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J/ApJ/678/102       BAT X-ray survey. I.                     (Ajello+, 2008)

BAT X-ray survey. I. Methodology and X-ray identification. Ajello M., Greiner J., Kanbach G., Rau A., Strong A.W., Kennea J.A. <Astrophys. J., 678, 102-115 (2008)> =2008ApJ...678..102A
ADC_Keywords: Surveys ; X-ray sources ; Active gal. nuclei ; Gamma ray Mission_Name: Swift Keywords: galaxies: active - surveys - X-rays: binaries - X-rays: galaxies Abstract: We applied the maximum likelihood (ML) method, as an image reconstruction algorithm, to the BAT (Burst Alert Telescope) X-Ray Survey (BXS). This method was specifically designed to preserve the full statistical information in the data and to avoid mosaicking of many exposures with different pointing directions, thus reducing systematic errors when co-adding images. We reconstructed, in the 14-170keV energy band, the image of a 90x90deg2 sky region, centered on (RA, DE)=(105°, -25°), which BAT surveyed with an exposure time of ∼1Ms (in 2005 November). The best sensitivity in our image is ∼0.85mCrab or 2.0x10-11ergs/cm2. We detect 49 hard X-ray sources above the 4.5σ level; of these, only 12 were previously known as hard X-ray sources (>15keV). Swift XRT observations allowed us to firmly identify the counterparts for 15 objects, while 2 objects have Einstein IPC counterparts (Harris et al., 1990, in Imaging X-Ray Astronomy. A Decade of Achievements, ed. M. Elvis (Cambridge: Cambridge Univ. Press), 309); in addition to those, we found a likely counterpart for 13 objects by correlating our sample with the ROSAT All-Sky Survey Bright Source Catalog (Voges et al., 1999, Cat. IX/10). Seven objects remain unidentified. Description: We used 8 months of data, from 2005 April (when BAT data became public) to 2005 November. In order to secure optical follow-up with a dedicated observing campaign at La Silla, Chile, in 2006 January, we selected only observations with angular separation less than 45° from the zenith (RA, DE)=(105°, -25°). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 114 45 Detected hard X-ray sources
See also: J/ApJ/633/L77 : SWIFT/BAT detections of AGN (Markwardt+, 2005) J/ApJ/673/96 : BAT X-ray Survey - III (Ajello+, 2008) J/ApJ/681/113 : a faire Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 12 A12 --- SWIFT Swift identification (JHHMM.m+DDMM) 14- 21 F8.4 deg RAdeg Right Ascension in degrees (J2000) 23- 30 F8.4 deg DEdeg Declination in degrees (J2000) 32- 36 F5.2 10-14W/m2 Flux Observed flux (14-170keV) (10-11erg/cm2/s) 38- 42 F5.2 --- S/N Signal-to-Noise ratio 44- 46 I3 100ks Exp Exposure time 48- 65 A18 --- OID Counterpart identification 67 A1 --- f_OID [b] Source identified from ROSAT (1) 69- 71 F3.1 arcmin Off ? Offset from Swift and other identification positions 73- 79 A7 --- Type Source type 81- 87 A7 --- Cat Catalog/Instrument used for identification (2) 89 A1 --- n_Cat [cde] Notes about associations (3) 91- 92 I2 h RAXh ? X-ray telescope (XRT) Right Ascension (J2000) 94- 95 I2 min RAXm ? X-ray telescope (XRT) Right Ascension (J2000) 97-100 F4.1 s RAXs ? X-ray telescope (XRT) Right Ascension (J2000) 102 A1 --- DEX- X-ray telescope (XRT) Declination sign (J2000) 103-104 I2 deg DEXd ? X-ray telescope (XRT) Declination (J2000) 106-107 I2 arcmin DEXm ? X-ray telescope (XRT) Declination (J2000) 109-112 F4.1 arcsec DEXs ? X-ray telescope (XRT) Declination (J2000) 114 A1 --- Ref Reference code for XRT position (4)
Note (1): b = Source identified thanks to its proximity to a ROSAT Bright Source (Cat. IX/10) with the method described in the text Note (2): Sources are abbreviated as follows: R = ROSAT catalog I = INTEGRAL catalog H = HEAO-1 catalog E = Einstein IPC catalog X = X-ray telescope onbard Swifth observations Note (3): Flag on Cat as follows: c = 3C 227 was detected in a long (11ks) ROSAT-PSPC observations (Crawford & Fabian, 1995MNRAS.273..827C) d = Source J0811.5+0937 has a ROSAT counterpart, 1WGA J0811.5+0933, reported in the WGA catalog (White et al., 1994BAAS...26.1372W). This source coincides with RX J081132.4+093403. e = Object has a ROSAT source in the error box, however the association has to be proven. Note (4): Reference code as follows: 1 = Tueller et al. (2005ATel..668....1T, 2005ATel..669....1T) 2 = Kennea et al. (2005ATel..677....1K) 3 = Ajello et al. (2006ATel..697....1A)
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 18-Sep-2009
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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