GRB 140509A

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), V. Mangano (PSU), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 02:22:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140509A (trigger=598497).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 46.608, -62.654 which is 
   RA(J2000)  =  03h 06m 26s
   Dec(J2000) = -62d 39' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 30 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 02:24:06.1 UT, 112.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 46.5952,
-62.6396 which is equivalent to:
   RA(J2000)  = 03h 06m 22.84s
   Dec(J2000) = -62d 38' 22.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 55 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 (2.23 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.6
(+2.56/-2.25) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 5.99e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
279 seconds after the BAT trigger. There is a candidate afterglow in the list
of sources generated on-board at
 RA(J2000)  =	03:06:22.67 =  46.59444
 DEC(J2000) = -62:38:21.7  = -62.63937
with a 90%-confidence error radius of about 1.10 arc sec. This position is 1.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.24. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.02. 

Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 
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.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1253 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 140509A, 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 = 46.59538, -62.63941 which is equivalent
to:

RA (J2000): 03h 06m 22.89s
Dec (J2000): -62d 38' 21.9"

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.

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), J.A. Kennea (PSU), V. Mangano (PSU), M.C. Stroh
(PSU) and K.L. Page report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 140509A (Page  et al. GCN
Circ. 16230
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 ),  from 102 s to 13.0 ks after the	BAT trigger. The data
comprise 137 s in Windowed Timing (WT) mode (the first 8 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 Beardmore
et al. (GCN Circ. 16233
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 ).

The light curve can be modelled with an initial power-law decay with an
index of alpha=1.43 (+0.18, -0.08), followed by a break at T+1030 s to
an alpha of 0.88 (+0.12, -0.10).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.66 (+0.17, -0.16). The
best-fitting absorption column is  4.9 (+4.5, -2.6) x 10^20 cm^-2,
consistent with the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et
al. 2013). The PC mode spectrum has a photon index of 1.91 (+/-0.14)
and a best-fitting absorption column of 7.4 (+3.6, -3.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.4 x 10^-11 (4.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     7.4 (+3.6, -3.3) x 10^20 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index:	     1.91 (+/-0.14)

If the light curve continues to decay with a power-law decay index of
0.88, the count rate at T+24 hours will be 8.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x
10^-13 (3.3 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/00598497.

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

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), 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+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140509A (trigger #598497) (Page, et al.,
GCN Circ. 16230
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 ).  The BAT ground-calculated position is
RA, Dec = 46.564, -62.662 deg which is
    RA(J2000)  =  03h 06m 15.3s
    Dec(J2000) = -62d 39' 43"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 19%.
  
The mask-weighted light curve shows a single FRED peak.  T90 (15-350 keV) is
23.20 +- 5.17 sec (estimated error including systematics).
  
The time-averaged spectrum from T-3.8 to T+23.1 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.59 +- 0.20.  The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+1.78 sec in the 15-150 keV band
is 1.6 +- 0.4 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/598497/BA/

F. E. Marshall (NASA/GSFC) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140509A
121 s after the BAT trigger (Page et al., GCN Circ. 16230
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 ).
A source consistent with the XRT position
(Beardmore et al. GCN Circ. 16233
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 )
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  03:06:22.69 =  46.59456 (deg.)
    Dec (J2000) = -62:38:21.7  = -62.63935 (deg.)
with an estimated uncertainty of 0.42 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              121          271          147         17.00 +/- 0.03
v                  610          630           20         16.50 +/- 0.13
b                  536          556           20         17.04 +/- 0.10
u                  280          530          246         16.35 +/- 0.03
w1                 659         7011          490        >20.6
m2                 634         6806          490        >21.1
w2                 585         6396          432        >20.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).

The lack of detections in the UV filters suggests a redshift of about 2.4.

P. Schady (MPE Garching), A. Nicuesa Guelbenzu (TLS Tautenburg)  and J. Greiner (MPE Garching) 
report on behalf of the GROND team:

We observed the field of GRB 140509A (Swift trigger 598497; Page et al., GCN #16230
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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 La Silla Observatory
(Chile).

Observations started at 10:07 UT on 09 May 2014, about 8 hours after the GRB trigger. They were performed at high airmass and a mean seeing of 1.4".

Using the first ~8 minutes of data with a midtime of 10.18UT after the trigger, we detect a source consistent with the UVOT position (Marshall et al., GCN #16241
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 ) with the following AB magnitudes:

g� = 21.6 +/- 0.2
r' = 21.1 +/- 0.1 
i' = 20.9 +/- 0.1
z' = 20.7 +/- 0.1
J = 20.4 +/- 0.4
H = 20.1 +/- 0.4
K > 20.0

In a later epoch of observations taken on September 24th the source is no longer detected in any of the optical or NIR filters down to the following AB 3sigma limits:

g� > 25.8
r� > 25.3
i� > 24.7
z� > 24.3
J > 22.1
H > 21.6
K > 20.7

thus confirming that the source detections in our initial observations corresponded to the GRB optical afterglow and not to a potential host. 

All given magnitudes are calibrated against GROND zero points in the optical, and against 2MASS field stars in the NIR, and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.02 mag in the direction of the burst (Schlegel et al. 1998).