GRB 140809A

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


K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

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

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

V.Krushinsky, I.Zalozhnih,  A. Popov
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 (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was starting survey on the FERMI  GRB140809A 
error-box (ra=11 15 14 dec=+71 00 36 r=6.040000)  52916 sec after trigger 
time at 2014-08-09 17:53:06 UT.

  During the observations of the error box of possible GRB 140809A (Fermi 
trigger 429246673) MASTER-Tunka auto-detection system discovered OT source 
at (RA, Dec) = 11h 46m 55.24s +66d 09m 59.3s on 2014-08-09.63454 UT ( 
Shumkov et al., Atel #6379). The 
OT unfiltered magnitude is 17.0m (limit 19.1m). The OT is seen in 6 
images. There is no minor planet at this place. We have reference image 
without OT on 2014-04-21.58762 UT with unfiltered magnitude limit 20.0m.

The new object is located 1.5" east and 17" north of the center of galaxy 
PGC 36760 = SDSS J114654.97+660942.3 (g=15.34 r=14.73 i=14.42) with 
z=0.0413. Discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/114655.24660959.3.png

It is   just a chance coincidence possible. Spectral and photometric 
confirmation is requested. Observations in X-rays and other wave bands are 
also strongly encouraged.

The OT search is continuated.

This message can be cited.

G. Masi, the Virtual Telescope Project - Italy, reports:

I observed the field of GRB 140809A (FERMI trigger
429246673) with with the 17" 
robotic unit part of the Virtual Telescope (Ceccano, Italy:
http://www.virtualtelescope.eu) at 9 Aug. 2014, 20:15:24 UT.

An optical source is visible where described by Shumkov et
al. (GCN 16674
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 )  in 180-seconds integration images,
unfiltered. The position of the source is RA: 11 46 54.89
Decl.:+66 10 00.5 (J2000.0, mean residuals of 0.2") and the
magnitude was estimated to be 17.4 assuming R mags for the
reference stars from UCAC-4.

The message may be cited.

NPM Kuin (UCL/MSSL), K.L.Page (U. Leicester) and F. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of Fermi Trigger
429246673 (GRB 140809A) as follow-up on the GRB candidate reported
detected by MASTER (Shumkov et al. (ATEL 6379) and confirmed by Masi
(GCN Circ. No 16675).  Swift observations started on  2014-08-10T00:55,
77.2 ks after the Fermi trigger.

We have analysed 2.0 ks of XRT data collected between 77.2-79.2 ks after
the trigger. No X-ray source was found, to an upper  limit of 4.0x10^-3
count s^-1 (3-sigma; 0.3-10 keV).

The UVOT observed the candidate field taking three v-band, one uvm2 and
one uvw2 exposure. The new source is found at the edge of a galaxy
(CG +11-15-003 at z=0.041372) and is only seen in the v-band, while the
uv bands appear dominated by galaxy emission. The source position is
consistent with that reported by Masi (GCN CIRC. No 16675).

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

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

 v            78122        79027          885         17.27 +/- 0.05
 m2           79032        79208          174         18.78 +/- 0.26
 w2           77214        78114          886         18.74 +/- 0.11

Times given relative to 2014-08-09T03:11:10.2.
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).

The source brightness remains close to the unfiltered magnitude reported by
MASTER, and has no X-ray counterpart.  Is therefore unlikely to be a GRB.

Oliver Roberts (UCD) and V��ronique Pelassa (UAH)
reports on behalf of the Fermi GBM Team:

"At 03:11:10.20 UT on the 9th of August 2014, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 140809A
(trigger 429246673 / 140809133), for which a possible optical
transient was also detected by the MASTER II robotic telescope
(Lipunov et al. 2014, GCN 16674
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 ). The GBM on-ground location is
consistent with the OT position. The angle from the Fermi LAT
boresight is 40 degrees.

The GBM light curve consists of one bright pulse, followed by
a sequence of shorter, dimmer pulses with a duration (T90) of
about 70s (50-300 keV). The time-averaged spectrum from
T0-14.6 s to T0+70.1 s is adequately fit by a power law
function with an exponential high-energy cutoff. The power law
index is -0.99 +/- 0.14  and the cutoff energy, parameterised as
Epeak, is 507 +/- 192 keV.

The event fluence (10-1000 keV) in this time interval is
(2.10 +/- 0.04)E-06 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+1.28 s in the 10-1000 keV band is
1.39 +/- 0.18 ph/s/cm^2.

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