J/A+A/vol/page An XMM-Newton view of NGC 6231 (Sana+ 2006) =============================================================================== An XMM-Newton view of the NGC 6231 young open cluster: I. The catalogue H. Sana, E. Gosset, G. Rauw, H. Sung and J.-M. Vreux =2006A&A...VVV.ppppI (SIMBAD/NED BibCode) =============================================================================== ADC_Keywords: Clusters, open ; Cross identifications ; Photometry, UBVRI ; Stars, OB ; Stars, pre-main sequence ; X-ray sources Keywords: Open clusters and associations: individual: NGC 6231 -- X-rays: individuals: NGC 6231 -- X-rays: stars -- Stars: early-type -- Catalogues Abstract: We present the results of an X-ray campaign towards the young open cluster NGC 6231. The XMM-Newton observations, of a total duration of about 180 ks, reveals that NGC 6231 is very rich in the X-ray domain too. Indeed, 610 X-ray sources are detected in the present field of view, centered on the cluster core. The limiting sensitivity of our survey is approximately 6E-15 erg/s/cm^2 but clearly depends on the location in the field of view and on the source spectrum. Using different existing catalogues, over 85% of the X-ray sources could be associated with at least one optical and/or infrared counterpart within a limited cross-correlation radius of 2.5 or 3 arcsec according to the optical/IR catalogue used. The surface density distribution of the X-ray sources presents a slight N-S elongation. Once corrected for the spatial sensitivity variation of the EPIC instruments, the radial profile of the source surface density is well described by a King profile with a central density of about 8 sources per arcmin^2 and a core radius close to 3.1 arcmin. The distribution of the X-ray sources seems closely related to the optical source distribution. The expected number of foreground and background sources should represent about 9% of the detected sources, thus strongly suggesting that most of the observed X-ray emitters are physically belonging to NGC 6231. Finally, beside a few bright but soft objects -- corresponding to the early-type stars of the cluster -- most of the sources are relatively faint (~5E-15 erg/s/cm^2) with an energy distribution peaked around 1.0-2.0 keV. Description: The catalogue of the 610 X-ray sources detected in the 30'-diameter field of view of XMM-Newton is presented. Table 3 lists the equatorial coordinates, logarithmic likelihoods and count rates for the three EPIC instruments and for various energy ranges. Table 6 provides the cross-identification of the X-ray sources with various optical/infrared catalogues (2MASS, GSC2.2, USNO B1.0, SSB06) as well as with commonly used denominations (HD/HDE, CD, CPD, Segg., SBL98, Braes). Only the closest identification is reported here. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 16 54 12 -41 48.0 NGC 6231 = C 1650-417 ---------------------------------------------------------- File Summary: ------------------------------------------------------------------------------- FileName Lrecl Records Explanations ------------------------------------------------------------------------------- ReadMe 196 . This file table3.dat 610 47 X-ray source catalogue in NGC 6231 table6.dat 610 31 Cross-identification of the X-ray catalogue with