ACDS V10.0 - Fri Aug 28 15:26:15 CEST 2020
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Detailed Description of I/297 :
NOMAD Catalog (Zacharias+ 2005)
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Note : this is the description file of the original catalog.
This HTML page corresponds well to the original description, but some minor
changes in the format may have been introduced in the FITS output
files in order to allow for arithmetic operations on quantities
such as coordinates and times. h:m:s and d:m:s units are normally
converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the
units; the value given in the HTML files supersedes the value indicated in the ReadMe
file for this catalogue.
I/297 NOMAD Catalog (Zacharias+ 2005)
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Naval Observatory Merged Astrometric Dataset (NOMAD)
Zacharias N., Monet D.G., Levine S.E., Urban S.E., Gaume R., Wycoff G.L.
<San Diego AAS Meeting, January (2005)>
=2004AAS...205.4815Z
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ADC_Keywords: Positional data ; Proper motions ; Surveys ;
Photometry, photographic ; Photometry, infrared
Description:
The Naval Observatory Merged Astrometric Dataset (NOMAD) contains
astrometric and photometric data for over 1 billion stars derived from
the Hipparcos (I/239), Tycho-2 (I/259), UCAC2 (I/289), and USNO-B1.0
(I/284) catalogs for astrometry and optical photometry, supplemented
by 2MASS (II/246) near-infrared photometry. For each unique star the
"best" astrometric and photometric data are chosen from the source
catalogs and merged into a single dataset. A sequence of priorities is
followed and NOMAD contains flags to identify the source catalogs and
gives cross-reference identifications. This first release of NOMAD is
not a compiled catalog; that is, if a star is identified in more than
1 of the above mentioned catalogs, only 1 catalog entry is chosen.
Thus the local and global systematic errors of the various source
catalogs will be present in this version of NOMAD. All source catalogs
astrometric data are on the International Celestial Reference System
within the limitations of the source catalogs.
For more information, see
https://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/nomad
A dedicated remote query program can be downloaded from
http://cdsweb.u-strasbg.fr/doc/cdsclient.html
File Summary:
FileName Lrecl Records Explanations
× 80 . This file
× ReadMe 80 . This file
× out.sam 167 1523 Example of the an output of NOMAD-1
See also:
https://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/nomad : NOMAD
Home Page
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
I/289 : UCAC2 Catalogue (Zacharias+ 2004)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: out.sam
Bytes Format Units Label Explanations
1- 12 A12 --- NOMAD1 NOMAD-identifier (1)
14- 25 A12 --- USNO-B1 Identifier in USNO-B1 (Cat. I/284) (1)
27- 34 I8 --- UCAC2 ? Number in UCAC2 (Cat. I/289)
36- 47 A12 --- Tycho-2 ? Identification in Tycho-2 or Hipparcos (2)
48 A1 --- f_Tycho-2 [*] when distance NOMAD1/Tycho-2 > 1arcsec
49- 50 A2 --- YM [YM.] Existence in YB6 or 2MASS (Cat. II/246)
52- 62 F11.7 deg RAdeg Right ascension in ICRS, Ep=J2000
63- 73 F11.7 deg DEdeg Declination in ICRS, Ep=J2000
75 A1 --- r [BCMYTH] Source of position (3)
77- 80 I4 mas e_RAdeg Mean error on RAdeg (at epRA)
82- 85 I4 mas e_DEdeg Mean error on DEdeg (at epDE)
87- 94 F8.1 mas/yr pmRA Proper motion in RA (*cos(Dec))
96-103 F8.1 mas/yr pmDE Proper motion in Declination
105-109 F5.1 mas/yr e_pmRA Mean error on pmRA
111-115 F5.1 mas/yr e_pmDE Mean error on pmDE
117-122 F6.3 mag Bmag ?Blue magnitude
123 A1 --- r_Bmag [BCMYTHo] Origin of Bmag (3)
125-130 F6.3 mag Vmag ?Visual magnitude
131 A1 --- r_Vmag [BCMYTH] Origin of Vmag (3)
133-138 F6.3 mag Rmag ?Red magnitude
139 A1 --- r_Rmag [BCMYTHe] Origin of Rmag (3)
141-146 F6.3 mag Jmag ?Infrared J magnitude (from 2MASS)
148-153 F6.3 mag Hmag ?Infrared H magnitude (from 2MASS)
155-160 F6.3 mag Kmag ?Infrared K magnitude (from 2MASS)
162-166 A5 --- Xflags [0-9a-f] Hexadecimal flags (4)
167 A1 --- R [R*] Recommended (R) or Problematic (*) (4)
Note (1): NOMAD and USNO designations consist in 2 numbers
separated by a dash of the form: zone-number
where zone (0000-1799) indicates a declination strip from the South
Pole (0.1deg wide), and number is a sequential number increasing
with right ascension.
Note (2): The Tycho-2 number (Cat. I/259) is made of 3 numbers separated
by 2dashes, while Hipparcos (Cat. I/239) is a sequential number.
Note (3): Sources of the values are defined as follows:
B = USNO-B1.0 (Monet et al., Cat. I/284)
C = UCAC2 (Zacharias et al., Cat. I/289)
M = 2MASS catalog of point sources (Cutri et al., Cat. II/246)
Y = YB6 Catalog (USNO, unpublished)
T = Tycho-2 Catalog (Hog et al., 2000, Cat. I/259)
H = Hipparcos catalog (Table I/239/hip_main)
o = Palomar-I blue (O) plate (for Bmag)
e = Palomar-I red (E) plate (for Rmag)
Note (4): Flags are written in hexadecimal (symbols 0-f) with the
following meaning:
00001 = UBBIT : Fails Blaise's test for USNO-B1.0 star
00002 = TMBIT : Fails Roc's test for clean 2MASS star
00004 = YB6 : Included in YB6 catalog (Y)
00008 = 2MASS : Included in 2MASS catalog (M)
00010 = TYBIT : Astrometry comes from Tycho2 catalog (T)
00020 = XRBIT : Alternative correlations for same (RA,Dec)
00040 = ITMBIT : Alternative correlations for same 2MASS ID
00080 = IUCBIT : Alternative correlations for same UCAC-2 ID
00100 = ITYBIT : Alternative correlations for same Tycho2 ID
00200 = OMAGBIT : Blue magnitude from O (not J) plate (o)
00400 = EMAGBIT : Red magnitude from E (not F) plate (e)
00800 = TMONLY : Object found only in 2MASS catalog (M)
01000 = HIPAST : Ast from Hipparcos catalog (H)
02000 = SPIKE : USNO-B1.0 diffraction spike bit set
04000 = TYCONF : Tycho2 confusion flag set
08000 = BSCONF : Bright star has nearby faint source
10000 = BSART : Faint source is bright star artifact
20000 = USEME : Recommended astrometric standard
* = one of SPIKE|YCONF|BSCONF|BSART|XRBIT|ITMBIT|IUCBIT|ITYBIT set
R = USEME (recommended astrometric standard)
History:
Prepared by Dave Monet.
Acknowledgements:
It is a pleasure to thank Dave Monet who forwarded a copy of the
NOMAD catalog to CDS.
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(End) Francois Ochsenbein [CDS] 09-Nov-2005