GRB 130605A

S. T. Holland (STScI), S. D. Barthelmy (GSFC),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), M. H. Siegel (PSU) and
M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team:

At 23:41:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130605A (trigger=557508).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 134.524, -33.489 which is 
   RA(J2000) = 08h 58m 06s
   Dec(J2000) = -33d 29' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
with a duration of about 8 sec.  The peak count rate was ~2000 counts/sec 
(15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 23:43:14.6 UT, 92.6 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the
XRT counterpart. No prompt event mode data were available as Swift entered
the SAA shortly after the burst was detected. 

UVOT took a finding chart exposure of 107 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 25% of
the BAT 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
BAT 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
0.36. 

Burst Advocate for this burst is S. T. Holland (sholland AT stsci.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.)

Nicuesa Guelbenzu, A. (TLS Tautenburg), J. Greiner, Varela, K. (MPE 
Garching), S. Klose, D. A. Kann (TLS Tautenburg) report on behalf of the 
GROND team:

We observed the field of GRB 130605A (Swift trigger 557508; Holland et 
al., GCN 14773
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 
2008, PASP 120, 405) mounted at the 2.2m MPG/ESO telescope at La Silla 
Observatory (Chile).

Observations started at 23:44:36 UT on June 6, about 3 min after the GRB 
trigger. Inside the BAT error circle (Holland et al., GCN 14773
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 ) we find a 
source at coordinates RA, DEC (J2000) = 08:58:08.6, -33:27:40.3 which has 
no counterpart on the DSS2 red. We measure the following preliminary AB 
magnitude (mean time 23:47:39)

r' = 15.8 +/- 0.1,

calibrated against GROND zeropoints and 2MASS stars. We suggest that this 
is the GRB afterglow.

Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP),
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 130605A detected by SWIFT
(trigger 557508) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 32.7s after the GRB trigger
(12.8s after the notice). The elevation of the field decreased from
51 degrees above horizon and weather conditions
were excellents.

We detect a new fading source in the error box given by SWIFT
at the following position (+/- 3 arcsec):

RA(J2000.0)  = 08h 58m 08.53s
DEC(J2000.0) = +33d 27' 40.1"

OT was R = 15.1 at  121s after GRB.
OT was R = 18.4 at 1705s after GRB.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
The afterglow is seen but the trail is overlaped
by another star and will be analyzed in details
later.

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=257.1493 lat= +7.9340
and the galactic extinction in R band is about 0.9 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

A. Trotter, A. Lacluyze, D. Reichart, J. Haislip, T. Berger, M. Carroll, 
H. T. Cromartie, R. Egger, A. Foster, C. Foster, N. Frank, K. Ivarsen, 
D. James, M. Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor 
and J. A. Crain report

Skynet observed the Swift/BAT localization of GRB 130605A (Holland et 
al., GCN 14773
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 , Swift trigger #557508) with three 16" telescopes of the 
PROMPT array at CTIO, Chile.  Starting at 2013-06-05, 23:43:23 UT 
(t=101s post-trigger)

We detect a fading afterglow in B, V and I bands at the position 
reported by Guelbenzu et al. (GCN 14774
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 ).  Preliminary magnitudes at 
t=10.4m are
B = 17.9
V = 17.1
I = 15.7
Magnitudes are in the Vega system, calibrated to 3 APASS stars in the 
field, and are not corrected for Milky Way extinction.

Skynet observations are ongoing.

Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP),
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:

We analyzed TAROT La Silla images taken during the first hours
after the GRB 130605A (Holland et al. GCNC 14773).
We have a photometric follow-up of the afterglow
detected by Nicuesa Guelbenzu et al. (GCNC 14774).

All TAROT magnitudes are computed using the reference star
NOMAD-1 0565-0204137 (RA = 134.5240528 Dec. = -33.4675072 R=12.50).

The first TAROT image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
After substraction of an overlaped star we can mesure the
continuous photometry between 32.7 and 92.7s:

 From 32.7s to 58.5s the magnitude rises steeply until R = 14.85
 From 58.5s to 92.7s the magnitude stays at about the level R = 14.9

Then the decay is recorded using the later images:

  Tstart  Tstop  Rmag  1sig
  (sec)   (sec)
   106.3  136.3  15.20 0.02
   146.8  176.8  15.43 0.02
   187.4  217.4  15.56 0.02
   227.7  257.7  15.70 0.03
   268.5  298.5  16.10 0.02
   308.8  398.8  16.17 0.02
   409.4  499.4  16.45 0.04
   509.9  599.9  16.71 0.08
   610.5  700.5  16.98 0.04
   711.3 1161.3  17.88 0.07
  1113.3 1203.3  18.36 0.29
  1414.9 1684.9 >18.57
  1515.5 4845.5 >19.41

The light curve can be fitted in three parts implying
two breaks at 284s and 656s:

 From  76s to 284s alpha=0.65
 From 284s to 656s alpha=1.3
Beyond 656s       alpha=2.2

This message can be cited.

