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:

min_val < ITEM_NAME < max_val
ITEM_NAME = value
ITEM_NAME = [value_1, value_2, value_3, ... value_10]
ITEM_NAME > value
ITEM_NAME < value
ITEM_NAME = value(tolerance) e.g. maj=12.0(5.0)
ITEM_NAME Selects entry if ITEM_NAME is non-zero

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:

ITEM	DESCRIPTION
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