II/295 Spitzer IRAC survey of the galactic center (Ramirez+, 2008)
Point sources from a Spitzer IRAC survey of the galactic center.
Ramirez S.V., Arendt R.G., Sellgren K., Stolovy S.R., Cotera A.,
Smith H.A., Yusef-Zadeh F.
<Astrophys. J. Suppl. Ser., 175, 147-164 (2008)>
=2008ApJS..175..147R 2008ApJS..175..147R
ADC_Keywords: Cross identifications ; Surveys ; Photometry, infrared
Mission_Name: Spitzer
Keywords: Galaxy: center - stars: late-type
Abstract:
We have obtained Spitzer IRAC observations of the central
2.0°x1.4° (∼280x200pc) of the Galaxy at 3.6-8.0um. A
point-source catalog of 1065565 objects is presented. The catalog
includes magnitudes for the point sources at 3.6, 4.5, 5.8, and 8.0um,
as well as JHKs photometry from Two Micron All Sky Survey (2MASS). The
point-source catalog is confusion limited with average limits of 12.4,
12.1, 11.7, and 11.2mag for [3.6], [4.5], [5.8], and [8.0],
respectively. We find that the confusion limits are spatially variable
because of stellar surface density, background surface brightness
level, and extinction variations across the survey region. The overall
distribution of point-source density with Galactic latitude and
longitude is essentially constant, but structure does appear when
sources of different magnitude ranges are selected. Bright stars show
a steep decreasing gradient with Galactic latitude and a slow
decreasing gradient with Galactic longitude, with a peak at the
position of the Galactic center. From IRAC color-magnitude and
color-color diagrams, we conclude that most of the point sources in
our catalog have IRAC magnitudes and colors characteristic of red
giant and asymptotic giant branch (AGB) stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 106 735020 Galactic Center IRAC 1 (3.6um) source lists
table3.dat 106 700923 Galactic Center IRAC 2 (4.5um) source lists
table4.dat 106 493207 Galactic Center IRAC 3 (5.8um) source lists
table5.dat 106 323512 Galactic Center IRAC 4 (8.0um) source lists
table6.dat 108 207 Galactic Center IRAC sub-array photometry
table7.dat 340 1065565 Galactic Center 2MASS/IRAC Catalog
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/293 : GLIMPSE Source Catalog (I+II+3D) (IPAC 2008)
J/A+AS/97/587 : JHK photometry of Galactic center stars (Ruelas-Mayorga+ 1993)
Byte-by-byte Description of file: table[2-5].dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- --- [GC-IRAC-]
8 I1 --- Ch [1/4] Channel number:
1=3.6um, 2=4.5um, 3=5.8um, 4=8.0um
9 A1 --- --- [-]
10- 15 I06 --- ID Source identification number (1)
17 I1 --- --- Channnel number (repetition of Ch)
19- 20 I2 h RAh Hour of Right Ascension (J2000)
22- 23 I2 min RAm Minute of Right Ascension (J2000)
25- 29 F5.2 s RAs Second of Right Ascension (J2000)
32 A1 --- DE- Sign of the Declination (J2000)
33- 34 I2 deg DEd Degree of Declination (J2000)
36- 37 I2 arcmin DEm Arcminute of Declination (J2000)
39- 42 F4.1 arcsec DEs Arcsecond of Declination (J2000)
45- 56 F12.8 deg GLON Galactic longitude
58- 68 F11.8 deg GLAT Galactic latitude
70- 79 F10.3 mJy Flux Flux density in the channel wavelength
81- 89 F9.3 mJy e_Flux Uncertainty in Flux
91- 92 I2 --- N Number of observations of source
94-102 F9.1 --- S/N Signal-to-noise ratio
104-106 A3 --- Meth Method used to compute the flux (2)
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Note (1): Name in Simbad is [RAS2008] GC-IRACc-NNNNNN
where c is the channel number, and N the ID number
Note (2): Method as follows:
APC = Aperture Corrected Photometry.
PRF = Point Response Function Fitting.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Source identification (NNN)
5- 9 A5 --- Field IRAC sub-array field (1)
11- 12 I2 h RAh Hour of Right Ascension (J2000)
14- 15 I2 min RAm Minute of Right Ascension (J2000)
17- 21 F5.2 s RAs Second of Right Ascension (J2000)
23 A1 --- DE- Sign of the Declination (J2000)
24- 25 I2 deg DEd Degree of Declination (J2000)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000)
30- 33 F4.1 arcsec DEs Arcsecond of Declination (J2000)
35- 46 F12.8 deg GLON Galactic longitude
48- 58 F11.8 deg GLAT Galactic latitude
60- 65 F6.3 mag 3.6mag ? IRAC 3.6 micron band magnitude
67- 71 F5.3 mag e_3.6mag ? Uncertainty in 3.6mag
73- 78 F6.3 mag 4.5mag ? IRAC 4.5 micron band magnitude
80- 84 F5.3 mag e_4.5mag ? Uncertainty in 4.5mag
86- 90 F5.3 mag 5.8mag ? IRAC 5.8 micron band magnitude
92- 96 F5.3 mag e_5.8mag ? Uncertainty in 5.8mag
98-102 F5.3 mag 8.0mag ? IRAC 8.0 micron band magnitude
104-108 F5.3 mag e_8.0mag ? Uncertainty in 8.0mag
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Note (1): Note as follows:
sat = individual sub-array pointings.
