref Mjdstartref Observation Modified Julian Date of earliest exposure used to generate reference image d time.start
mjdendref Mjdendref Observation Modified Julian Date of latest exposure used to generate reference image d time.end
nframesref Nframesref Number of frames (epochal images) used to generate reference image N/A meta.number
created_date Created_date Date record was created N/A time.creation

Columns that are parts of indices are marked like this.

VOResource

VO nerds may sometimes need VOResource XML for this table.