different optical/IR catalogues ------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat ------------------------------------------------------------------------------- Bytes Format Units Label Explanations ------------------------------------------------------------------------------- 1- 3 I3 --- X# Internal X-ray source numbering scheme 6- 20 A15 --- XMMUJ Recommended XMM source denomination (1) 23- 27 F5.2 arcsec rAlpDel Error on the source position 30- 37 F8.1 --- L2(pn) pn: Equivalent likelihood L2 40- 46 F7.3 mCnt/s CR(pn) pn: count-rate in [0.5-10.0 keV] 48- 54 F7.3 mCnt/s rCR(pn) pn: error on CR [0.5-10.0 keV] 56- 62 F7.3 mCnt/s CR_s(pn) pn: count-rate in [0.5-1.0 keV] 64- 70 F7.3 mCnt/s rCR_s(pn) pn: error on CR_s [0.5-1.0 keV] 72- 78 F7.3 mCnt/s CR_m(pn) pn: count-rate in [1.0-2.5 keV] 80- 86 F7.3 mCnt/s rCR_m(pn) pn: error on CR_m [1.0-2.5 keV] 88- 94 F7.3 mCnt/s CR_h(pn) pn: count-rate in [2.5-10.0 keV] 96-102 F7.3 mCnt/s rCR_h(pn) pn: error on CR_m [2.5-10.0 keV] 104-110 F7.3 --- HR1(pn) pn: first hardness ratio (2) 112-118 F7.3 --- rHR1(pn) pn: error on HR1 120-126 F7.3 --- HR2(pn) pn: second hardness ratio (3) 128-134 F7.3 --- rHR2(pn) pn: error on HR2 137-144 F8.1 --- L2(m1) m1: Equivalent likelihood L2 147-153 F7.3 mCnt/s CR(m1) m1: count-rate in [0.5-10.0 keV] 155-161 F7.3 mCnt/s rCR(m1) m1: error on CR [0.5-10.0 keV] 163-169 F7.3 mCnt/s CR_s(m1) m1: count-rate in [0.5-1.0 keV] 171-177 F7.3 mCnt/s rCR_s(m1) m1: error on CR_s [0.5-1.0 keV] 179-185 F7.3 mCnt/s CR_m(m1) m1: count-rate in [1.0-2.5 keV] 187-193 F7.3 mCnt/s rCR_m(m1) m1: error on CR_m [1.0-2.5 keV] 195-201 F7.3 mCnt/s CR_h(m1) m1: count-rate in [2.5-10.0 keV] 203-209 F7.3 mCnt/s rCR_h(m1) m1: error on CR_m [2.5-10.0 keV] 211-217 F7.3 --- HR1(m1) m1: first hardness ratio (2) 219-225 F7.3 --- rHR1(m1) m1: error on HR1 227-233 F7.3 --- HR2(m1) m1: second hardness ratio (3) 235-241 F7.3 --- rHR2(m1) m1: error on HR2 244-251 F8.1 --- L2(m2) m2: equivalent likelihood L2 254-260 F7.3 mCnt/s CR(m2) m2: count-rate in [0.5-10.0 keV] 262-268 F7.3 mCnt/s rCR(m2) m2: error on CR [0.5-10.0 keV] 270-276 F7.3 mCnt/s CR_s(m2) m2: count-rate in [0.5-1.0 keV] 278-284 F7.3 mCnt/s rCR_s(m2) m2: error on CR_s [0.5-1.0 keV] 286-292 F7.3 mCnt/s CR_m(m2) m2: count-rate in [1.0-2.5 keV] 294-300 F7.3 mCnt/s rCR_m(m2) m2: error on CR_m [1.0-2.5 keV] 302-308 F7.3 mCnt/s CR_h(m2) m2: count-rate in [2.5-10.0 keV] 310-316 F7.3 mCnt/s rCR_h(m2) m2: error on CR_m [2.5-10.0 keV] 318-324 F7.3 --- HR1(m2) m2: first hardness ratio (2) 326-332 F7.3 --- rHR1(m2) m2: error on HR1 334-340 F7.3 --- HR2(m2) m2: second hardness ratio (3) 342-348 F7.3 --- rHR2(m2) m2: error on HR2 351-358 F8.3 --- L2(epic) epic: total equivalent likelihood L2 361-364 A4 --- Instr. used combination of instruments 367-369 A3 --- Ext. extended source flag 372-384 A13 --- Comment comments and warnings 387-395 F9.2 HMS.ss RA X-ray source RA (HHMMSS.ss) (4) 397-406 F9.1 dDMS.s DEC X-ray source Dec (dDDAMAS.s)(4) ------------------------------------------------------------------------------- Note (1): XMMUJ is the specified format for XMM-Newton source positions. It corresponds to the J2000 coordinates in format HHMMSS.sdDDAMAS. Note that the coordinates are truncated, not rounded. More accurate positions are given in the last