sgra = sub-array field centered on SgrA*
quint = sub-array field centered on the Quintuplet cluster
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [SSTGC]
7- 13 I07 --- SSTGC Source identification
15- 16 I2 h RAh Hour of Right Ascension (J2000)
18- 19 I2 min RAm Minute of Right Ascension (J2000)
21- 25 F5.2 s RAs Second of Right Ascension (J2000)
28 A1 --- DE- Sign of the Declination (J2000)
29- 30 I2 deg DEd Degree of Declination (J2000)
32- 33 I2 arcmin DEm Arcminute of Declination (J2000)
35- 38 F4.1 arcsec DEs Arcsecond of Declination (J2000)
41- 49 F9.5 deg GLON Galactic longitude
51- 58 F8.5 deg GLAT Galactic latitude
60 I1 --- 2+1 [0,1] satisfies the "2+1" criterion flag (1)
62 I1 --- loc [0,3] Note about source location (2)
64- 80 A17 --- 2MASS 2MASS identification (HHMMSSss+DDMMSSsA)
82- 87 F6.3 mag Jmag ?=-9.999 2MASS J band magnitude
89- 94 F6.3 mag e_Jmag ?=-9.999 Uncertainty in Jmag
96-103 F8.3 mag Hmag ?=-9.999 2MASS H band magnitude
105-110 F6.3 mag e_Hmag ?=-9.999 Uncertainty in Hmag
112-119 F8.3 mag Ksmag ?=-9.999 2MASS KS band magnitude
121-126 F6.3 mag e_Ksmag ?=-9.999 Uncertainty in Ksmag
128-130 A3 --- q2M [ABCDEFUXZ] 2MASS quality flag in J H K (3)
132-140 A9 --- --- [GC IRAC1-]
141-146 I06 --- ID1 ? Identification in Channel 1 (3.6um)
149-154 F6.3 mag 3.6mag ?=-9.999 Channel 1 magnitude at 3.6um
156-161 F6.3 mag e_3.6mag ?=-9.999 Uncertainty in 3.6mag
163-170 F8.1 --- SNR1 ?=-9.9 Channel 1 signal-to-noise
172 I1 --- f1 [0,4] Channel 1 flag (4)
174-175 I2 --- N1 Channel 1 Coverage (#frames at source position)
177-180 F4.2 --- M/N1 Channel 1 M/N ratio (5)
182-190 A9 --- --- [GC IRAC2-]
191-196 I06 --- ID2 ? Identification in Channel 2 (4.5um)
199-204 F6.3 mag 4.5mag ?=-9.999 Channel 2 magnitude at 4.5um
206-211 F6.3 mag e_4.5mag ?=-9.999 Uncertainty in 4.5mag
213-221 F9.1 --- SNR2 ?=-9.9 Channel 2 signal-to-noise
223 I1 --- f2 [0,4] Channel 2 flag (4)
225-226 I2 --- N2 Channel 2 Coverage (#frames at source position)
228-231 F4.2 --- M/N2 Channel 2 M/N ratio (5)
233-241 A9 --- --- [GC IRAC3-]
242-247 I06 --- ID3 ? Identification in Channel 3 (5.8um)
250-255 F6.3 mag 5.8mag ?=-9.999 Channel 3 magnitude at 5.8um
257-262 F6.3 mag e_5.8mag ?=-9.999 Uncertainty in 5.8mag
264-271 F8.1 --- SNR3 ?=-9.9 Channel 3 signal-to-noise
273 I1 --- f3 [0,4] Channel 3 flag (4)
275-276 I2 --- N3 Channel 3 Coverage (#frames at source position)
278-281 F4.2 --- M/N3 Channel 3 M/N ratio (5)
283-291 A9 --- --- [GC IRAC4-]
292-297 I06 --- ID4 ? Identification in Channel 4 (8.0um)
300-305 F6.3 mag 8.0mag ?=-9.999 Channel 4 magnitude at 8.0um
307-312 F6.3 mag e_8.0mag ?=-9.999 Uncertainty in 8.0mag
314-321 F8.1 --- SNR4 ?=-9.9 Channel 4 signal-to-noise
323 I1 --- f4 [0,4] Channel 4 flag (4)
325-326 I2 --- N4 Channel 4 Coverage (#frames at source position)
328-331 F4.2 --- M/N4 Channel 4 M/N ratio (5)
334-340 A7 --- ID6 Name from table6 (sub-array photometry) (6)
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Note (1): the value '1' indicates that the source satisfies the GLIMPSE
"2+1" criterion: M/N≥0.6 in one IRAC band, M/N≥0.4 in an adjacent
band where M is the number of detections and N, the number of possible
observations.
Note (2): Flag as follows:
0 = source is located in areas of incomplete coverage.
2 = source is located within 40 arcmin on the Central Cluster.
3 = source is located within 42 arcmin of the Quintuplet Cluster.
1 = none of the above
Note (3): JHK photometric quality flag from the 2MASS Catalog as follows:
A = SNR>10
B = SNR>7
C = SNR>5
D = no SNR requirement
E = poor profile-fit photometry
F = detection without photometric uncertainty
U = detection with upper limit on magnitude
X = detection without brightness estimate
ZZZ = no 2MASS counterpart
Note (4): Flag as follows:
0 = source is not detected at the corresponding IRAC band.
1 = magnitude comes from PRF fitting algorithm.
2 = magnitude comes from aperture corrected measurement.
3 = magnitude is greater than corresponding saturation limit.
4 = magnitude comes from sub-array photometry.
Note (5): Ratio between M number of detections over N number of possible
observations (coverage).
Note (6): for sources observed in the sub-array photometry, the name is
* satNNN = source in individual sub-array pointings
* sgraNNN = source in sub-array field centered on SgrA*
* qintNNN = source in sub-array field centered on Quintuplet cluster
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Jun-2009