Additional Constraints for FIRST Catalog Search

In the Additional Constraints field you can restrict the search using many different parameters from the catalog. For example, if you only want to select sources with peak flux densities brighter than 10 mJy, you can enter fpeak>10 in the field.

You can search the entire catalog (not just a section restricted by position) by deleting the RA and Dec values. Note that only 500 sources can be returned from a single search; if your search returns a significantly larger number you may be better off retrieving the complete catalog.

There are a variety of ways the constraints can be specified:

The less than sign (<) is interpreted as less than or equal and the greater than sign (>) is interpreted as greater than or equal. For a string parameter (the only one is fldname), ITEM_NAME = value matches if the string value occurs anywhere in the item.

You can include more than one constraint. Multiple constraints are separated by commas. For example, to select all the faint sources with sidelobe probabilities less than 0.2, use fpeak<10,sideprob<0.2.

The ITEM_NAME in the expressions above may be selected from among these parameters:

RA RA (J2000, degrees)
DEC DEC (J2000, degrees)
FPEAK peak flux density (mJy/beam)
FINT integrated flux density (mJy)
SIDEPROB sidelobe probability (larger means more likely sidelobe)
RMS rms at source position (mJy/beam)
MAJ deconvolved major axis FWHM of source (arcsec)
MIN deconvolved minor axis FWHM of source (arcsec)
PA deconvolved position angle of source (degrees)
FMAJ fitted major axis FWHM of source (arcsec)
FMIN fitted minor axis FWHM of source (arcsec)
FPA fitted position angle (degrees)
FISLAND integrated flux density of island (mJy)
FISLMAX peak flux density of island (mJy/beam)
ISLAND island number in field (brightest = 1)
SRCNUM source number in island
SRCTOT total number of sources fitted in island
FLDNAME name of field (char*16)
YEAR epoch of observation (years)
MJD epoch of observation (MJD)
MJDRMS rms for epoch (days)
NSDSS SDSS matches within 8" (-1 means not in DR6 area)
SDSSSEP Distance to closest SDSS match (99 = no match)
SDSSMAG i magnitude of closest SDSS match
SDSSCLASS SDSS classification ('s'=star, 'g'=galaxy, '-'=no match)
NTMASS 2MASS matches within 8"
TMASSSEP Distance to closest 2MASS match (99 = no match)
TMASSMAG K magnitude of closest 2MASS match