GRB 130625A

D. Grupe (PSU), V. D'Elia (ASDC), P. A. Evans (U Leicester),
A. Y. Lien (NASA/GSFC/ORAU) and K. L. Page (U Leicester) report on
behalf of the Swift Team:

At 07:00:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130625A (trigger=558982).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 343.268, +82.178 which is 
   RA(J2000) = 22h 53m 04s
   Dec(J2000) = +82d 10' 42"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peak
structure with a duration of about 30 sec.  The peak count rate
was ~1648 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 07:02:16.7 UT, 97.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 343.2798,
82.1734 which is equivalent to:
   RA(J2000)  = 22h 53m 07.15s
   Dec(J2000) = +82d 10' 24.1"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 17 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.06 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 2.8
(+2.84/-2.37) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 102 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.22. 

Burst Advocate for this burst is D. Grupe (dxg35 AT psu.edu). 
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.)

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1226 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130625A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 343.27789, +82.17438 which is equivalent
to:

RA (J2000): 22h 53m 6.69s
Dec (J2000): +82d 10' 27.8"

with an uncertainty of 2.2 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), D. Grupe (PSU),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC),
T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130625A (trigger #558982)
(Grupe, et al., GCN Circ. 14923
Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 343.336, 82.171 deg, which is 
   RA(J2000)  =  22h 53m 20.6s 
   Dec(J2000) = +82d 10' 17.1" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.
 
The mask-weighted light curve shows two overlapping peaks starting at ~T-25sec,
peaking at ~T+3 sec, and ending at ~T+60 sec.  T90 (15-350 keV) is
38.1 +- 4.9 sec (estimated error including systematics).
 
The time-averaged spectrum from T-28.17 to T+18.50 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.37 +- 0.09.  The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.54 sec in the 15-150 keV band
is 1.2 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/558982/BA/

D. Xu (DARK/NBI), A. Esamdin, L. Ma, C.-H. Bai, G.-J. Feng (XAO) report:

We observed the field of GRB 130625A (Grupe et al., GCN 14923
Loading...
 
 ) using
the 1m telescope located at Mt. Nanshan, Xinjiang Astronomical
Observatory, China. We obtained 6x300s R-band frames with a mean time
of 15:40:08 UT on 2013-06-25, (i.e., 8.658 hr after the burst).

No optical source is detected within the enhanced XRT error circle
(Goad et al., GCN 14924
Loading...
 
 ) in the stacked image, down to a limit
magnitude of R=21.0 mag, calibrated with the USNO B1 catalog.

J. S. Linevsky (PSU/CBHS), M. H. Siegel (PSU), and
D. Grupe (PSU)  report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130625A
102 s after the BAT trigger (Grupe et al., GCN Circ. 14923
Loading...
 
 ).
No optical afterglow consistent with the enhanced XRT position
(Grupe et al. GCN Circ. 14924
Loading...
 
 ) is detected in the initial UVOT exposures.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter  T_start(s)  T_stop(s)  Exp(s)  Mag 

white_FC    102      252       147    >20.96  
white       595     1890       283    >21.34 
v           644     1940       155    >19.34   
b           570     1866       136    >20.21  
u_FC        315      565       245    >20.26  
u           315     2003       617    >20.81 
uvw1        694     1989       136    >19.60     
uvm2        844     6816       332    >20.04  
uvw2        620     1916       155    >19.79   

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.22 in the direction of the burst
(Schlegel et al. 1998).

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk

  E. Gorbovskoy, V. Lipunov, D.Denisenko, V.Kornilov, 
D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, 
V.V.Chazov
Sternberg Astronomical Institute, Lomonosov Moscow State University


K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University, Irkutsk


A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)



MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Blagoveschensk was pointed to the  GRB130625A 23177 sec s after 
notice time and 23214 sec after GRB time at 2013-06-25 13:27:34.231 UT. On 
our first (180s exposure) set we haven`t found optical transient  within 
Swift error-box (D. Grupe et al. GCN 14923
Loading...
 
 ).
The 5-sigma upper limit has been about 17.5 mag

On coadd images  images we received the following limits


  T_start  T_finish  T_mid      t_mid-t_grb  Exptime   Filter   Limit  Coadd
---------------------------------------------------------------------------
13:27:34  14:17:44  13:52:39   24719 s      2700 s       R      19.0     15
13:31:38  14:17:44  13:54:41   24841 s      2520 s       W      19.5     14

The message may be cited.

J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), V.
D'Elia (ASDC), A. Maselli  (INAF-IASFPA), V. Mangano (INAF-IASFPA) and
D. Grupe report on behalf of the Swift-XRT team:

We have analysed 2.8 ks of XRT data for GRB 130625A (Grupe  et al. GCN
Circ. 14923
Loading...
 
 ),  from 100 s to 25.1 ks after the	BAT trigger. The data
comprise 34 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Goad et al. (GCN. Circ 14924).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.70 (+0.21, -0.23).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+0.7, -0.6). The
best-fitting absorption column is  4.8 (+3.3, -2.3) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.1 x 10^-11 (8.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     4.8 (+3.3, -2.3) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 2.6 sigma
Photon index:	     2.2 (+0.7, -0.6)

If the light curve continues to decay with a power-law decay index of
1.70, the count rate at T+24 hours will be 5.3 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x
10^-15 (4.4 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00558982.

This circular is an official product of the Swift-XRT team.