GRB 150309A

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL)
report on behalf of the Swift Team:

At 23:03:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150309A (trigger=634200).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 276.987, +86.430, which is 
   RA(J2000)  =  18h 27m 57s
   Dec(J2000) = +86d 25' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a peak around T+30 sec
with a duration of about 60 sec.  The peak count rate
was ~200 counts/sec (15-350 keV), at ~45 sec after the trigger. 

The XRT began observing the field at 23:05:18.2 UT, 131.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 277.08842, 86.42988 which
is equivalent to:
   RA(J2000)  = 18h 28m 21.22s
   Dec(J2000) = +86d 25' 47.6"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 22 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 in excess of the Galactic value (9.05 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.4
(+3.89/-3.10) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 2.73e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 140 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
0.14. 

Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.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.)

R. Cunniffe, M. Jelinek, Y. Hu, S. Jeong, S. R. Oates (IAA-CSIC), B.-B. Zhang
(IAA-CSIC and UAH) and A. J. Castro-Tirado (IAA-CSIC and ISA-UMA), on behalf of a
larger collaboration, report:

Both the 60 cm BOOTES-2/TELMA and the 30 cm BOOTES-1 robotic telescopes in
South Spain automatically responded to the Swift trigger of GRB 150309A
(Cummings et al., GCN 17553
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 ). The first exposure started at 23:04:33 UT
(86s after the trigger) and a sequence of 20 images was obtained (3s each,
clear filter). A median combined image revealed no optical counterpart at
the enhanced XRT error circle down to 18 mag. Further observations are
ongoing.

[GCN OPS NOTE(10mar15): Per author's request, the affilliation of B-BZ was changed.]

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

Using 853 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 150309A, 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 = 277.10213, +86.42875 which is equivalent
to:

RA (J2000): 18h 28m 24.51s
Dec (J2000): +86d 25' 43.5"

with an uncertainty of 1.5 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. Melandri (INAF-OAB), D. Kopac (LJMU), R. J. Smith (LJMU), C. G. Mundell (U. Bath) and A. Gomboc (U. Ljubljana), on behalf of a large collaboration report:

The 2-m Liverpool Telescope robotically followed up Swift GRB 150309A (Cummings et al., GCN 17553
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 ) at 23:06:37 UT (~3.5 min after the burst trigger).

No optical counterpart is detected at the enhanced XRT error circle (Osborne et al., GCN 17555
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 ) down to r > 19.5 mag (~37 min after burst).

J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), K.L. Page (U.
Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA),
D.N. Burrows (PSU) and J.R. Cummings report on behalf of the Swift-XRT
team:

We have analysed 6.9 ks of XRT data for GRB 150309A (Cummings et al.
GCN Circ. 17553
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 ), from 122 s to 17.9 ks after the  BAT trigger. The
data comprise 273 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
Osborne et al. (GCN Circ. 17555
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 ).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.11 (+0.09, -0.07), followed by a break at T+477 s to
an alpha of 0.98 (+/-0.04).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.82 (+/-0.07). The
best-fitting absorption column is  2.03 (+0.28, -0.27) x 10^21 cm^-2,
in excess of the Galactic value of 9.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.91 (+0.12, -0.11)
and a best-fitting absorption column of 2.8 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.9 x 10^-11 (5.4 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.8 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 9.1 x 10^20 cm^-2
Excess significance: 6.6 sigma
Photon index:	     1.91 (+0.12, -0.11)

If the light curve continues to decay with a power-law decay index of
0.98, the count rate at T+24 hours will be 0.022 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.4 x
10^-13 (1.2 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/00634200.

