[AAVSO-HEN] GRB 090618: Swift detection of a bright burst with optical afterglow

[Arto Oksanen]

A very bright optical afterglow! Arto

2009/6/18, grb at aavso.org <grb 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:  9512
> SUBJECT: GRB 090618: Swift detection of a bright burst with optical
> afterglow
> DATE:    09/06/18 08:48:39 GMT
> FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea at astro.psu.edu>
>
> P. Schady (MSSL-UCL), W. H. Baumgartner (GSFC/UMBC),
> A. P. Beardmore (U Leicester), S. Campana (INAF-OAB),
> P.A. Curran (MSSL-UCL), C. Guidorzi (U Ferrara), J. A. Kennea (PSU),
> J. Mao (INAF-OAB), R. Margutti (Univ Bicocca&OAB),
> J. P. Osborne (U Leicester), K. L. Page (U Leicester),
> P. Romano (INAF-IASFPA), M. H. Siegel (PSU), G. Stratta (ASDC) and
> T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
>
> At 08:28:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
> located GRB 090618 (trigger=355083).  Swift slewed immediately to the burst.
> The BAT on-board calculated location is
> RA, Dec 294.021, +78.353 which is
>    RA(J2000) = 19h 36m 05s
>    Dec(J2000) = +78d 21' 13"
> with an uncertainty of 3 arcmin (radius, 90% containment, including
> systematic uncertainty).  The BAT light curve showed multi peak
> structure with a duration of about 130 sec.  The peak count rate
> was ~40,000 counts/sec (15-350 keV), at 80 sec after the trigger.
>
> The XRT began observing the field at 08:30:30.8 UT, 120.9 seconds after
> the BAT trigger. XRT found a bright, uncatalogued X-ray source located
> at RA, Dec 293.9897, +78.3576 which is equivalent to:
>    RA(J2000)  = 19h 35m 57.52s
>    Dec(J2000) = +78d 21' 27.3"
> with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
> location is 28 arcseconds from the BAT onboard position, within the BAT
> error circle. No event data are yet available to determine the column
> density using X-ray spectroscopy.
>
> UVOT took a finding chart exposure of 150 seconds with the White
> filter  starting 128 seconds after the BAT trigger. There is a
> candidate afterglow in  the rapidly available 2.7'x2.7' sub-image at
>
>   RA(J2000)  =	19:35:58.69 = 293.99456
>   DEC(J2000) = +78:21:24.3  = 78.35676      with a 90%-confidence
> error radius of about 0.74 arc sec. This position   is 4.6  arc sec.
> from the center of the XRT error circle. The estimated   magnitude is
>  14.36 with  a 1-sigma error of about 0.01. No correction has   been
> made for the expected extinction corresponding to E(B-V) of 0.09.
>
> Burst Advocate for this burst is P. Schady (ps AT mssl.ucl.ac.uk).
> 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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-- 
Lähetetty matkaviestimestäni

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