GRB 130502A

E. Troja (NASA/GSFC/UMCP), A. A. Breeveld (UCL-MSSL),
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
S. T. Holland (STScI), H. A. Krimm (CRESST/GSFC/USRA),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU),
M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. C. Stroh (PSU),
C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the
Swift Team:

At 17:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130502A (trigger=554996).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 138.578, -0.143 which is 
   RA(J2000) = 09h 14m 19s
   Dec(J2000) = -00d 08' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 5 sec.  The rapidly available light
curve also shows a peak in the lowest energy at T+10 sec, but it is
not clear at this time whether or not the second peak is real. The 
peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after 
the trigger. 

The XRT began observing the field at 17:52:01.8 UT, 91.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 138.5690, -0.1232 which
is equivalent to:
   RA(J2000)  = 09h 14m 16.56s
   Dec(J2000) = -00d 07' 23.7"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 78 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 (2.49 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5
(+1.77/-1.57) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 95 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
0.03. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
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.)

T.  Guver  (Sabanci  Univ.),  B.  Ozcan  (Adiyaman  Univ.)  E.  Sonbas
(Adiyaman  Univ.),   M.  Kocak   (TUG),  E.  Gogus   (Sabanci  Univ.),
H. Kirbiyik (TUG) report on behalf of a larger collaboration

We observed  the field of Swift  GRB 130502A (Troja  et al. GCN#14527
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 )
with  the  1.0 meter  T100  telescope  (TUBITAK National  Observatory,
Antalya - Turkey),  starting May, 02, 18:17:41 UT  (~ 27 minutes after
the trigger). Observations were carried out in the R filter under good
weather conditions.

We do  not detect an optical  afterglow within the  reported XRT error
circle down to  a limiting magnitude of 20.8 in the  R band. Our image
is calibrated  using USNO A2.0 R1 magnitude of the star at  RA :
135.578498, DEC : -00.149362 (J2000).

We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their technical support.

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D. Malesani (DARK/NBI), P. D'Avanzo (INAF/OABr), M. Cecconi (INAF/FGG), 
C. P. Padilla-Torres (INAF/FGG), report on behalf of the CIBO collaboration:

We observed the field of GRB 130502A (Troja et al., GCN 14527
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 ) with the 
TNG equipped with DOLoRes. A 10-minute image in the SDSS r filer was 
taken starting on May 2.872 UT (3.08 hr after the GRB trigger).

Close to the edge of the current XRT error circle (see 
http://www.swift.ac.uk/xrt_positions/), we detect a faint object, with 
coordinates (J2000):

RA = 09:14:16.42
Dec = -00:07:23.0

The object has r = 23.49 +- 0.16 AB, calibrated against nearby SDSS DR8 
stars.

At the present time, we cannot assess the variability of the target, nor 
its relation with GRB 130502A. Further observations are planned.

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J. Gorosabel (UPV/EHU, IAA-CSIC), 
N. Tanvir (U. Leicester), J. P. U. Fynbo (DARK/NBI), A. Cabrera-Lavers (IAC-ULL), 
and C.C. Thoene (IAA-CSIC) report:

We observed the afterglow of GRB 130502A (Troja et al. GCN 14527
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 ) 
with the 10.4m GTC telescope starting at 21:01 UT (3.18 hrs after the burst). 
The observation had a total exposure time of 340 s in z-band. The object 
reported by Malesani et al. GCN 14531
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  is detected with an AB magnitude of 
22.6+/-0.15 as compared to stars in the SDSS DR9 catalogue.

J. Gorosabel (IAA-CSIC/UPV-EHU), A. de Ugarte Postigo (IAA-CSIC/DARK-NBI),
J.C. Tello (IAA-CSIC),  A.J. Castro-Tirado (IAA-CSIC), J. Cepa (IAC), D.
Jimenez-Mejias (IAC), R. Alonso (IAC), R. Sanchez-Ramirez (IAA-CSIC), V.
Casanova (IAA-CSIC), report on behalf of a larger collaboration:

We observed the GRB 130502A (Troja et al. GCN 14527
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 ) optical afterglow
(Malesani et al. GCN 14531
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 ; de Ugarte Postigo et al. GCN 14533
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 ) in I-band
with both the 1.5m OSN and 0.82m IAC80 telescopes as follows;

  Tel.  Hr post-GRB  Texp  Vega(Mag)
 -------------------------------------
 OSN    3.13-3.71  10x200s  > 22.0
 IAC80  3.43-5.14  16x300s 22.75+/-0.35
 -------------------------------------

calibrated against the USNO B1.0 catalogue.

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

Using 511 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130502A, 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 = 138.56888, -0.12341 which is equivalent
to:

RA (J2000): 09h 14m 16.53s
Dec (J2000): -00d 07' 24.3"

with an uncertainty of 1.8 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.

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),
Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130502A (Troja, et al., GCN 14527
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 ) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir from 2013/05 3.14 to 2013/05 3.17 UTC (9.48 to
10.34 hours after the BAT trigger), obtaining a total of 0.71 hours
exposure in the r' and i' bands and 0.30 hours exposure in the Z, Y, J, and
H bands.

