GRB 140919A

M.E. Gropp (PSU), S. B. Cenko (GSFC), C. Gronwall (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), V. Mangano (PSU),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
J. L. Racusin (NASA/GSFC) and B. Sbarufatti (INAF-OAB/PSU) report on
behalf of the Swift Team:

At 15:15:15 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140919A (trigger=613160).
The BAT on-board calculated location is
RA, Dec 221.556, -32.154 which is
    RA(J2000) = 14h 46m 13s
    Dec(J2000) = -32d 09' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger.

Due to an observing constraint, Swift will not slew until T0+48.2
minutes. There will be no XRT or UVOT data until this time.

Burst Advocate for this burst is M.E. Gropp (mgropp742 AT gmail.com).
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. Perri (ASDC), G. Tagliaferri (INAF-OAB), P.A. Evans (U. Leicester),
J.P. Osborne (U. Leicester), D.N. Burrows (PSU) and J.A. Kennea (PSU)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 140919A at 16:07:15.9 UT,
3120.4 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 221.53822,
-32.17586 which is equivalent to:
   RA(J2000)  = 14h 46m 09.17s
   Dec(J2000) = -32d 10' 33.1"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 95 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 7.65
x 10^20 cm^-2 (Willingale et al. 2013).

S. R. Oates (IAA-CSIC, MSSL-UCL) and M.E. Gropp (PSU) report 
on behalf of the Swift/UVOT team:

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 3124 seconds after the BAT trigger. No credible afterglow candidate
has been found in the initial data products. We note that within the XRT error 
circle (Perri et al., GCN Circ. 16832
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 ) there is a point source which is also 
observed in the DSS. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. 
The typical 3-sigma upper limit has been about 19.6mag. 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 18mag. 

No correction has been made for the expected extinction corresponding to
E(B-V) of 0.09.

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

Using 1892 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 140919A, 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 = 221.53734, -32.17629 which is equivalent
to:

RA (J2000): 14h 46m 8.96s
Dec (J2000): -32d 10' 34.7"

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.

V. Pelassa (UAH) and D. Yu (MPE) report on behalf of the Fermi GBM Team:

"At 15:15:13.54 UT on 19 September 2014, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 140919A (trigger 432832516 / 140919636),
which was also detected by the Swift/BAT (Gropp et al. 2014, GCN 16831
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 ).
The GBM on-ground location is consistent with the Swift position.
The angle of the Swift position from the Fermi LAT boresight is 34.6 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 109 s (50-300 keV).
The time-averaged spectrum from T0-5.12 s to T0+123.91 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.80 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 103 +/- 18 keV
(Castor statistics 1085.8 for 610 d.o.f.).

The event fluence (10-1000 keV) in this time interval is
(1.20 +/- 0.06)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+5.248 s in the 10-1000 keV band
is 3.6 +/- 0.2 ph/s/cm^2.

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

S. Schmidl (TLS Tautenburg), J. Bolmer and J. Greiner (both MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 140919A (Swift trigger 613160; Gropp et al.,
GCN #16831
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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 telescope at ESO La Silla
Observatory (Chile).

Observations started at 23:29 UT on 2014-09-19, 8.2 hrs after the GRB
trigger. They were performed at an average seeing of 1.7" and at an
average airmass of 2.1.

We detect a source inside the enhanced 1.5" Swift-XRT error cicle, at

RA  (J2000.0) =  14:46:08.96
DEC (J2000.0) = -32:10:34.6

with an uncertainty of 0.5" in each coordinate.

Based on total exposures of 7.7 minutes in g'r'i'z'and 24.0 minutes in
JHK, at a midtime of 9.2 hrs after the burst, we measure the following
preliminary magnitudes and upper limits (AB magnitude system):

g' = 19.8 +/- 0.1,
r' = 19.5 +/- 0.1,
i' = 19.4 +/- 0.1,
z' = 19.3 +/- 0.1,
J  = 18.9 +/- 0.1,
H  = 19.0 +/- 0.2, and
K  > 18.9.

At present we cannot decide if the source is fading.

Given magnitudes are calibrated against GROND zeropoints as well as
2MASS field stars and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V) = 0.09 mag
in the direction of the burst (Schlegel et al. 1998).

S. R. Oates (IAA-CSIC/UCL-MSSL) and M.E. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140919A
3125 s after the BAT trigger (Gropp et al., GCN Circ. 16831
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 ).
A fading source consistent with the optical and enhanced XRT position
(Schmidl et al. GCN Circ. 16836
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 ; Beardmore et al., GCN Circ 16834
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 )
is detected in the initial UVOT exposures. Initial identification 
was complicated by the presence of a point source in the 
DSS close to the optical position. Photometry is therefore also 
complicated by the presence of this point source. 

Preliminary detections 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)         3125         3275          147         16.62 +/- 0.05
white            45180        45480          295         19.40 +/- 0.11
v                 4848         5047          197         17.33 +/- 0.10
b                 8834         9134          295         18.34 +/- 0.09
u                 5462         5613          148         16.86 +/- 0.07
w1                5258         5458          197         16.98 +/- 0.09
m2                5052         5252          197         17.12 +/- 0.11

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).

M.E. Gropp (PSU) reports on behalf of the Swift-XRT team:

We have analysed 12 ks of XRT data for GRB 140919A (Gropp  et al. GCN
Circ. 16831
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 ),  from 3.1 ks to 57.4 ks after the  BAT trigger. The data
comprise 99 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Beardmore et al. (GCN Circ. 16834
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 ).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.00 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+/-0.10). The
best-fitting absorption column is  1.54 (+0.30, -0.29) 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 3.3 x 10^-11 (4.4 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.54 (+0.30, -0.29) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: 4.5 sigma
Photon index:	     2.05 (+/-0.10)

If the light curve continues to decay with a power-law decay index of
1.00, the count rate at T+24 hours will be 0.061 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-12 (2.7 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/00613160.

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

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

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140919A (trigger #613160)
(Gropp, et al., GCN Circ. 16831
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 ).  The BAT ground-calculated position is
RA, Dec = 221.540, -32.153 deg which is
  RA(J2000)  =  14h 46m 09.5s
  Dec(J2000) = -32d 09' 11.5"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 14%.

The mask-weighted light curve shows a multi-peaked structure starts at ~ T-1 s and
ends at ~T+175 s. The structure includes roughly three peaks at ~T+3 s, ~T+40 s,
and ~T+90 s, respectively. T90 (15-350 keV) is 151.3 +- 25.6 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.7 to T+174.6 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.74 +- 0.12.  The fluence in the 15-150 keV band is 5.9 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+38.97 sec in the 15-150 keV band
is 2.0 +- 0.5 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/613160/BA/