GRB 140730A

C. B. Markwardt (NASA/GSFC), M. G. Bernardini (INAF-OAB),
P. D'Avanzo (INAF-OAB), N. Gehrels (NASA/GSFC),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 19:43:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140730A (trigger=607742).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 56.431, -66.539 which is 
   RA(J2000) = 03h 45m 43s
   Dec(J2000) = -66d 32' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 5 sec (FWHM ~2-3 sec)  The peak 
count rate was ~1800 counts/sec (15-350 keV), at ~1 sec after the 
trigger. 

The XRT began observing the field at 19:44:55.1 UT, 63.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 56.39573, -66.54597 which is equivalent
to:
   RA(J2000)  = 03h 45m 34.98s
   Dec(J2000) = -66d 32' 45.5"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 56 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 7.59
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 68 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 0.09. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt 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.)

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 140730A, we find an
enhanced XRT position of the afterglow: RA, Dec: 56.3982, -66.5456
which is equivalent to:
   RA (J2000)  = 03 45 35.56
   Dec (J2000) = -66 32 44.0
with an uncertainty of 2.3 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/607742.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

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

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

Using 2499 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 140730A, 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 = 56.39911, -66.54516 which is equivalent
to:

RA (J2000): 03h 45m 35.79s
Dec (J2000): -66d 32' 42.6"

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.

M. H. Siegel (PSU) and C. B. Markwardt (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140730A
68 s after the BAT trigger (Markwardt et al., GCN Circ. 16642
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 ).
No optical afterglow consistent with the XRT position
(Evans GCN Circ. 16643
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 )
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            68          218          147         >21.2
u_FC               280          530          246         >19.6
white               68         6182          396         >21.3
v                  784         6593          413         >19.5
b                  709         5978          216         >20.3
u                  280         5772          462         >20.0
w1                 660         5568          236         >21.1
m2                5162         6798          393         >20.4
w2                4753         6388          393         >20.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).

A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz
(U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de
Pasquale (INAF-IASFPA), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A.
Kennea (PSU) and C.B. Markwardt report on behalf of the Swift-XRT team:

We have analysed 6.1 ks of XRT data for GRB 140730A (Markwardt	et al.
GCN Circ. 16642
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 ),  from 50 s to 39.5 ks after the  BAT trigger. The
data comprise 17 s in Windowed Timing (WT) mode (the first 7 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by Goad
et al. (GCN Circ. 16643
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 ).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.4 (+0.4, -0.3), followed by a break at T+234 s to an
alpha of 0.57 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.92 (+0.25, -0.23). The
best-fitting absorption column is  3.0 (+1.1, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 7.6 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.9 x 10^-11 (5.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.0 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: 3.8 sigma
Photon index:	     1.92 (+0.25, -0.23)

If the light curve continues to decay with a power-law decay index of
0.57, the count rate at T+24 hours will be 10.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x
10^-13 (5.5 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00607742.

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

S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (LJMU),
A. Gomboc (U. Ljubljana) on behalf of a large collaboration report:

One of the Las Cumbres Observatory 1-m telescopes in Sutherland
(South Africa) began observing Swift GRB 140730A (Markwardt et al.
GCN Circ 16642
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 ) on July 31 at 01:16:34 UT, i.e.
~5.5 hours after the BAT trigger, with the r' and i' filters.

Within the enhanced XRT error circle (Goad et al. GCN Circ. 16644
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 )
we found nothing down to the following limit:

Mid time from  Total Exp   Filter    Magnitude
trigger (hr)   (s)
-------------------------------------------------
5.64           120x5       r'        > 20.0
5.83           120x5       i'        > 19.8
-------------------------------------------------

Magnitudes are calibrated against nearby USNO-B1 stars.

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC),
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-240 to T+902 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140730A (trigger #607742)
(Markwardt, et al., GCN Circ. 16642
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 ).  The BAT ground-calculated position is
RA, Dec = 56.350, -66.580 deg which is
  RA(J2000)  =  03h 45m 24.0s
  Dec(J2000) = -66d 34' 48.7"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows several overlapping pulses. The first major
pulse starts at ~T-14s, peaks at  ~T-13 s, and ends at ~T-4 s. The second major pulse
starts at ~T+0 s, peaks at ~T+1s, and ends at ~T+5 s. The whole burst structure ends
at ~T+41 s. T90 (15-350 keV) is 41.3 +- 3.7 sec (estimated error including systematics).

The time-averaged spectrum from T-13.5 to T+29.6 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.50 +- 0.32.  The fluence in the 15-150 keV band is 2.8 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.17 sec in the 15-150 keV band
is 0.5 +- 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/607742/BA/

D. A. Kann (TLS Tautenburg), C. Delvaux and Jochen Greiner (both MPE
Garching) report on behalf of the GROND team:

We observed the field of GRB 140730A (Swift trigger 607742; Markwardt et
al., GCN #16642
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 08:36 UT on 2014-08-02, 2.52 days after the GRB
trigger. They were performed at an average seeing of 1".2 and at an
average airmass of 1.4.

Based on images with exposure times of 2250 s in g'r'i'z' and 1200 s in
JHK, we do not detect a source within the Swift-XRT error circle reported
by Goad et al. (GCN #16644
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 ) down to to the following 3-sigma AB
magnitudes:

g' > 25.3 mag,
r' > 25.4 mag,
i' > 24.7 mag,
z' > 24.4 mag,
J > 21.0 mag,
H > 20.3 mag, and
K > 18.0 mag.

The given limits are derived based on calibrating the images against the
GROND zeropoints and 2MASS field stars and are not corrected for the
Galactic foreground extinction corresponding to a reddening of E_(B-V)=
0.09 in the direction of the burst (Schlegel et al. 1998).