For a source within the Swift-XRT error circle (Beardmore, et al., GCN
14536
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 ), in comparison with SDSS DR8 and 2MASS, we obtain the following
upper limits (3-sigma):

  r'    > 22.82
  i'    > 22.66
  Z    > 21.65
  Y    > 21.45
  J    > 21.16
  H    > 20.99

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.

A. A. Breeveld (MSSL-UCL) and E. Troja (NASA/GSFC/UMCP) report on behalf 
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130502A 96 
s after the BAT trigger (Troja et al., GCN Circ. 14527
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 ).
An optical afterglow consistent with the position of the TNG candidate 
(Malesani et al. GCN Circ. 14531
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 ) is detected in the initial white 
exposure. Preliminary magnitude and 3-sigma upper limits using the UVOT 
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for 
the first white finding chart (FC) exposure and subsequent exposures are:

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

white_FC         96         246          147        20.90 � 0.3
white           588         608           20        >20.06
u               309         559          246        >20.6
b               564         584           20        >19.25
v              5288        5488          197        >19.81
uvw1           5698        5898          197        >20.16
uvm2           5492        5692          197        >19.96

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.03 in the direction of the 
burst (Schlegel et al. 1998).

G. Younes (NASA/USRA) reports on behalf of the Fermi GBM Team:

"At 17:50:30.74 UT on May 2 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130502A (trigger 389209833 / 130502743),
which was also detected by the Swift/BAT (Troja et al. 2013, GCN 14527
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 ).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 20 degrees from Swift location.

The GBM light curve consists of a single pulse with a FRED-like shape
with a duration (T90) of about 3 s (50-300 keV).
The time-averaged spectrum from T0-0.384 s to T0+2.880 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.0 +/- 0.3 and
the cutoff energy, parameterized as Epeak, is 83 +/- 17 keV.

The event fluence (10-1000 keV) in this time interval is
(5.0 +/- 0.6)E-07 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0-0.064 s in the 8-1000 keV band
is 7 +/- 1 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

M.C. Stroh (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C.
Pagani (U. Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti
(INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), J.A. Kennea
(PSU) and E. Troja report on behalf of the Swift-XRT team:

We have analysed 2.3 ks of XRT data for GRB 130502A (Troja  et al. GCN
Circ. 14527
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 ),  from 76 s to 16.0 ks after the  BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.68 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+/-0.3). The
best-fitting absorption column is  1.6 (+0.8, -0.7) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 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 3.4 x 10^-11 (5.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.6 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 3.2 sigma
Photon index:	     2.2 (+/-0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00554996.

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

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

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

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

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

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 Kislovodsk was pointed to the  GRB130502A 55 sec  after notice 
time and 266 sec after GRB time at 2013-05-02 17:54:56.337 UT in two 
polarizations. On our first (50s exposure) set we haven`t found optical transient  within SWIFT 
error-box (E. Troja et. al. GCN 14527
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 ).
The 5-sigma upper limit has been about 18.5 mag
The message may be cited.

S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), A. Y. Lien (NASA/GSFC/ORAU),
T. Sakamoto (AGU), C. B. Markwardt (GSFC), W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU),
E. Troja (NASA/GSFC/UMCP), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130502A (trigger #554996)
(Troja, et al., GCN Circ. 14527
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 ).  The BAT ground-calculated position is
RA, Dec = 138.579, -0.134 deg, which is
   RA(J2000)  =  09h 14m 19.1s
   Dec(J2000) = -00d 08' 04.2"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 47%.

The mask-weighted light curve consists a single FRED pulse starting at
~T-0.3 sec, peaking at ~T+0.1 sec, and returning to baseline at ~T+4 sec.
T90 (15-350 keV) is 3.0 +- 0.3 sec (estimated error including systematics).

The time-averaged spectrum from T-0.19 to T+3.20 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.78 +- 0.16.  The fluence in the 15-150 keV band is 3.8 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.21 sec in the 15-150 keV band
is 2.9 +- 0.3 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/554996/BA/

V. Rumyantsev (CrAO), K.Antoniuk (CrAO), A. Pozanenko (IKI) report on 
behalf of larger GRB follow-up collaboration:

We observed the field of the Swift GRB 130502A (Troja et al., GCN 14527
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 ) 
with AZT-11 telescope of CrAO observatory on May 02 starting on (UT) 
18:20:46, i.e. ~30 min after burst trigger. We took several images in 
R-filter of 180 s exposure.  Within enchanced XRT position (Beardmore et 
al., GCN  14536
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 ) we do  not detect any source. Preliminary photometry of 
a combined image is following

T_start (UT)           T0+     Filter  Exp. OT  UpperLimit (3 sigma)
                        mid,days        s

2013-05-02T18:20:46.18 0.0419  R      3600  n/d 20.8

The photometry is based on USNO-B1.0  star 0898-0181247
09 14 15.80 -00 08 13.7 assuming R=18.02.