Third Release of DENIS (Deep Near-Infrared Survey of the Southern Sky)

This data release, from 2005 September, consists of 355,220,325 point sources detected by DENIS. The release contains 3662 strips, each of which is 30 degrees long in Declination and 12 arcmin wide in Right Ascension (with an overlap of 2 arcminutes between consecutive strips), and covers approximately 16,700 square degrees of the southern sky. The northernmost declination covered is ~+02d07m and the southernmost is ~-87d37m. Multiple detections of single point sources have been merged in image overlaps within individual strips, but sources can have multiple detections in overlapping strips. DENIS observations began at the end of 1995 and were completed on 09 September 2001.

The survey was conducted simultaneously in three bands: one optical band (Gunn-i at 0.82um, hereafter referred to as "I") and two near-infrared bands (J at 1.25um and Ks at 2.15um), with limiting magnitudes of 18.5 mag, 16.5 mag, and 14.0 mag and saturation magnitudes of 9.8 mag, 7.5 mag, and 6 mag at I, J, and Ks, respectively. Documentation at CDS states that the astrometric accuracy of a typical point source is better than 1 arcsec and photometric accuracy is better than 0.1 mag, although the range of SNR over which these apply is not specified. DENIS was conducted by a European consortium using the 1m telescope at the European Southern Observatory in La Silla, Chile.

The following table contains brief descriptions of the parameters provided for each source in the DENIS 3rd Release. The columns are:

Column Name: Name of the parameter.

Format: The ascii-equivalent format of the field, expressed in "C" readable notation. This is useful when parsing the aligned tabular output from IRSA/GATOR. Although the data values will conform to these formats, the actual width of the field in the GATOR output may be padded with extra blank spaces to accommodate column headers. Note that some fields contain null values that will require special handling when parsing tables drawn from IRSA/GATOR.

Units: The units of the parameter. A value of "---" in this column means that the parameter is dimensionless or non-numeric.

Nulls: A "yes" in this column means that this parameter can be null. A "no" means that there will always be a value in this column.

Description: A brief description of the parameter and its values.

Column Name Format Units Nulls Description

denisid %16s --- no DENIS designation formed from the sexagesimal, equatorial position of the source: hhmmss.s+ddmmss. The naming convention takes the form "DENIS Jhhmmss.s+ddmmss", where "J" indicates the position is J2000. Please note that catalog entries omit the prefix "DENIS" to conserve space.

image %7i --- no DENIS image number containing the source. The image number is incremented at each image taken during the survey. Each DENIS strip contains 180 images that are 12x12 arcminutes square. For a source resulting from the merging of two consecutive overlapping images (N and N+1) in the same strip (mult=1, below), the image number corresponds to the first image, N.

strip %4i --- no DENIS strip number containing the source.

ra %10.6f deg no J2000 Right Ascension, in decimal degrees, of the source as measured by DENIS.

dec %10.6f deg no J2000 Declination, in decimal degrees, of the source as measured by DENIS.

ipsf, jpsf, kpsf %6.3f mag yes PSF-fit magnitude at each of the three DENIS bands (I, J, Ks).

e_ipsf, e_jpsf, e_kpsf %5.2f mag yes Error in the PSF-fit magnitude at each of the three DENIS bands (I, J, Ks).

iap##, jap##, kap## %6.3f mag yes Aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size
5.5 arcsec if ##=55
4.5 arcsec if ##=45
3.5 arcsec if ##=35

e_iap##, e_jap##, e_kap## %5.2f mag yes Error in the aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size
5.5 arcsec if ##=55
4.5 arcsec if ##=45
3.5 arcsec if ##=35

iap##c, jap##c, kap##c %6.3f mag yes Corrected, aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size
3.5 arcsec if ##=35
2.5 arcsec if ##=25
1.5 arcsec if ##=15

e_iap##c, e_jap##c, e_kap##c %5.2f mag yes Error in the corrected, aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size
3.5 arcsec if ##=35
2.5 arcsec if ##=25
1.5 arcsec if ##=15

rmag %4.1f mag yes R-band magnitude reported for the nearest match in the USNO-A2.0 catalog.

