[AAVSO-HEN] slowly fading afterglow?

[Arto Oksanen]

Early reports state that this afterglow did not fade as fast as they
usually do. It may still be detectable by amateur telescopes.

Location is between Ursa Major and Leo.

arto

---------- Forwarded message ----------
From: grb at aavso.org <grb at aavso.org>
Date: 30.3.2008 6:10
Subject: [AAVSO-HEN] GRB 080330: Swift detection of a burst with an
optical counterpart
To: aavso-hen at aavso.org



 The following is a GCN Circular circulated via the AAVSO network.
 For an archive and more information on circulars visit:
 http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

 TITLE:   GCN CIRCULAR
 NUMBER:  7537
 SUBJECT: GRB 080330: Swift detection of a burst with an optical counterpart
 DATE:    08/03/30 04:02:22 GMT
 FROM:    David Palmer at LANL  <palmer at lanl.gov>

 J. Mao (INAF-OAB), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
 N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),
 J. A. Kennea (PSU), K. M. McLean (GSFC/UMD), D. M. Palmer (LANL),
 A. M. Parsons (GSFC), M. Stamatikos (NASA/ORAU),
 R. L. C. Starling (U Leicester), T. N. Ukwatta (GSFC/GWU) and
 D. E. Vanden Berk (PSU) report on behalf of the Swift Team:

 At 03:41:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
 located GRB 080330 (trigger=308041).  Swift slewed immediately to the burst.
 The BAT on-board calculated location is
 RA, Dec 169.302, +30.570 which is
   RA(J2000) = 11h 17m 12s
   Dec(J2000) = +30d 34' 13"
 with an uncertainty of 3 arcmin (radius, 90% containment, including
 systematic uncertainty).  The BAT light curve showed a multiple-peak
 structure with a duration of about 60 sec.  The peak count rate
 was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.


 The XRT began observing the field at 03:42:27.4 UT, 70.5 seconds after
 the BAT trigger. Using promptly downlinked data we find a bright,
 fading, uncatalogued X-ray source located at RA, Dec 169.26095,
 30.62298 which is equivalent to:
   RA(J2000)  = 11h 17m 2.63s
   Dec(J2000) = +30d 37' 22.7"
 with an uncertainty of 3.077 arcseconds (radius, 90% containment). This
 location is 229 arcseconds from the BAT onboard position, outside the
 BAT error circle.

 A power-law fit to a spectrum formed from promptly downlinked event
 data does not constrain the column density, so we cannot provide limits
 on the redshift using spectroscopy and the relation from Grupe et al.
 (2007). A summary of the promptly downlinked data is given at
 http://www.swift.ac.uk/sper/308041/.

 The initial flux in the 2.5 s image was 2.03e-09 erg cm^-2 s^-1 (0.2-10
 keV).


 UVOT took a finding chart exposure of nominal 100 seconds with the White
 (160-650 nm) filter starting 82 seconds after the BAT trigger. There is a
 candidate afterglow in the list of sources generated on-board at
  RA(J2000)  =  11:17:04.51 = 169.2688
  DEC(J2000) = +30:37:22.1  =  30.6228
 with a 1-sigma error radius of about 1.0 arc sec. This position is 6.1 arc sec.
 from the center of the XRT error circle. The estimated magnitude is 18.8 with a
 1-sigma error of about 0.5 mag. No correction has been made for the expected
 extinction corresponding to E(B-V) of 0.02.




 Burst Advocate for this burst is J. Mao (jirong.mao AT brera.inaf.it).
 Please contact the BA by email if you require additional information
 regarding Swift followup of this burst. In extremely urgent cases, after
 trying the Burst Advocate, you can contact the Swift PI by phone (see
 Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

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-- 
Arto Oksanen
arto.oksanen at jklsirius.fi
Muurame, Finland