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

E. Gorbovskoy, V. Lipunov, N.Tyurina, P.Balanutsa, A.Kuznetsov,
D.Kuvshinov, V.Kornilov, 
Lomonosov Moscow State University,
Sternberg Astronomical Institute

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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

V.Krushinsky,
Ural Federal University, Yekaterinburg, 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 ( Lipunov et al., Advances in Astronomy, vol. 
2010, pp. 1-7, MASTER Global Robotic Net, 2010) 
located in Kislovodsk was pointed to the  GRB150309A 21 sec after notice 
time and 96 sec after trigger time at 2015-03-09 23:04:45 UT in two 
polarizations. On our first (20s exposure)  set we not  found  optical 
transient within SWIFT error-box (Cummings et al GCN 17553
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 ) brighter then 
17.2

Before this, the MASTER serial pointed to  FERMI (trig. N 447634793) 
coordinates. Due to this pointings we have a two images from MASTER VWF 
very wide fild camera  obtained at 2015-03-09 23:00:34 i.e. 152 sec before 
SWIFT BAT and  44 sec after FERMI GBM trigger times. We not found new OT 
on this 5 sec exposure images with upper limit 12.0 at SWIFT position.

Table 1. GRB 150309A MASTER optical upper limits.

Tstart  Tst-T0 Tmid-T0 Expt Mlimit  Instrum.   Coadd.
23:00:34  -152    -149    5 12.0    MASTER VWF   no
23:04:45    98     108   20 17.2    MASTER II    no
23:04:45    98     559  780 19.3    MASTER II    10
23:20:20  1033    2363 2160 20.0    MASTER II    12

T0 - is a SWIFT trigger time.

The message may be cited.

S. R. Oates (IAA-CSIC/UCL-MSSL) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150309A
140 s after the BAT trigger (Cummings et al., GCN Circ. 17553
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 ).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 17555
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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           140          290          147         >20.3
u_FC               299          549          246         >19.4
white              140        12463          881         >21.1
v                  630         6293          432         >19.3
b                  555        12046         1121         >20.8
u                  299        17720         2241         >21.1
w1                 679        16806         1318         >20.8
m2                 654         6498          432         >20.1
w2                 605         6089          432         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).

B. Dintinjana, S. Maticic and H. Mikuz on behalf of PIKA observing 
program at Crni
Vrh Observatory.

We observed the field of GRB 150309A (Cummings et al., GCN 17553
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 ) from 
Crni Vrh Observatory with a 60 cm robotic telescope and clear filter. 
Twenty six consecutive exposures of 60 second duration were taken in 
moonlight conditions. First exposure started at 2015-03-09 23:05:34 UT, 
68 seconds after the SWIFT trigger.

No optical candidate was detected within the uncertainty radius on 
single exposures, having limiting magnitude 19.2, calibrated against the 
nerby USNO-B R2 magnitude stars. Also we found no optical candidate on 
26 sumed unfiltered images with total exposure of 1560 seconds and 
limiting magnitude 20.8 (calibrated against the nerby USNO-B R2 
magnitude stars).

O.J Roberts (UCD) and M. Stanbro (UAH) report on behalf
of the Fermi GBM Team:

"At 22:59:50.66 UT on the 9th of March 2015, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 150309A (trigger 447634793/150309958), the second
episode of which was also detected by Swift
(Cummings et al. 2015, GCN 17553
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 ). The GBM on-ground
location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 60 degrees.

The Swift trigger is observed in the GBM light curve at
T0+200 s as a very soft, weak event with a duration of
about 60 s. The immediate light curve at the GBM trigger
time consists of a bright, main peak of unresolved emission
episodes, with a duration (T90) of about 52 s (50-300 keV).
The time-averaged spectrum from T0+0.0 s to T0+52.6 s is
best fit by a Band function with Epeak= 165 +/- 4 keV,
alpha = -0.59 +/- 0.02 and beta = -2.59 +/- 0.10.

The event fluence (10-1000 keV) in this time interval is
(3.9 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+17.5 s in the 10-1000 keV band
is 15.2 +/- 0.3 ph/s/cm^2.

