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J/AJ/133/1027      Positions for 179 Swift X-ray afterglows  (Butler+, 2007)
Refined astrometry and positions for 179 Swift X-ray afterglows.
    Butler N.R.
   <Astron. J., 133, 1027-1033 (2007)>
   =2007AJ....133.1027B
ADC_Keywords: Gamma rays ; Positional data

Keywords: gamma rays: bursts - supernovae: general - telescopes -
          X-rays: general

Abstract:
    We present a refined catalog for the positions of 179 gamma-ray burst
    (GRB) X-ray afterglows observed by the X-Ray Telescope (XRT) on Swift
    prior to 2006 November 1. The positions are determined by detecting
    X-ray field sources in the deep X-ray images and comparing the
    centroids to those of optical sources in the Digitized Sky Survey red2
    catalog or the Sloan Digital Sky Survey Data Release 5 catalog. Half
    of the 90% confidence error region radii are <2.2". The error regions
    areas are typically ∼4 times smaller than the best XRT team error
    regions, although the positions require deep X-ray integration (>20ks)
    and cannot be generated nearly as rapidly after the GRB. The positions
    derived for >90% of 77 bursts with optical afterglows are consistent
    with the optical transient positions, without the need for systematic
    error. About 20% of the afterglow positions require a sizable shift in
    the Swift satellite aspect. We discuss the optical/X-ray properties of
    the field sources and discuss the implications of the frame offsets
    for studies of optically dark GRBs.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        43      179   Refined XRT GRB Afterglow Positions


See also:
          X/20  : The Fourth BATSE Burst Revised Catalog (Paciesas+ 1999)
         II/282 : The SDSS Photometric Catalog, DR6 (Adelman-McCarthy+, 2007)
  J/A+A/455/813 : BeppoSAX catalog of GRB X-ray afterglows (De Pasquale+, 2006)
  J/A+A/473/347 : BeppoSAX complete catalogue of GRBs (Vetere+, 2007)
  J/A+A/448/L9  : Position catalogue of Swift XRT afterglows (Moretti+, 2006)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1-  7  A7    ---     GRB       GRB identification
   9- 10  I2    ---     n_GRB     ? Number in Fig.3 (1)
  12- 13  I2    h       RAh       Hour of Right Ascension (J2000)
  15- 16  I2    min     RAm       Minute of Right Ascension (J2000)
  18- 22  F5.2  s       RAs       Second of Right Ascension (J2000)
      24  A1    ---     DE-       Sign of the Declination (J2000)
  25- 26  I2    deg     DEd       Degree of Declination (J2000)
  28- 29  I2    arcmin  DEm       Arcminute of Declination (J2000)
  31- 34  F4.1  arcsec  DEs       Arcsecond of Declination (J2000)
      36  A1    ---     Off       [o] Indicates position lying outside the
                                      refined XRT-Team error region
  38- 41  F4.1  arcsec  Err90     The 90% confidence error region radius
      43  A1    ---     n_Err90   [ab] Matching optical catalog (2)

Note (1): Number refers to Figure 3 and denotes a burst with an
     optical transient (OT) position.
Note (2): Flag as follows:
      a = Position matching with SDSS DR-5 catalog
      b = Position matching with DSS-red2 catalog


History:
    From electronic version of the journal
(End)                  Greg Schwarz [AAS], Patricia Vannier [CDS]    09-Jan-2009