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J/A+A/418/509       Chandra observation of M67             (Van Den Berg+, 2004)

A Chandra observation of the old open cluster M67. Van Den Berg M., Tagliaferri G., Belloni T., Verbunt F. <Astron. Astrophys., 418, 509-523 (2004)> =2004A&A...418..509V
ADC_Keywords: Clusters, open ; X-ray sources Mission_Name: Chandra Keywords: stars: activity - stars: binaries: general - stars: blue stragglers - open clusters and associations: individual: M67 - X-rays: binaries Abstract: We present the results of a 47-ks Chandra/ACIS observation of the old open cluster M67. We detected 25 proper-motion cluster members (including ten new sources) and 12 sources (all new) that we suspect to be members from their locations close to the main sequence (1<B-V<1.7). Of the detected members, 23 are binaries. Description: table1.dat summarizes the X-ray properties of the 158 sources detected by Chandra, and lists the ROSAT (Belloni et al., 1998A&A...335..517B) and optical (candidate) counterparts. table4.dat gives the estimated positions of fifteen faint candidate optical counterparts that were identified by eye in a deep ESO Imaging Survey (EIS) V-band image of M67. These sources are not included in the corresponding EIS source catalogue (Momany et al., 2001A&A...379..436M). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 114 158 Catalogue of Chandra sources in the field of M67 notes.dat 79 33 Individual notes table4.dat 71 15 Estimated positions of faint optical counterparts
See also: V/52 : Photometry and Proper Motions in M67 (Frolov+ 1986) II/123 : UBV Photometry of Faint Stars (V>14.5) in M67 (Frolov+ 1986) J/AJ/106/181 : CCD photometry of open cluster M67 (Montgomery+ 1993) J/AJ/112/628 : BATC Color Survey of M67 (Fan+ 1996) J/A+A/382/899 : BVI photometry in M67 (Stassun+, 2002) J/BaltA/7/369 : M67 CCD photometry (Boyle+, 1998) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- CX Chandra source identification 4 A1 --- Sig Indicator of significance of detection (1) 7- 11 F5.2 arcmin Daim Distance from the telescope aimpoint 14 I1 h RAh Right ascension (J2000) (2) 16- 17 I2 min RAm Right ascension (J2000) 19- 24 F6.3 s RAs Right ascension (J2000) 26- 30 F5.3 s e_RAs Error in right ascension (2) 33 A1 --- DE- Declination sign (J2000) 34- 35 I2 deg DEd Declination (J2000) (2) 37- 38 I2 arcmin DEm Declination (J2000) 40- 44 F5.2 arcsec DEs Declination (J2000) 46- 49 F4.2 arcsec e_DEs Error in declination (2) 52- 54 I3 ct CRateb Background-corrected counts between 0.3-7keV 56- 57 I2 ct e_CRateb Error in background-corrected counts 60- 64 F5.2 ct/ks CRate Net count-rate between 0.3-7keV (3) 67 A1 --- B [SHT] Energy band of most significant detection (4) 70- 74 F5.2 --- HR ? Hardness ratio (5) 76- 79 F4.2 --- e_HR ? Error in hardness ratio 82- 83 I2 --- X ? (Candidate) ROSAT counterpart in Belloni et al. (1998A&A...339..431B), [BVM98] M 67 NN in Simbad 86-101 A16 --- Opt (Candidate) optical counterpart (6) 104-108 A5 --- n_CX Notes on individual sources, detailed in notes.dat file 111-114 F4.2 arcsec dXO ? Distance between Chandra and optical source
Note (1): An '*' indicates that the source is detected with the significance threshold set to 10-6 but not with the threshold set to 10-7. Note (2): Positions are derived from the 0.3-7keV band image, and are corrected for a systematic offset 'delta' relative to the EIS optical positions: delta(RA)=(RA)X-(RA)opt=-0.23arcsec and delta(DE)=(DE)X-(DE)opt=-0.20arcsec. The errors on RA and DE in columns 7 and 12 are the 1-sigma 'wavdetect' errors including the corrections for small count numbers (See Sect.2.3 of paper). These are often much smaller than the uncertainty in the absolute positions, i.e. than the uncertainty in the offset values delta(RA) and delta(DE) (about 0.3arcsec). Note (3): Corrected for background and vignetting Note (4): Energy bands are: S=0.3-2keV (soft), H=2-7keV (hard), T=0.3-7keV (total) Note (5): Hardness ratio is defined as (H'-S')/(H'+S') where S' and H' are the number of counts between 0.5-1 and 1-7keV respectively. Only listed if the error on the hardness ratio is less than 0.4. Note (6): The name of the counterpart is selected from (in order of preference): Sanders (1977A&AS...27...89S) (S), Momany et al. (2001A&A...379..436M) (E), and Fan et al. (1996AJ....112..628F) (F). Sources that are identified by eye with objects listed in neither catalogue are labelled with 'faint' (see table4.dat).
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1 A1 --- Code Note letter 4- 79 A76 --- Note Text of the note
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 3 I3 --- CX Chandra source identification 5- 6 I2 --- X ? Identification of ROSAT candidate counterpart in Belloni+Tagliaferri (1998A&A...335..517B) 7 A1 --- u_X Uncertainty flag for ROSAT identification (1) 9 I1 h RAh Right ascension (J2000) 11- 12 I2 min RAm Right ascension (J2000) 14- 18 F5.2 s RAs Right ascension (J2000) 20 A1 --- DE- Declination sign 21- 22 I2 deg DEd Declination (J2000) 24- 25 I2 arcmin DEm Declination (J2000) 27- 30 F4.1 arcsec DEs Declination (J2000) 32 A1 --- n_X Note on ROSAT identification (2)
Note (1): Cross-identification with ROSAT source is uncertain because of a relatively large offset between the Chandra and ROSAT positions; see the discussion in Sect. 3.2 of the paper. Note (2): For Chandra sources with a ROSAT counterpart, an 'N' in this column indicates that the identification with the optical counterpart is new and was not yet suggested by Belloni et al. (1998A&A...339..431B).
Acknowledgements: Maureen Van den Berg History: * 26-Apr-2004: Original version * 26-Jan-2007: Unit of e_RAs originally specified as "arsec", was changed to s (seconds of time)
(End) Maureen van den Berg [CfA], Patricia Bauer [CDS] 26-Apr-2004
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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