[vsnet-grb-info 4620] GRB070506: Swift XRT refined analysis

Mon May 7 02:16:57 JST 2007

TITLE:   GCN CIRCULAR
NUMBER:  6377
SUBJECT: GRB070506: Swift XRT refined analysis
DATE:    07/05/06 17:16:51 GMT
FROM:    Claudio Pagani at PSU/Swift-XRT  <pagani at astro.psu.edu>

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C. Pagani, L. Vetere, J. L. Racusin and J. A. Kennea (PSU) report on  
behalf of the Swift Team:

We have analysed the first two orbits of Swift XRT data from GRB  
070506 (trigger number 278693, GCN Circ 6375.), for a total photon  
counting mode exposure of 2.8ks.
The XRT started collecting data in Image mode at 05:38:05 UT, 127  
seconds after the BAT trigger, but observations in Photon Counting  
mode were delayed due to the SAA, starting 432 seconds after the  
trigger. The refined XRT position from 2.8ks of PC data is
RA,DEC(J200) = 347.2179, +10.7217
which is
RA(J2000) = 23d 08m 52.30s
DEC(J200) = +10d 43' 18.2"

with an uncertainty of 5.4 arcsec (radius, 90% containment).
This is  5.1 arcsec from the initial X-ray position and 2.4 arcsec  
from the UVOT optical counterpart (GCN 6375).

The XRT light curve created from the first two orbits of PC data  
reveals a decaying source with hints of flaring activity. A power law  
fit yields a decay slope of 0.55+/-0.06.

The X-ray spectrum of the PC data, modeled with an absorbed power law  
gives a photon index of 2.5+/-0.5 and a total column density of NH= 
(1.8+/-1.1)e21 cm**-2, in excess of the Galactic value of 0.4e21 cm**-2.
The absorbed (unabsorbed) 0.3-10.0keV flux for this spectrum was  
3.0E-12 (5.5E-12) ergs cm^-2 s^-1.

Assuming the source continues to decay at the same rate, we predict  
an XRT count rate of 2.2e-2 count/s at T+24 hours, which corresponds  
to an observed (unabsorbed) flux of 0.8E-12 (1.5E-12) ergs cm^-2 s^-1.

This circular is an official product of the Swift XRT team.
--Apple-Mail-8-448627958
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<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; =
-khtml-line-break: after-white-space; "><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">C. Pagani,=A0L.=
 Vetere, J. L. Racusin and J. A. Kennea (PSU)=A0report on behalf of the =
Swift Team:</DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; "><BR =
class=3D"khtml-block-placeholder"></DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">We have =
analysed the first two orbits of Swift XRT data from=A0GRB 070506 =
(trigger number 278693, GCN Circ 6375.), for a total photon counting =
mode exposure of 2.8ks.=A0</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The XRT =
started collecting data in Image mode=A0at 05:38:05 UT, 127 seconds =
after=A0the BAT trigger, but observations in Photon Counting mode were =
delayed due to the SAA, starting 432 seconds after the trigger. The =
refined XRT position from 2.8ks of PC data is</DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><FONT class=3D"Apple-style-span" face=3D"Monaco" =
size=3D"3"><SPAN class=3D"Apple-style-span" style=3D"font-size: =
11px;">RA,DEC(J200) =3D 347.2179, +10.7217</SPAN></FONT></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; "><FONT class=3D"Apple-style-span" face=3D"Monaco" =
size=3D"3"><SPAN class=3D"Apple-style-span" style=3D"font-size: =
11px;">which is</SPAN></FONT></DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT =
class=3D"Apple-style-span" face=3D"Monaco" size=3D"3"><SPAN =
class=3D"Apple-style-span" style=3D"font-size: 11px;">RA(J2000) =3D=A023d =
08m 52.30s</SPAN></FONT></DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT =
class=3D"Apple-style-span" face=3D"Monaco" size=3D"3"><SPAN =
class=3D"Apple-style-span" style=3D"font-size: 11px;">DEC(J200) =3D=A0+10d=
 43' 18.2"</SPAN></FONT></DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal =
normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">with an uncertainty of 5.4 arcsec (radius, 90% =
containment).</DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; ">This is=A0 5.1=A0arcsec=A0from =
the initial X-ray position and 2.4 arcsec from the UVOT optical =
counterpart (GCN 6375).</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal =
normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">The=A0XRT light curve created from the first two =
orbits of PC data=A0reveals a decaying source with hints of flaring =
activity. A power law=A0fit yields a decay slope of =
0.55+/-0.06.</DIV><DIV style=3D"margin-top: 0px; margin-right: 0px; =
margin-bottom: 0px; margin-left: 0px; font: normal normal normal =
12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">The X-ray spectrum of the PC data,=A0modeled with an =
absorbed power law=A0gives a photon index of 2.5+/-0.5=A0and a total =
column density of=A0NH=3D(1.8+/-1.1)e21 cm**-2, in excess of the =
Galactic value of 0.4e21 cm**-2.</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The =
absorbed=A0(unabsorbed) 0.3-10.0keV flux for this spectrum was 3.0E-12 =
(5.5E-12)=A0ergs cm^-2 s^-1.</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal =
normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">Assuming the source continues to decay at the same =
rate, we predict an=A0XRT count rate of 2.2e-2 count/s at T+24 hours, =
which corresponds to an=A0observed (unabsorbed) flux of 0.8E-12 =
(1.5E-12) ergs cm^-2 s^-1.</DIV><DIV style=3D"margin-top: 0px; =
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal =
normal normal 12px/normal Helvetica; min-height: 14px; "><BR></DIV><DIV =
style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">This circular is an official product of the Swift =
XRT team.</DIV></BODY></HTML>=

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