J/ApJS/172/583 NEP source catalog (Hwang+, 2007)
An optical source catalog of the North Ecliptic Pole region.
Hwang N., Lee M.G., Lee H.M., Im M., Kim T., Matsuhara H., Wada T.,
Oyabu S., Pak S., Chun M.-Y., Watarai H., Nakagawa T., Pearson C.,
Takagi T., Hanami H., White G.J.
<Astrophys. J. Suppl. Ser., 172, 583-598 (2007)>
=2007ApJS..172..583H 2007ApJS..172..583H (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, ugriz ; Galaxies, optical ; Clusters, galaxy
Keywords: catalogs - galaxies: clusters: general - galaxies: general -
galaxies: photometry
Abstract:
We present a five-band (u* g' r' i' z') optical photometry catalog
of the sources in the North Ecliptic Pole (NEP) region based on deep
observations made with MegaCam at CFHT. The source catalog covers
about 2 square degree area centered at the NEP and reaches depths of
about 26mag for u*, g', r' bands, about 25mag for i' band, and about
24mag for z' band (4σ detection over a 1" aperture). The total
number of cataloged sources brighter than r'=23mag is about 56000
including both point sources and extended sources.
From the investigation of photometric properties using the color-
magnitude diagrams and color-color diagrams, we have found that the
colors of extended sources are mostly (u*-r')<3.0 and (g'-z')>0.5.
This can be used to separate the extended sources from the point
sources reliably, even for the faint source domain where typical
morphological classification schemes hardly work efficiently. We
have derived an empirical color-redshift relation of the red sequence
galaxies using the Sloan Digital Sky Survey data. By applying this
relation to our photometry catalog and searching for any spatial
overdensities, we have found two galaxy clusters and one nearby galaxy
group.
Description:
The observation of the north ecliptic pole (NEP) region was carried
out over nine photometric nights between 2004 August 22 and September
22 using the 3.6m CFHT telescope located at Mauna Kea, Hawaii.
The u* g' r' i' z' filter system provided with MegaCam is basically
the same as that used by the Sloan Digital Sky Survey (SDSS; York et
al. 2000AJ....120.1579Y 2000AJ....120.1579Y) except for the u* filter.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 145 56623 NEP Optical Source Catalog
--------------------------------------------------------------------------------
See also:
J/ApJS/123/377 : u*g*r*i*z* Photometry of stars, galaxies, QSOs (Newberg+ 1999)
J/ApJS/162/304 : ROSAT NEP X-ray source catalog (Henry+, 2006)
J/PASJ/59/S529 : NEP deep survey at 11um (Lee+, 2007)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- [HLL2007] Source ID number
8- 18 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000) (1)
20- 29 F10.7 deg DEdeg Declination in decimal degrees (J2000) (1)
31- 36 F6.3 mag umag ?=99.000 The u* band AB magnitude (2)
38- 43 F6.3 mag e_umag ?=99.000 The error on umag
45- 50 F6.3 mag gmag ?=99.000 The g' band AB magnitude (2)
52- 57 F6.3 mag e_gmag ?=99.000 The error on gmag (2)
59- 64 F6.3 mag rmag The r' band AB magnitude (2)
66- 70 F5.3 mag e_rmag The error on rmag (2)
72- 77 F6.3 mag imag ?=99.000 The i' band AB magnitude (2)
79- 84 F6.3 mag e_imag ?=99.000 The error on imag (2)
86- 91 F6.3 mag zmag ?=99.000 The z' band AB magnitude (2)
93- 99 F7.3 mag e_zmag ?=99.000 The error on zmag (2)
101-102 I2 --- Flag Sextractor source extraction flag (3)
104-107 F4.2 --- S/G [0/1] Stellarity - star/galaxy classifier (4)
109-113 F5.3 --- Ell [0/1] Ellipticity, from SExtractor
115-120 F6.3 arcsec FWHM Full-Width at Half-Maximum (6)
122-127 F6.3 arcsec Reff Effective radius or half-light radius (7)
129-134 F6.3 arcsec MajAxis Semi-major axis length
136-143 F8.3 arcsec2 Area Isophotal detection area
145 I1 --- Field [1/2] Field number: 1=NEP-E, 2=NEP-W
--------------------------------------------------------------------------------
Note (1): The uncertainties of the astrometric solution derived by Elixir
are about ± 0.5 arcseconds.
Note (2): These are given by MAG_AUTO and MAGERR_AUTO parameters of
SExtractor, which are Kron-like elliptical aperture magnitudes and
their errors. Values of "99.000" indicate NULL values.
Note (3): The extraction flag of a source given as a sum of powers of 2 by
SExtractor. If a source has neighbors (flag = 1) and is blended with
another source (flag = 2) and some pixels are saturated (flag = 4),
then the final extraction flag given to the source is 7 (= 1 + 4 + 2).
Generally, a source with the extraction flag 0 gives the most reliable
photometry. For detailed information on this flag, see the SExtractor
User's Manual.
Note (4): Calculated from a g',r',i',z' combined detection image. This
index has a value between 1 (point sources) and 0 (extended sources).
See Figure 2 for the distribution of this index.
Note (6): Calculated under the assumption that the source has a Gaussian
profile
Note (7): This value is computed by setting the input parameter
PHOT_FLUXFRAC=0.5 and is given by the output parameter FLUX_RADIUS.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-May-2009