II/287 Northern Sky Variability Survey (NSVS) (Wozniak+, 2004)
Northern Sky Variability Survey: public data release.
Wozniak P.R., Vestrand W.T., Akerlof C.W., Balsano R., Bloch J.,
Casperson D., Fletcher S., Gisler G., Kehoe R., Kinemuchi K., Lee B.C.,
Marshall S., McGowan K.E., McKay T.A., Rykoff E.S., Smith D.A.,
Szymanski J., Wren J.
<Astron. J., 127, 2436-2449 (2004)>
=2004AJ....127.2436W 2004AJ....127.2436W
ADC_Keywords: Stars, variable ; Surveys
Keywords: astronomical data bases: miscellaneous - catalogs - stars: general -
stars: variables: other - surveys
Abstract:
The Northern Sky Variability Survey (NSVS) is a temporal record of the
sky over the optical magnitude range from 8 to 15.5. It was conducted
in the course of the first-generation Robotic Optical Transient Search
Experiment (ROTSE-I) using a robotic system of four comounted
unfiltered telephoto lenses equipped with CCD cameras. The survey was
conducted from Los Alamos, New Mexico, and primarily covers the entire
northern sky. Some data in southern fields between declinations 0°
and -38° are also available, although with fewer epochs and
noticeably lesser quality. The NSVS contains light curves for
approximately 14 million objects. With a 1-yr baseline and typically
100-500 measurements per object, the NSVS is the most extensive record
of stellar variability across the bright sky available today. In a
median field, bright unsaturated stars attain a point-to-point
photometric scatter of ∼0.02mag and position errors within 2. At
Galactic latitudes |b|<20°, the data quality is limited by severe
blending due to the ∼14" pixel size. We present basic characteristics
of the data set and describe data collection, analysis, and
distribution. All NSVS photometric measurements are available for
on-line public access from the Sky Database for Objects in Time-Domain
(SkyDOT) at Los Alamos National Laboratory. Copies of the full survey
photometry may also be requested on tape.
Acknowledging the usage of NSVS:
We request that the researchers using NSVS in their published work
include the following statement to acknowledge the source of data:
This publication makes use of the data from the Northern Sky
Variability Survey created jointly by the Los Alamos National
Laboratory and University ofMichigan. The NSVS was funded by the
Department of Energy, the National Aeronautics and Space
Administration, and the National Science Foundation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
skydot.dat 61 19995106 Skydot catalog
fields.dat 44 644 Fields
frames.dat 203 184006 Frames
id/* . 634 *Individual files for skydotID
noid/* . 644 Individual files for skydotNOID
synonym.dat 28 14582566 Synonym
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Note on id/*: file skydotID_104a.dat.gz incomplete.
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Byte-by-byte Description of file: skydot.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Median right ascension of centroid (J2000)
11- 13 I3 10-5deg e_RAdeg Mean error on RAdeg
15- 23 F9.5 deg DEdeg Median right ascension of centroid (J2000)
25- 27 I3 10-5deg e_DEdeg Mean error on DEdeg
30- 35 F6.3 mag mag Unfiltered optical magnitude 450-1000nm,
effective wavelength or R band, median
value from "good" points
37- 41 F5.3 mag e_mag Mean error on mag around median
43- 47 F5.3 mag emag Median error bar of "good" points
49- 51 I3 --- Nobs Number of "good" points
53- 55 I3 --- N1 Number of all points without RADECFLIP Cag
57- 59 I3 --- Ndet Number of all object detections
61 I1 --- flag [0,3] Object flags
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Byte-by-byte Description of file: fields.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Field Field name (NNNa) (001a ---> 0161d)
6- 10 F5.1 deg RAdeg Right ascension of field center (J2000.0)
in decimal degrees
12- 16 F5.1 deg DEdeg Declination of field center (J2000.0)
in decimal degrees
18- 22 F5.1 deg GLON Galactic longitude of field center
24- 28 F5.1 deg GLAT Galactic latitude of field center
30- 32 I3 --- Nfr Number of frames
34- 38 I5 --- Nobj Number of catalog objects
40- 44 F5.3 mag sig-ph Limiting photometric scatter
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Byte-by-byte Description of file: frames.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/644] Frame ID
5- 24 A20 --- Field Field ID ou Image file name
26- 27 A2 --- Cam [1abcd ] Camera ID (ABCD)
29- 39 F11.5 d JD Julian date (JD-2400000)
41- 51 F11.5 s Time Time of observation in UT seconds
53- 62 A10 "YYYY-MM-DD" Date.date UT date of observation
63 A1 --- --- [T]
64- 74 A11 "h:m:s" Date.time UT date of observation
76- 79 F4.1 s ExpTime Exposure time
81- 87 F7.1 ct bkg Sky background
89- 93 F5.1 ct e_bkg Standard deviation of sky background
95- 99 F5.3 pix e_pos Standard deviation around the fit to
positions of Tycho stars
101-106 F6.3 mag zpoffset Median magnitude offset with respect to
Tycho stars
108-112 F5.3 mag e_zpoffset Standard deviation of magnitude offsets
114-120 F7.3 mag mlim Limiting magnitude
122-127 F6.3 mag msat Saturation magnitude
129-133 I5 --- Nobj Number of objects detected by SExtractor
135-139 I5 --- Nobj2 Number of objects actually measured
141-144 I4 --- Nmatch Number of Tycho stars used in magnitude
matching
146-151 F6.2 deg dmoon Angular distance between frame center and
the Moon
153-157 F5.2 deg elev Elevation of frame center with respect to
horizon
159-164 F6.2 deg azimuth Azimuth of frame center
166-171 F6.2 deg mountRA RA J2000.0 position of telescope mount
173-178 F6.2 deg mountDE DE J2000.0 position of telescope mount
180-184 F5.2 deg oRA ΔRAcosDE offset between frame center
and mount position
186-190 F5.2 deg oDE ΔDE offset between frame center
and mount position
192 I1 mag maprms Standard deviation of the photometric
correction map
194-199 F6.4 --- Npix Number of valid pixels in photometric
correction map
201-203 I3 --- Flag Frame flags
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Byte-by-byte Description of file: id/*
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Bytes Format Units Label Explanations
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1- 8 I8 --- Object Object ID
10- 17 I8 --- Frame [1/184006] Frame ID
19- 22 I4 3.125x10-6deg oRA Offset in right ascension (J2000.0) from
median centroid (in 1/32000°)
24- 27 I4 3.125x10-6deg oDE Offset in declination (J2000.0) from
median centroid (in 1/32000°)
29- 33 I5 mmag magcorr Corrected object magnitude
35- 39 I5 mmag e_magcorr Magnitude error
41- 45 I5 --- Flags Measurement flags
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Byte-by-byte Description of file: noid/* noid2/*
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Bytes Format Units Label Explanations
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1- 8 I8 --- Frame [1/184006] Frame ID
10- 18 F9.5 deg RAdeg [] Right ascension (J2000.0) of object
20- 28 F9.5 deg DEdeg Declination (J2000.0) of object
30- 34 I5 mmag magcorr Corrected object magnitude
36- 38 I3 mmag e_magcorr Magnitude error
40- 44 I5 --- Flags Measurement flags
46- 55 I10 --- ID HTM ID for quick spatial queries on the sphere
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Byte-by-byte Description of file: synonym.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- Obj1 First object ID
10- 17 I8 --- Obj2 Second object ID
19- 28 E10.8 deg Sep Spherial distance (<1pixel)
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History:
ftp://skydot.lanl.gov/pub/projects/skydot/nsvs/red_variables/
(End) Patricia Vannier [CDS] 23-Nov-2004