two columns (Cols. 47 and 48) of the present table. Note (2): HR1 = (CR_m - CR_s) / (CR_m + CR_s) Note (3): HR2 = (CR_h - CR_m) / (CR_h + CR_m) Note (4): In order to avoid systematic shift, the coordinates have been rounded, not truncated. ------------------------------------------------------------------------------- Byte-by-byte Description of file: table6.dat ------------------------------------------------------------------------------- Bytes Format Units Label Explanations ------------------------------------------------------------------------------- 1- 3 I3 --- X# Internal X-ray source numbering scheme 6- 20 A15 --- XMMUJ Recommended XMM source denomination (1) 23- 27 F5.3 arcsec Dcc 2MASS: correlation distance 30- 45 A15 --- name 2MASS: source name 48- 53 F6.3 mag J 2MASS: J magnitude 56- 61 F6.3 mag H 2MASS: H magnitude 64- 69 F6.3 mag K 2MASS: K magnitude 72- 76 F5.3 arcsec Dcc GSC2.2: correlation distance 79- 92 A14 --- name GSC2.2: source name 95- 99 F5.2 mag R GSC2.2: R magnitude 102-106 F5.2 mag B GSC2.2: B magnitude 109-113 F5.2 mag V GSC2.2: V magnitude 116-120 F5.3 arcsec Dcc USNO B1.0: correlation distance 123-134 A12 --- name USNO B1.0: source name 137-141 F5.2 mag R1 USNO B1.0: R1 magnitude 144-148 F5.2 mag B1 USNO B1.0: B1 magnitude 151-155 F5.2 mag R2 USNO B1.0: R2 magnitude 158-162 F5.2 mag B2 USNO B1.0: B2 magnitude 165-169 F5.2 mag I USNO B1.0: I magnitude 172-176 F5.3 arcsec Dcc SSB06: correlation distance 179-179 A6 --- flag SSB06: flag (2) 180-184 A6 --- name SSB06: source name 187-192 F6.3 mag V SSB06: V magnitude 195-200 F6.3 mag V-I SSB06: V-I magnitude 203-208 F6.3 mag B-V SSB06: B-V magnitude 211-216 F6.3 mag U-B SSB06: U-B magnitude 219-224 I6 --- HD/HDE CI: HD/HDE number 227-231 I5 --- CD CI: CD number (in format CD-41°nnnnn) 234-237 I4 --- CPD CI: CPD number (in format CPD-41°nnnn) 240-242 I3 --- Segg. CI: Se number (3) 245-249 I5 --- SBL98 CI: SBL98 number (3) 252-255 I4 --- Braes CI: Braes number ------------------------------------------------------------------------------- Note (1): XMMUJ is the specified format for XMM-Newton source positions. It corresponds to the J2000 coordinates in format HHMMSS.sdDDAMAS. Note that the coordinates are truncated, not rounded. More accurate positions are given in the last two columns (Cols. 47 and 48) of Table 3. Note (2): An asterisk '*' means that the related stars were saturated in the SSB06 data set. Quoted photometric data are taken from SBL98. Note (3): In Simbad, Se NNN = NGC 6231 NNN SBL NNN = Cl* NGC 6231 SBL NNN ------------------------------------------------------------------------------- Acknowledgements: Hugues Sana Eric Gosset Gregor Rauw Hwankyung Sung Jean-Marie Vreux References: Braes L.L.E. 1967, Bull. Astr. Inst. Neth. Suppl., 2, 1 =1967BANS....2....1B GSC 2.2 2001, VizieR On-line Data Catalog: I/271 =2001yCat.1271....0S Seggewiss W. 1968, Veroeff. Astr. Inst. Univ. Bonn, 79, 1 =1968VeBon..79....1S SBL98: Sung H., Bessell M.S., Lee S.-W. 1998, ApJ, 115, 734=1998AJ....115..734S USNO B1.0: Monet D.G. et al. 2003, AJ, 125, 984 =2003AJ....125..984M 2MASS: Cutri R.M. et al. 2003, NASA/IPAC IR Sc. Archive =2003tmc..book.....C =============================================================================== (End) Sana [University of Liege / ESO ] 12-May-2006