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

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
N. Gehrels (GSFC), 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), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+471 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150309A (trigger #634200) (Cummings, et
al., GCN Circ. 17553
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 ).  The BAT ground-calculated position is
RA, Dec = 277.004, 86.417 deg which is
   RA(J2000)  =  18h 28m 01.0s
   Dec(J2000) = +86d 25' 02.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows that the main peak of the burst, which
occurred during a Swift preplanned slew maneuver, started at about T-200 seconds.
The roughly symmetrical peak with multiple maxima lasted until about T-160
seconds.  A weaker overlapping peak followed at about T-150 seconds and declined
to background by about T-60 seconds.  BAT triggered on a smaller peak that lasted
from about T+0 seconds to about T+120 seconds.  T90 (15-350 keV) is
242 +- 6 sec (estimated error including systematics).  Because the source came
into the BAT field of view during the slew, it is possible that there was some
additional low-level emission before T-200 seconds.

The time-averaged spectrum from T-197.32 to T+119.08 sec is best fit by a power
law with an exponential cutoff.  This fit gives a photon index 1.05 +- 0.16,
and Epeak of 175.8 +- 76.0 keV (chi squared 37.47 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.7 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T-177.49 sec in the 15-150 keV band is
9.0 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.36 +- 0.04 (chi squared 49.55 for 57 d.o.f.).  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/634200/BA/

E. Vazaeva (IKI), V. Nevskiy (ISON), A. Volnova (IKI), I. Molotov 
(KIAM), A. Pozanenko (IKI),report on  behalf of larger collaboration:

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553
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 ) with Santel-400AN   telescope of ISON-Kislovodsk observatory 
starting on Mar. 09 (UT) 23:11:26, i.e. ~8.5 min after the burst 
trigger. In the enhanced XRT position (Osborne et al., GCN 17555
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 ) we do 
not detect any object. An upper limit is following

Date       UT start   t-T0    Filter   Exp.     UL(3 sigma)
                      (mid, days)        (s)

2014-09-03 23:11:26  0.02590  None     49*60    20.0

The photometry is based on USNO-B1.0 star

USNO-B1.0_id  R2

1764-0030460  15.42

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

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553
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 ) with AZT-11 telescope of CrAO observatory starting on Mar. 09 
(UT) 23:39:47. We took several images in R-filter of 180 s exposure. In 
the enhanced XRT position (Osborne et al., GCN 17555
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 ) we do not detect 
any object. An upper limit is following

Date       UT start,  t-t0     Filter   Exp.      UL (3 sigma)
                       (mid, days)        (s)

2015-03-09 23:39:47   0.0468   R        20*180    20.9

The photometry is based on nearby USNO-B1.0  stars.

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

The long-duration GRB 150309A (Swift-BAT trigger #634200:
Cummings et al., GCN 17553
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 ; Baumgartner et al., GCN 17562
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 )
triggered Konus-Wind at T0=82792.708 s UT (22:59:52.708).

The KW light curve shows a broad emission pulse which
starts at ~T0-7 s and decays to ~T0+55 s.
The pulse is followed by a weak soft emission detectable
up to ~T0+250 s.
The emission is visible up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150309_T82792/

As observed by Konus-Wind, the burst had a fluence
of 4.1(-0.4,+0.5)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+16.832 s, of 4.0(-0.4,+0.4)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+53.248 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.79 (-0.09,+0.11),
the high energy photon index beta = -2.79 (-0.48,+0.29),
the peak energy Ep = 182 (-17,+14) keV,
chi2 = 101/97 dof.

The spectrum near the peak count rate
(measured from T0+8.448 to T0+20.480 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.64 (-0.09,+0.11),
the high energy photon index beta = -2.73 (-0.34,+0.22),
the peak energy Ep = 197 (-17,+16) keV,
chi2 = 110/97 dof.

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO),   A. 
Volnova (IKI), Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the Swift GRB 150309A (Cummings et al., GCN 
17553
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 )  with AS-32 (0.7m) telescope of Abastumani Observatory starting 
on Mar. 10 (UT) 01:40:54.  Within the enhanced XRT position (Osborne et 
al., GCN 17555
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 ) we do not detect any object. An upper limit is following

Date       UT start   t-T0    Filter   Exp.     UL(3 sigma)
                      (mid, days)        (s)

2015-03-10 01:40:54  0.12699  None     19*120   21.2

The photometry is based on USNO-B1.0 star

USNO-B1.0_id  R2

1764-0030460  15.42