J/AJ/163/131 USNO-UBAD catalog of bright stars (Munn+, 2022)
Accurate Ground-based Astrometry of Naked-eye Stars: The United States Naval
Observatory Bright-star Astrometric Database.
Munn J.A., Subasavage J.P., Harris H.C., Tilleman T.M.
<Astron. J., 163, 131 (2022)>
=2022AJ....163..131M 2022AJ....163..131M
ADC_Keywords: Photometry, VRI; Positional data; Proper motions
Keywords: Astrometry
Abstract:
We present the United States Naval Observatory (USNO) Bright-star
Astrometric Database (UBAD), a current-epoch high-accuracy astrometric
catalog. The catalog consists of 364 bright northern hemisphere stars,
including all but five such stars with either V<3.5 or with I<3.2 and
V<6, as well as a large fraction of slightly fainter stars; 36 of the
brightest catalog stars are not included in Gaia Early Data Release 3
(EDR3). Observations were conducted with the USNO Flagstaff Station
Kaj Strand 61 inch Astrometric Reflector. Target stars were imaged
through a small 12.5mag neutral-density spot, while the remainder of
the stars in the field of view were unattenuated. This allowed for
unsaturated images of the bright target stars to be calibrated
directly against much fainter reference stars from Gaia EDR3. The
median position errors are 1.9mas in both R.A. and decl. at the
catalog epoch of 2017.0, with 90% of catalog stars having errors less
than 2.6mas; systematic errors are 1-3 mas. Combining UBAD
observations with Hipparcos-2 positions yields proper motions with
median errors of 0.045 and 0.049mas/yr in R.A. and decl.,
respectively, with 90% of stars having errors less than 0.1mas/yr;
systematic errors are about 0.1mas/yr. Single-frame accuracy for
positions of the target stars is typically 5-6mas. Gaia EDR3
astrometry for these bright stars, which are heavily saturated in the
Gaia observations, is validated over the magnitude range 2≲G≲6.
Description:
Observations were conducted with the United States Naval Observatory
(USNO) Flagstaff Station Kaj Strand 61 inch Astrometric Reflector. The
camera was built in-house using a 2048x4102 e2v CCD with 15micron
pixels, which in the 61inch focal plane yields a pixel scale of
0.2025"/pixel. A clear filter covers the detector with a 5mm diameter
12.5mag neutral-density spot deposited in the center on the sky-facing
surface of the filter. The target star is observed through the spot,
which has measured attenuations of 12.48mag in V and 12.89mag in I.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 112 364 United States Naval Observatory Bright-star
Astrometric Database catalog
table2.dat 96 4807 Single-epoch positions
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See also:
B/simbad : Simbad objects catalogue (M.Wenger 2000)
B/sb9 : 9th Catalogue of Spectroscopic Binary Orbits (Pourbaix+ 2004-2014)
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
V/122 : SB9; 9th Catalogue of Spectroscopic Binary Orbits (Pourbaix+ 2005)
J/AJ/129/2420 : Proper motion derivatives of binaries (Makarov+, 2005)
J/AJ/154/147 : Astrometry&photometry late-type dwarfs&subdwarfs (Dahn+, 2017)
J/ApJ/867/105 : ATLAS all-sky stellar ref. cat, ATLAS-REFCAT2 (Tonry+, 2018)
J/AJ/162/44 : Near-IR spectrum HIP109427 with SCExAO/CHARIS (Steiger+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP [677/118131] Hipparcos identifier
8- 18 F11.7 deg RAdeg [2/360] Right Ascension (ICRS, epoch 2017.0)
20- 24 F5.2 mas e_RAdeg [1/69] Error in RAdeg*cos(DEdeg)
26- 36 F11.7 deg DEdeg [0.1/78] Declination (ICRS, epoch 2017.0)
38- 42 F5.2 mas e_DEdeg [1.6/45] Error in DEdeg
44- 52 F9.3 mas/yr pmRA [-1094/1083] Proper motion in Right Ascension
*cos(DE)
54- 60 F7.4 mas/yr e_pmRA [0.01/61] Error in pmRA
62- 70 F9.3 mas/yr pmDE [-2000/819] Proper motion in declination
72- 78 F7.4 mas/yr e_pmDE [0.02/40] Error in pmDE
80- 81 I2 --- ni [0/42] Number of UBAD i observations used in
fit
83- 84 I2 --- nz [0/20] Number of UBAD z observations used in
fit
86 I1 --- used? [0/1] Hipparcos-2 used flag (1)
88- 92 F5.2 mas rms-RA [1.04/14.1] RMS of the fit in right ascension
(2)
94- 98 F5.3 --- chi2-RA [0.08/7.74] Reduced chi-square of fit in RA
100-104 F5.2 mas rms-DE [1.24/13] RMS of the fit in declination (2)
106-110 F5.3 --- chi2-DE [0.1/7.87] Reduced chi-square of fit in DE
112 A1 --- Class Visual classification of the target (3)
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Note (1): Flags as follows:
1 = The Hipparcos-2 coordinate was used in the fit (331 occurrences)
0 = The Hipparcos-2 coordinate was not used in the fit (33 occurrences)
Note (2): Fit RMS values exclude the Hipparcos-2 position.
Note (3): Claddification as follows:
s = single (352 occurrences)
n = resolved neighbor (2 occurrences)
r = resolved blend (4 occurrences)
u = unresolved blend (6 occurrences)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 --- Epoch [2016/2021] Observation epoch
13- 18 I6 --- HIP [677/118131] Hipparcos identifier
20- 30 F11.7 deg RAdeg [2/360] Right ascension (ICRS astrometric place)
32- 36 F5.2 mas e_RAdeg [3/28] Error in RAdeg
38- 47 F10.7 deg DEdeg [-2/78] Declination (ICRS, astrometric place)
49- 53 F5.2 mas e_DEdeg [3/48] Error in DEdeg
55- 60 F6.1 s Texp [15/3333] Exposure time
62- 66 F5.3 --- airmass [1/1.45] Weighted mean airmass
68- 70 I3 --- Nstars [6/183] Number of Gaia stars used in solution
72- 77 F6.2 mas RA-RMS [0.52/120] RMS of plate solution in right
ascension
79- 84 F6.2 mas DE-RMS [1.09/197] RMS of plate solution in declination
86- 90 F5.3 arcsec seeing [0.65/3.89] Clipped mean FWHM of detections on
image
92- 96 F5.3 --- elong [1/1.25] Clipped mean elongation of detections
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie fix [CDS], 09-May-2022