J/A+A/548/A16 Improved astrometry bor BE74 stars (Howarth, 2012)
Improved astrometry for the Bohannan & Epps catalogue.
Howarth I.D.
<Astron. Astrophys. 548, A16 (2012)>
=2012A&A...548A..16H 2012A&A...548A..16H
ADC_Keywords: Positional data ; Cross identifications ; Stars, emission
Keywords: astrometry - stars: emission-line - Magellanic Clouds
Abstract:
Accurate astrometry is required to reliably cross-match 20th-century
catalogues against 21st-century surveys. The present work aims to
provide such astrometry for the 625 entries of the Bohannan & Epps
(BE74; 1974A&AS...18...47B 1974A&AS...18...47B) catalogue of Hα emission-line stars.
BE74 targets have been individually identified in digital images and,
in most cases, unambiguously matched to entries in the UCAC4 (I/322)
astrometric catalogue.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 165 647 *Astrometry for BE74 targets (corrected for small
zero-point offsets as described in the text)
table2.dat 80 116 Notes on individual objects
table3.dat 65 202 Positional matches between measured BE74
co-ordinates and Skiff's results for HDE, Sk,
and LHA 120-S targets, within a 5 arcsec radius
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Note on table1.dat: Remaining data are representative measurements from UCAC4
(via CDS/Vizier, Cat. I/322). Where available, the UCAC4 astrometry is to be
preferred. Note that additional information is available in UCAC4, including
proper motions, which are generally negligible for the BE74 sources.
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See also:
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [BE74] Sequential number
4 A1 --- m_[BE74] Multiplicity index on [BE74]
(? when no positions measured)
8- 9 I2 h RAh ? Measured right ascension (J2000)
11- 12 I2 min RAm ? Measured right ascension (J2000)
14- 18 F5.2 s RAs ? Measured right ascension (J2000)
21 A1 --- DE- ? Measured declination sign (J2000)
22- 23 I2 deg DEd ? Measured declination (J2000)
25- 26 I2 arcmin DEm ? Measured declination (J2000)
28- 31 F4.1 arcsec DEs ? Measured declination (J2000)
37- 38 I2 h RA4h ? Matching UCAC4 right ascension (J2000)
40- 41 I2 min RA4m ? Matching UCAC4 right ascension (J2000)
43- 48 F6.3 s RA4s ? Matching UCAC4 right ascension (J2000)
50 A1 --- DE4- ? Matching UCAC4 declination sign (J2000)
51- 52 I2 deg DE4d ? Matching UCAC4 declination (J2000)
54- 55 I2 arcmin DE4m ? Matching UCAC4 declination (J2000)
57- 61 F5.2 arcsec DE4s ? Matching UCAC4 declination (J2000)
67- 76 A10 --- UCAC4 UCAC4 designation (ZZZ-NNNNNN)
80- 82 I3 mas ePos ? Total mean error on position at Ep=J2000 (3)
84- 89 F6.3 mag f.mag ? UCAC4 fit model magnitude (579-642nm) (4)
91 I1 --- of [0/9]? UCAC4 object classification flag (6)
93- 94 I2 --- db [0/36]? UCAC4 double star flag (7)
99-104 F6.3 mag Jmag ? 2MASS J magnitude
106-111 F6.3 mag Kmag ? 2MASS Ks magnitude
113-118 F6.3 mag Bmag ? B magnitude from APASS (12)
120-125 F6.3 mag Vmag ? V magnitude from APASS (12)
127-132 F6.3 mag rmag ? r magnitude from APASS (12)
134 I1 --- H [0/9]? Hipparcos/Tycho flag (15)
136-165 A30 --- Note Note
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Note (3): taking into account the propagation of the proper motion error
between the mean epoch and J2000.
Note (4): systematic errors are expected to be below 0.1mag.