bmag %4.1f mag yes B-band magnitude reported for the nearest match in the USNO-A2.0 catalog.

iqual, jqual, kqual %3i --- yes Quality flag at each of the three DENIS bands (I, J, Ks). Values run from 0 (poorest quality) to 100 (perfect).

icorr, jcorr, kcorr %3i --- yes Correlation (goodness of fit) to the point spread function (PSF) at each of the three DENIS bands (I, J, Ks). Values are normalized to run from 0 (poorest match to the PSF) to 100 (pure point-source PSF). Cosmic rays and extended sources will have low values.

imcor, jmcor, kmcor %4.2f --- yes Mean correlation to PSF at each of the three DENIS bands (I, J, Ks). Values run from 0 to 1.

ixpos, iypos %5.1f pix yes X-axis and Y-axis pixel position of source at I-band.

jxpos, jypos %5.1f pix yes X-axis and Y-axis pixel position of source at J-band.

kxpos, kypos %5.1f pix yes X-axis and Y-axis pixel position of source at Ks-band.

ra_usno %10.6f deg yes J2000 Right Ascension, in decimal degrees, of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.

dec_usno %10.6f deg yes J2000 Declination, in decimal degrees, of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.

ep_usno %8.3f year yes Epoch of USNO-A2.0 observation of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.

d_usno %3i mas yes Distance, in units of milli-arcseconds, to the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.

obsjd %14.6f day no Julian Date of the DENIS observation.

iflg, jflg, kflg %4s --- yes Image and source quality flag for each of the three DENIS bands. This flag is a concatenation of the image and source flags, in hexadecimal format.
The first two digits (the image flag) contain:
Bit 0 (0100) = clouds during observation
Bit 1 (0200) = electronic read-out problem
Bit 2 (0400) = internal temperature problem
Bit 3 (0800) = very bright star
Bit 4 (1000) = bright star
Bit 5 (2000) = stray light
Bit 6 (4000) = unknown problem

The last two digits (the source flag) contain:
Bit 0 (0001) = source might be dust on mirror
Bit 1 (0002) = source is a ghost detection of a bright star
Bit 2 (0004) = source is saturated
Bit 3 (0008) = source is multiple detection
Bit 4 (0010) = reserved

For example, a source with iflg="080c" should be interpreted as follows: The I-band image flag ("08") indicates a very bright star, and the I-band source flag ("0c", which equals 4+8 in hexadecimal) indicates two conditions: source is saturated and source is a multiple detection.
Sources with flags of "0000" are those in which no image or source problems were found.

mult %1i --- no Multiplicity flag. If set to 1, this flag indicates that the source was detected in two consecutive images and that the two measurements have been combined. Singly observed sources will have mult=0.

