II/330 Northern sky photometric catalog of 44 million sources (Madsen+ 2013)
A precision multi-band two-epoch photometric catalog of 44 million sources in
the northern sky from a combination of the USNO-B and Sloan Digital Sky Survey
catalogs.
Madsen G.J., Gaensler B.M.
<Astrophys. J. Suppl. Ser., 209, 33 (2013)>
=2013ApJS..209...33M 2013ApJS..209...33M
=2014yCat.2330....0M 2014yCat.2330....0M
ADC_Keywords: Surveys; Photometry, SDSS
Keywords: catalogs - methods: data analysis - quasars: general -
stars: variables: general - techniques: photometric
Abstract:
A key science driver for the next generation of wide-field optical and
radio surveys is the exploration of the time variable sky. These
surveys will have unprecedented sensitivity and areal coverage, but
will be limited in their ability to detect variability on time scales
longer than the lifetime of the surveys. We present a new precision,
multi-epoch photometric catalog that spans 60 yr by combining the US
Naval Observatory-B (USNO-B) and Sloan Digital Sky Survey (SDSS) Data
Release 9 (DR9) catalogs. We recalibrate the photometry of the
original USNO-B catalog and create a catalog with two epochs of
photometry in up to five different bands for 43,647,887 optical point
sources that lie in the DR9 footprint of the northern sky. The
recalibrated objects span a magnitude range 14≲m≲20 and are
accurate to ∼0.1mag. We minimize the presence of spurious
objects and those with inaccurate magnitudes by identifying and
removing several sources of systematic errors in the two originating
catalogs, with a focus on spurious objects that exhibit large apparent
magnitude variations. After accounting for these effects, we find
∼250,000 stars and quasars that show significant (≥4σ)
changes in brightness between the USNO-B and SDSS DR9 epochs. We
discuss the historical value of the catalog and its application to the
study of long time scale, large amplitude variable stars and quasars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 2549344 Recalibration coefficients from small-scale
correction
table1.fits 2880 23018 Table1 in FITS format
table3.dat 342 43647887 Photometric catalog
table3.fits 2880 3031112 Table3 in FITS format
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See also:
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Run SDSS DR9 run number
6- 9 I4 --- Field SDSS DR9 field number
11 I1 --- CamCol SDSS DR9 camcol number
13 I1 --- Usurvey USNOB survey number (1)
15- 17 I3 --- UField USNOB field number in survey
19- 26 F8.6 --- A A coefficient (2)
28- 36 F9.6 --- B B coefficient (2)
38- 46 F9.6 --- C C coefficient (2)
48- 55 F8.6 mag sigmam Standard deviation, m'(USBO)-m(SDSS) (2)
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Note (1): Surveys used for USNO-B1.0:
--------------------------------------------------
# Name Emuls Wavelen. Zones Fld Dates
(nm) Obs.
--------------------------------------------------
0 = POSS-I 103a-O 350-500 -30..+90 936 1949-1965
1 = POSS-I 103a-E 620-670 -30..+90 936 1949-1965
2 = POSS-II IIIa-J 385-540 +00..+87 897 1985-2000
3 = POSS-II IIIa-F 610-690 +00..+87 897 1985-1999
4 = SERC-J IIIa-J 385-540 -90..-05 606 1978-1990
5 = ESO-R IIIa-F 630-690 -90..-05 624 1974-1994
6 = AAO-R IIIa-F 590-690 -90..-20 606 1985-1998
7 = POSS-II IV-N 730-900 +05..+87 800 1989-2000
8 = SERC-I IV-N 715-900 -90..+00 892 1978-2002
9 = SERC-I* IV-N 715-900 +05..+20 25 1981-2002
--------------------------------------------------
Note (2): If there are four or more calibration objects, determine coefficients
A, B, C that minimize the absolute difference |m'(USBO)-m(SDSS)| among the
calibration objects, where m'(USNO)=A*m(UBNO)+B*(color)+C, is the small-scale
recalibrated magnitude of the calibration objects, m(USNO) is the original
USNO-B magnitude, color=(g-r) for bands O, E, J, F and color=(r-i) for band N.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- USNOB Object identification in USNO-B
14- 32 I19 --- OBJID Object identification in DR9 of SDSS-III
34- 43 F10.6 deg RAdeg Right ascension in DR9 (J2000; epoch 2000.0)
45- 54 F10.6 deg DEdeg Declination in DR9 (J2000; epoch 2000.0)
56- 65 F10.4 yr tSDSS Epoch of DR9 observation (decimal years)
67 I1 --- Flag [0/2] Bit mask indicating object is likely an
artifact in USNO-B (1)
69- 74 F6.2 mag O1magU ? Small-scale recalibrated O-band USNO-B
magnitude
76- 81 F6.2 mag OmagU ? Final recalibrated O-band USNO-B magnitude
83- 88 F6.2 mag e_OmagU ? Uncertainty on Omag
