GRB 130603A

A. Melandri (INAF-OAB), C. Gronwall (PSU),
C. B. Markwardt (NASA/GSFC), D. M. Palmer (LANL) and T. Sakamoto (AGU)
report on behalf of the Swift Team:

At 05:59:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130603A (trigger=557274).  Swift could not immediately slew
to the burst due to an Earth limb constraint. 
The BAT on-board calculated location is 
RA, Dec 86.954, +82.934 which is 
   RA(J2000) = 05h 47m 49s
   Dec(J2000) = +82d 56' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single
FRED structure with a duration of about 100 sec.  The peak count rate
was ~1275 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+49.7
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is A. Melandri (andrea.melandri 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.)

A. Melandri (INAF/OAB) reports on behalf of the Swift team:

Swift-XRT observed the field of GRB 130603A (Melandri et al., GCN  
Circ. 14731
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 ) starting at T0+49.7 minutes due to an observing  
constraint. Using promptly downlinked data we find an uncatalogued X- 
ray source located at RA, Dec = 86.8938, 82.9099 which is equivalent to:

RA  (J2000.0) =  05 47 34.51
DEC (J2000.0) =  +82 54 35.7

with an uncertainty of 3.7 arcsec (radius, 90% containment).

A source is also detected by Swift-UVOT located at RA, Dec = 86.8914,  
82.9087 which is equivalent to

RA  (J2000.0) =  05 47 33.9
DEC (J2000.0) =  +82 54 31.3

with an uncertainty of 0.8 arcsec (radius, 90% containment).

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).

D.N. Burrows (PSU), J.A. Kennea (PSU), M. Perri (ASDC), G. Tagliaferri
(INAF-OAB), P.A. Evans (U. Leicester) and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 130603A at 06:51:16.2 UT,
3103.6 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 86.89380, 82.90992
which is equivalent to:
   RA(J2000)  = 05h 47m 34.51s
   Dec(J2000) = +82d 54' 35.7"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 90 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 (5.28 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 4.9
(+2.95/-2.45) x 10^21 cm^-2 (90% confidence).

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130603A (Melandri et al., GCNC 14731)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2013-06-03 11:14:06 UT (~5.2 h after the burst).
We detected the previously reported afterglow (Melandri, GCNC 14732)
in all the three bands.

Photometric results of the OT are listed below.
We used SDSS catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'  g'_err   Rc  Rc_err   Ic  Ic_err
-----------------------------------------------------------------------
0.22890    11:29:09    1560.0    18.3  0.3    18.4  0.2    18.1  0.3
0.24993    11:59:26    1500.0    18.9  0.3    18.8  0.2    18.2  0.3
------------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
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 recent telemetry downlinks,
we report further analysis of BAT GRB 130603A (trigger #557274)
(Melandri, et al., GCN Circ. 14731
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 ).  The BAT ground-calculated position is
RA, Dec = 86.859, 82.910 deg, which is 
   RA(J2000)  =  05h 47m 26.1s 
   Dec(J2000) = +82d 54' 36.7" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.
 
The mask-weighted light curve shows mostly smooth peak starting at ~T-10 sec,
peaking at ~T+11 sec, and ending at ~T+115 sec.
T90 (15-350 keV) is 76 +- 19 sec (estimated error including systematics).
 
The time-averaged spectrum from T-19.5 to T+104.5 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.83 +- 0.12.  The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+11.27 sec in the 15-150 keV band
is 0.8 +- 0.1 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/557274/BA/

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

Using 4017 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 130603A, 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 = 86.89660, +82.90853 which is equivalent
to:

RA (J2000): 05h 47m 35.18s
Dec (J2000): +82d 54' 30.7"

with an uncertainty of 1.5 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.

M. De Pasquale (MSSL/UCL) and A. Melandri (INAF/OAB) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130603A
3325 s after the BAT trigger (Melandri et al., GCN Circ. 14731
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 ). The
uncatalogued source reported in Melandri et al., GCN Circ. 14732
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 , is
detected in the summed exposures.

Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the summed exposures are:

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

white         3686       5322       393       19.61 � 0.15
v             4097       5562       197      >19.02
b             3481      16641      1278       19.71 � 0.15
u             3275      15729      1278       19.19 � 0.13
uvw1          4507       4707       197       19.62 � 0.39 (2.8 sigma)
uvm2          4302       4502       197      >19.63
uvw2          3892       5528       393       20.25 � 0.37 (2.8 sigma)

The possible detection of the optical source in uw2 filter indicates
a redshift z < ~1.5 for this event.