Column Name	Format	Units	Nulls	Description
denisid	%16s	---	no	DENIS designation formed from the sexagesimal, equatorial position of the source: hhmmss.s+ddmmss. The naming convention takes the form "DENIS Jhhmmss.s+ddmmss", where "J" indicates the position is J2000. Please note that catalog entries omit the prefix "DENIS" to conserve space.
image	%7i	---	no	DENIS image number containing the source. The image number is incremented at each image taken during the survey. Each DENIS strip contains 180 images that are 12x12 arcminutes square. For a source resulting from the merging of two consecutive overlapping images (N and N+1) in the same strip (mult=1, below), the image number corresponds to the first image, N.
strip	%4i	---	no	DENIS strip number containing the source.
ra	%10.6f	deg	no	J2000 Right Ascension, in decimal degrees, of the source as measured by DENIS.
dec	%10.6f	deg	no	J2000 Declination, in decimal degrees, of the source as measured by DENIS.
ipsf, jpsf, kpsf	%6.3f	mag	yes	PSF-fit magnitude at each of the three DENIS bands (I, J, Ks).
e_ipsf, e_jpsf, e_kpsf	%5.2f	mag	yes	Error in the PSF-fit magnitude at each of the three DENIS bands (I, J, Ks).
iap##, jap##, kap##	%6.3f	mag	yes	Aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size 5.5 arcsec if ##=55 4.5 arcsec if ##=45 3.5 arcsec if ##=35
e_iap##, e_jap##, e_kap##	%5.2f	mag	yes	Error in the aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size 5.5 arcsec if ##=55 4.5 arcsec if ##=45 3.5 arcsec if ##=35
iap##c, jap##c, kap##c	%6.3f	mag	yes	Corrected, aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size 3.5 arcsec if ##=35 2.5 arcsec if ##=25 1.5 arcsec if ##=15
e_iap##c, e_jap##c, e_kap##c	%5.2f	mag	yes	Error in the corrected, aperture-measured magnitude at each of the three DENIS bands (I, J, Ks) using an aperture of size 3.5 arcsec if ##=35 2.5 arcsec if ##=25 1.5 arcsec if ##=15
rmag	%4.1f	mag	yes	R-band magnitude reported for the nearest match in the USNO-A2.0 catalog.
bmag	%4.1f	mag	yes	B-band magnitude reported for the nearest match in the USNO-A2.0 catalog.
iqual, jqual, kqual	%3i	---	yes	Quality flag at each of the three DENIS bands (I, J, Ks). Values run from 0 (poorest quality) to 100 (perfect).
icorr, jcorr, kcorr	%3i	---	yes	Correlation (goodness of fit) to the point spread function (PSF) at each of the three DENIS bands (I, J, Ks). Values are normalized to run from 0 (poorest match to the PSF) to 100 (pure point-source PSF). Cosmic rays and extended sources will have low values.
imcor, jmcor, kmcor	%4.2f	---	yes	Mean correlation to PSF at each of the three DENIS bands (I, J, Ks). Values run from 0 to 1.
ixpos, iypos	%5.1f	pix	yes	X-axis and Y-axis pixel position of source at I-band.
jxpos, jypos	%5.1f	pix	yes	X-axis and Y-axis pixel position of source at J-band.
kxpos, kypos	%5.1f	pix	yes	X-axis and Y-axis pixel position of source at Ks-band.
ra_usno	%10.6f	deg	yes	J2000 Right Ascension, in decimal degrees, of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.
dec_usno	%10.6f	deg	yes	J2000 Declination, in decimal degrees, of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.
ep_usno	%8.3f	year	yes	Epoch of USNO-A2.0 observation of the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.
d_usno	%3i	mas	yes	Distance, in units of milli-arcseconds, to the nearest match (within 2 arcsec) in the USNO-A2.0 catalog.
obsjd	%14.6f	day	no	Julian Date of the DENIS observation.
iflg, jflg, kflg	%4s	---	yes	Image and source quality flag for each of the three DENIS bands. This flag is a concatenation of the image and source flags, in hexadecimal format. The first two digits (the image flag) contain: Bit 0 (0100) = clouds during observation Bit 1 (0200) = electronic read-out problem Bit 2 (0400) = internal temperature problem Bit 3 (0800) = very bright star Bit 4 (1000) = bright star Bit 5 (2000) = stray light Bit 6 (4000) = unknown problem The last two digits (the source flag) contain: Bit 0 (0001) = source might be dust on mirror Bit 1 (0002) = source is a ghost detection of a bright star Bit 2 (0004) = source is saturated Bit 3 (0008) = source is multiple detection Bit 4 (0010) = reserved For example, a source with iflg="080c" should be interpreted as follows: The I-band image flag ("08") indicates a very bright star, and the I-band source flag ("0c", which equals 4+8 in hexadecimal) indicates two conditions: source is saturated and source is a multiple detection. Sources with flags of "0000" are those in which no image or source problems were found.
mult	%1i	---	no	Multiplicity flag. If set to 1, this flag indicates that the source was detected in two consecutive images and that the two measurements have been combined. Singly observed sources will have mult=0.

[Last Updated: 2008 February 29, by J. Davy Kirkpatrick]