A. Trotter, A. Lacluyze, D. Reichart, J. Haislip, T. Berger, M. Carroll, 
H. T. Cromartie, R. Egger, A. Foster, C. Foster, N. Frank, K. Ivarsen, 
D. James, M. Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor 
and J. A. Crain report

Skynet observed the Swift/BAT localization of GRB 130605A (Holland et 
al., GCN 14773
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 , Swift trigger #557508) with three 16" telescopes of the 
PROMPT array at CTIO, Chile,  starting at 2013-06-05, 23:43:23 UT 
(t=101s post-trigger), and continuing until t=3h. Exposure lengths range 
from 10s at early times to 160s at later times.  Multiple 160s exposures 
were stacked at later times to increase sensitivity.

We detect a fading afterglow in B, V and I bands at the position 
reported by Nicuesa Guelbenzu et al. (GCN 14774
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 ), at:
RA   08:50:08.6
Dec -33:27:40.3

 From t=1.7m to t=9m, the afterglow fades with an approximate temporal 
index alpha~-0.7, after which it steepens to alpha~-1.4.  A preliminary 
light curve is at:
http://www.skynet.unc.edu/grb/grb130605a.png

Magnitudes are in the Vega system, calibrated to 3 APASS stars in the 
field, and are not corrected for the expected Milky Way extinction of 
E(B-V)=1.12 (Schlegel et al. 1998), which, assuming R_V=3.1, corresponds to:
band      B       V       I
A_lambda  1.57    1.17    0.71

No further Skynet observations are scheduled.

B. Porterfield (PSU) and S. T. Holland (STScI)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 
130605A 96 s after the BAT trigger (Holland et al., GCN Circ. 14773
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 ).
A source consistent with the optical position(Guelbenzu et al. GCN
Circ. 14774
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 ) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) = 08:58:08.61 = 134.53587 (deg.)
    Dec (J2000) = -33:27:40.2 = -33.46118 (deg.)
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).

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

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

white fc       95          202         105     16.40+-0.07
wh           5498         5698         196     21.04+-0.29
v            4474         6109         393     19.90+-0.36
b            5294        30053        1355    >21.70
u            5089        35820        3306    >21.45
w1           4884        35150        3778    >21.57
m2           4679        34243        2860    >21.02
w2           5705        39258         421    >20.27

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.36 in the direction
of the burst (Schlegel et al. 1998).

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), S. T. Holland (STScI), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
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-61 to T+242 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130605A (trigger #557508)
(Holland, et al., GCN Circ. 14773
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 ).  The BAT ground-calculated position is
RA, Dec = 134.536, -33.477 deg, which is 
   RA(J2000)  =  08h 58m 08.7s 
   Dec(J2000) = -33d 28' 36.5" 
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 5%.
 
The mask-weighted light curve shows a single peak starting at ~T-5 sec,
peaking at ~T+2 sec, and ending at ~T+45 sec.  T90 (15-350 keV)
is 12.6 +- 3.1 sec (estimated error including systematics).
 
The time-averaged spectrum from T-6.48 to T+9.18 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.58 +- 0.17.  The fluence in the 15-150 keV band is 2.6 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.14 sec in the 15-150 keV band
is 4.1 +- 0.9 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/557508/BA/

A. Melandri (INAF/OAB) and S. T. Holland (STScI) report on behalf of
the Swift-XRT team:

We have analysed 15 ks of XRT data for GRB 130605A (Holland  et al. GCN
Circ. 14773
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 ),  from 78 s to 58.5 ks after the  BAT trigger. The data
comprise 385 s in Windowed Timing (WT) mode (the first 8 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. Using 6133 s of PC mode data and 5 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 134.53571, -33.46152
which is equivalent to:

RA (J2000): 08h 58m 08.57s
Dec(J2000): -33d 27' 41.5"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.23 (+/-0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.3 (+0.5, -0.3). The
best-fitting absorption column is  2.35 (+1.96, -0.16) x 10^21 cm^-2,
consistent with the Galactic value of 2.2 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 2.7 x 10^-11 (5.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     2.35 (+1.96, -0.16) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.3 (+0.5, -0.3)

If the light curve continues to decay with a power-law decay index of
1.23, the count rate at T+24 hours will be 9.4 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x
10^-14 (4.7 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00557508.

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

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:

The long-duration GRB 130605A
(Swift-BAT trigger 557508: Holland, et al., GCN 14773
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 ;
Barthelmy, et al., GCN 14787
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 )
triggered Konus-Wind at T0=85303.441s UT (23:41:43.441)

The burst light curve shows a single pulse from ~T0-1 s to ~T0+5 s.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130606_T85303/

As observed by Konus-Wind, the burst
had a fluence of (3.4 � 0.4)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.320 s,
of (2.5 � 0.3)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 5 MeV range by a simple power-law
model with the photon index 2.19 � 0.07, chi2 = 80/69 dof.

All the quoted results are preliminary.

D. Frederiks, on behalf of the Konus-Wind team:

The correct URL for the Konus-Wind light curve of GRB 130605A is:
http://www.ioffe.ru/LEA/GRBs/GRB130605_T85303/

We are sorry for the inconvenience.