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.06 in the direction of
the burst (Schlegel et al. 1998).

A. Melandri (INAF-OAB) reports on behalf of the Swift-XRT team:

We have analysed 13 ks of XRT data for GRB 130603A (Melandri  et al.
GCN Circ. 14731
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 ),  from 3.1 ks to 34.3 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Beardmore et al. (GCN. Circ
14737).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.52 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.32 (+0.18, -0.17). The
best-fitting absorption column is  4.7 (+0.8, -0.7) x 10^21 cm^-2, in
excess of the Galactic value of 5.3 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.8 x 10^-11 (8.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     4.7 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 5.3 x 10^20 cm^-2
Excess significance: 9.9 sigma
Photon index:	     2.32 (+0.18, -0.17)

If the light curve continues to decay with a power-law decay index of
0.52, the count rate at T+24 hours will be 0.028 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-12 (2.4 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00557274.

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

P. Kehusmaa, A. Oksanen and C. Harlingten report on behalf of 
the Searchlight Observatory Network:

On 2013 June 03, starting at 06:42 UT (T0+42.5 minutes), we observed 
the field of GRB130603A (Melandri et al., GCN Circ. 14731
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 ) with 
the 0.40 m NM1 telescope located in New Mexico, USA with Apogee Alta 
U42 CCD for 3x120 seconds using the V filter and 7x120 seconds unfiltered. 
The afterglow reported by Melandri et. al. (GCNC 14732) is detected in 
all unfiltered images and in the coadded V band image.
 
We report following differental photometry:

UTC (mid)            T0+(h)    Mag     Err   Filter
----------------------------------------------------------
2013-06-03T06:44:21  0.75      18.78   0.13  V 
2013-06-03T06:59:55  1.00      18.79   0.07  clear
----------------------------------------------------------

The reference magnitude from the nearby USNO B1.0 star (1729-0016610) 
with R=16.49.

A snapshot showing our coadded unfiltered image can be found at the URL
http://pilvi.dyndns.org/arto/GRB130603A_C_840s.jpg

K. Ito, Y. Saito, Y. Yano, R. Usui, Y. Tachibana, T. Yoshii,
S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 130603A (Melandri et al., GCNC 14731) with the 
optical three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope of Akeno Observatory, Yamanashi, Japan.

The observation started on 2013-06-03 10:10:04 UT ( ~4.2 h after
the burst). And we could not find any new point source within the XRT
error circle (Beardmore et al., GCNC 14737) in all the three bands.

The results of photometry (3 sigma upper limits) are listed below.
We used GSC2.3 catalog for flux calibration.


T0+[hour]     MID-UT   T-EXP[sec]             g'             Rc                Ic
--------------------------------------------------------------------------------------------
       4.175   12:30:14              9054      >19.4        >19.4        >18.7
--------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst [hour]
T-EXP: Total Exposure time [sec]

A. Volnova (IKI), R.Inasaridze (AAO), O. Kvaratskhelia (AAO), V. 
Ayvazian(AAO), Yu. Krugly (IA KhNU),  I. Molotov (KIAM), A. Pozanenko 
(IKI)  report on behalf of  larger GRB follow-up collaboration:

We observed the field of the Swift Swift GRB 130603A (Melandri et al., 
GCN 14731
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 )with AS-32 (0.7m) telescope of Abastumani Observatory  on Jun. 
03 and Jun. 04. We obtained several unfiltered images of 300 s and 180 s 
exposures. The afterglow (Melandri  et al., GCN 14732
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 ) is well detected 
in  combined images in both epochs. Preliminary photometry

Date        T_start    t-t0,      exp,    OT
             (UT)       mid, d     s
2013-06-03  22:19:06   0.69976    9x300   20.30 +/- 0.09
2013-06-04  20:28:49   1.62003   13x180   21.60 +/- 0.19

is based on SDSS stars R mag, where R mag obtained via transformations 
ugriz in BVRI (Lupton, 2005):

n SDSS                  R     errR
1 J054806.91+825053.0  17.648 0.015
2 J054805.54+825456.1  16.750 0.013
3 J054706.99+825234.5  15.573 0.012