90- 99 F10.4 yr tOmagU ? Epoch of O-band observation
101-107 F7.3 mag OmagS ? Magnitude of DR9 object in O band
109-115 F7.3 mag e_OmagS ? Uncertainty in OmagS
117 A1 --- Ocons [FT] Boolean flag indicating consistency
of O-band USNO with other catalogs (2)
119-120 I2 --- q_Omag [0/14]? Bit mask indicating O-band data
quality (3)
122 A1 --- OVar [FT] Boolean flag indicating 4σ
variability (4)
124-129 F6.2 mag E1magU ? Small-scale recalibrated E-band USNO-B
magnitude
131-136 F6.2 mag EmagU ? Final recalibrated E-band USNO-B magnitude
138-143 F6.2 mag e_EmagU ? Uncertainty on Emag
145-154 F10.4 yr tEmagU ? Epoch of E-band observation
156-162 F7.3 mag EmagS ? Magnitude of DR9 object in E band
164-170 F7.3 mag e_EmagS ? Uncertainty in EmagS
172 A1 --- Econs [FT] Boolean flag indicating consistency
of E-band USNO with other catalogs (2)
174-175 I2 --- q_Emag [0/14]? Bit mask indicating E-band data
quality (3)
177 A1 --- EVar [FT] Boolean flag indicating 4σ
variability (4)
179-184 F6.2 mag J1magU ? Small-scale recalibrated J-band USNO-B
magnitude
186-191 F6.2 mag JmagU ? Final recalibrated J-band USNO-B magnitude
193-198 F6.2 mag e_JmagU ? Uncertainty on Jmag
200-209 F10.4 yr tJmagU ? Epoch of J-band observation
211-217 F7.3 mag JmagS ? Magnitude of DR9 object in J band
219-225 F7.3 mag e_JmagS ? Uncertainty in JmagS
227 A1 --- Jcons [FT] Boolean flag indicating consistency
of J-band USNO with other catalogs (2)
229-230 I2 --- q_Jmag [0/15]? Bit mask indicating J-band data
quality (3)
232 A1 --- JVar [FT] Boolean flag indicating 4σ
variability (4)
234-239 F6.2 mag F1magU ? Small-scale recalibrated F-band USNO-B
magnitude
241-246 F6.2 mag FmagU ? Final recalibrated F-band USNO-B magnitude
248-253 F6.2 mag e_FmagU ? Uncertainty on Fmag
255-264 F10.4 yr tFmagU ? Epoch of F-band observation
266-272 F7.3 mag FmagS ? Magnitude of DR9 object in F band
274-280 F7.3 mag e_FmagS ? Uncertainty in FmagS
282 A1 --- Fcons [FT] Boolean flag indicating consistency
of F-band USNO with other catalogs (2)
284-285 I2 --- q_Fmag [0/15]? Bit mask indicating F-band data
quality (3)
287 A1 --- FVar [0,1FT] Boolean flag indicating 4σ
variability (4)
289-294 F6.2 mag N1magU ? Small-scale recalibrated N-band USNO-B
magnitude
296-301 F6.2 mag NmagU ? Final recalibrated N-band USNO-B magnitude
303-308 F6.2 mag e_NmagU ? Uncertainty on Nmag
310-319 F10.4 yr tNmagU ? Epoch of N-band observation (5)
321-327 F7.3 mag NmagS ? Magnitude of DR9 object in N band
329-335 F7.3 mag e_NmagS ? Uncertainty in NmagS
337 A1 --- Ncons [FT] Boolean flag indicating consistency
of N-band USNO with other catalogs (2)
339-340 I2 --- q_Nmag [0/14]? Bit mask indicating N-band data
quality (3)
342 A1 --- NVar [FT] Boolean flag indicating 4σ
variability (4)
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Note (1): See Section 2.4; the zeroth bit indicates the object is classified as
a diffraction spike; the first bit indicates the object is classified as
reflection halo artifact as determined by Barron et al. (2008AJ....135..414B 2008AJ....135..414B).
0 = source not spurius
1 = diffraction spike (0.05%)
2 = reflection halo artifact (0.002%)
Note (2): See Section 5; this flag is set to a null value (F) if the
consistency could not be determined.
Note (3): The flag is composed of four bits, is represented as an integer in
base 10, and can be filtered using bitwise operators. For example, if an
object is within the exclusion radius of a bright star and is blended with one
or more DR9 objects and, but is not blended with USNO-B objects and has a
e_mUSNO that is not derived from sparse data, its quality flag is 20+22=5.
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Bit Mask Values for Quality Flags:
-------------------------------------------------------------------------
0 = Object is within exclusion radius of a bright star (see Section 3.1)
1 = Object is blended with one or more USNO-B objects (see Section 3.2)
2 = Object is blended with one or more DR9 objects (see Section 3.2)
3 = Uncertainty in recalibrated magnitude (e_mUSNO) is derived from sparse
data (see Section 4.2)
-------------------------------------------------------------------------
Note (4): This flag is set to true (T) if the object satisfies the criteria
described in Section 8.2 for 4σ variables
Note (5): See Section 2.1; rows with null values for tUSNO are from N-band
plates with unidentifiable epochs.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 07-Mar-2014