Note (6): the object type flag is used to identify possible problems with a star
and has the following meaning:
0 = good, clean star, no known problem
1 = near overexposed star
2 = possible streak object
3 = high proper motion (HPM) star
4 = actually use external HPM data instead of UCAC4 observed data
(accuracy of positions varies between catalogs)
5 = poor proper motion solution, report only CCD epoch position
6 = substitute poor astrometric results by FK6/Hip/Tycho-2 data
7 = added supplement star (no CCD data) from FK6/Hip/Tycho-2 data,
and 2 stars added from high proper motion surveys
8 = high proper motion solution in UCAC4, star not matched with PPMXL
9 = high proper motion solution in UCAC4, discrepant motion to PPMXL
Note (7): The double star flag is used to indicate the type/quality
of double star fit. It is a combination of 2 flags, dsf+dst:
* dsf = double star flag, represents the overall classification:
0 = single star
10 = component #1 of "good" double star
20 = component #2 of "good" double star
30 = blended image
* dst = double star type, derived from pixel data image profile fits
(largest value of all images used for this star):
0 = no double star, not sufficient #pixels or elongation
to even call double star fit subroutine
1 = elongated image but no more than 1 peak detected
2 = 2 separate peaks detected -> try double star fit
3 = secondary peak found on each side of primary
4 = case 1 after successful double fit (small separation, blended image)
5 = case 2 after successful double fit (most likely real double)
6 = case 3 after successful double fit (brighter secondary picked)
Note (12): Data are from the AAVSO Photometric all-sky survey (APASS) DR6
plus single observation stars kindly provided by A.Henden. For bright
stars the Bmag and Vmag columns contain the Hipparcos/Tycho Bt and Vt
mags respectively, whenever there is no APASS B or V available and
valid Bt or Vt mags were found. The errors flagged with "-" are formal
errors estimated from the S/N, while the "normal" errors (flagged with
".") are from the official release data error estimates (at least 2
observations per star).
Note (15): The FK6-Hipparcos-Tycho-source-flag has the following meaning:
0 = not a Hipparcos or Tycho star
1 = Hipparcos 1997 version main catalog (Cat I/239)
2 = Hipparcos double star annex
3 = Tycho-2 (Cat. I/259)
4 = Tycho annex 1
5 = Tycho annex 2
6 = FK6 position and proper motion (instead of Hipparcos data)
7 = Hippparcos 2007 solution position and proper motion (Cat. I/311)
8 = FK6, only PM substitution (not in UCAC4 data)
9 = Hipparcos 2007, only proper motion substituted (Cat. I/311)
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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- 3 I3 --- [BE74] Sequential number
6- 80 A75 --- Notes Notes (1)
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Note (1): acronyms used:
* 'BE74' refers to Bohannan & Epps 1974A&AS...18...47B 1974A&AS...18...47B;
* 'HW' to charts from the Hodge & Wright Atlas (Hodge & Wright 1967,
The Large Magellanic Clous (Smithsonian Press, Washington D.C.);
* 'RPs' to emission-line stars catalogued by Reid & Parker
(2012MNRAS.425..355R 2012MNRAS.425..355R, RP12) and
* 'DSS2' to the red Digital Sky Survey images accessed through Aladin.
* 'A','B' etc. refers to separate entries in Table 1.
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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- 3 I3 --- [BE74] BE74 number (use in conjunction with Table 1)
4 A1 --- n_[BE74] Multiplicity index on [BE74]
8- 16 A9 --- HDE HDE match
19- 22 F4.2 arcsec offHDE ? HDE match offset
27- 36 A10 --- Sk Sk match
38- 41 F4.2 arcsec offSk ? Sk match offset
46- 58 A13 --- LHA LHA12-S match
62- 65 F4.2 arcsec offLHA ? LHA12-S match offset
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Acknowledgements:
Ian Howarth, idh(at)star.ucl.ac.uk
(End) Francois Ochsenbein [CDS] 05-Oct-2012