GRB 131026A

Klotz A., Turpin D. (IRAP-CNRS-OMP), Gendre B.,
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 131026A detected by SWIFT
(trigger 575905) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 86.9s after the GRB trigger
(13.7s after the notice). The elevation of the field decreased from
12 degrees above horizon and weather conditions
were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+86.9s to t0+146.9s : Rlim = 16.8

The second image is 30.0s exposure in tracking mode:
t0+160.5s to t0+190.5s : Rlim = 17.4

We co-added a series of exposures:
t0+160.5s to t0+451.9s : Rlim = 18.9

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=125.5580 lat=-30.3300
and the galactic extinction in R band is about 0.2 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

L. Izzo (URoma/ICRA), V. D'Elia (ASDC), P. D'Avanzo, A. Melandri  
(INAF-OAB), A. Maselli (INAF-IASFPA) report:


We have analysed 8.93 ks of XRT data for Swift Trigger 575905 (Cenko  
et al. GCN Circ. 15384
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 ). Two sources were detected at SNR>4, inside a  
region of 3 arcmin from the BAT position at the following coordinates:

Source 1 - (1RXS J010222.4+323020)
RA,Dec = 01h 02m 22.8s, +32� 30' 02.7"

Source 2
RA,Dec = 01h 02m 02.6s, +32� 30' 00.9",

with an uncertainty of 4.1" and 4.6", respectively.

Source 1 matches a catalogued X-ray source (1RXS J010222.4+323020 of  
the ROSAT/RASSFSC table is 18" away), while source 2 is an  
uncatalogued source, but below the RASS limit.

We can not say at the present time whether source 2 is fading. The  
count rate at the position of Source 2 is (4.3 +/- 1.0) x 10^-3 cts/s.  
This corresponds to an observed 0.3-10 keV flux of 1.54 x 10^-13  
erg/cm2/s (assuming a typical GRB spectrum with photon spectral index  
of 2). If we consider the Galactic absorption in this direction (5.1 x  
10^20 cm^-2; Kalberla et al. 2005) this corresponds to an unabsorbed  
flux of 1.78 x 10^-13 erg/cm2/s.

The results of the XRT-team automatic analysis are available at:
http://www.swift.ac.uk/possible_GRBs/00575905

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

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D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa,
Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, NAOJ),
S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 1301026A (Swift Trigger 575905) (Cenko et al., GCNC
15384) with the optical three color (g', Rc and Ic) CCD camera attached to the
MITSuME 50cm telescope of Okayama Astrophysical Observatory and the Murikabushi
1m telescope of Ishigakijima Astronomical Observatory.

We did not find any new point source within the BAT error circle (Cenko et al.,
GCNC 15384) in all the three bands.

Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for
flux calibration.

Okayama Astrophysical Observatory:
The observation started on 2013-10-26 10:01:09 UT (~3.4 h after the burst).
T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
0.24326    12:29:49    6300.0    >19.7  >19.6  >18.6
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


Ishigakijima Astronomical Observatory:
The observation started on 2013-10-26 13:13:44 UT (~6.6 h after the burst).
T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
0.30110    13:53:07    3360.0    >21.6  >21.0  >20.4
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

A. Volnova (IKI), R. Inasaridze (AAO), G. Inasaridze (AAO), V.
Zhuzhunadze (AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko 
(IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of Swift Trigger 575905/GRB 131026A (Cenko et al., 
GCN 15384
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 )  with AS-32 telescope of Abastumani Observatory starting 
Oct., 26 (UT) 21:06:35. We obtained several unfiltered images with 
exposures of 180 s. We investigated stacked image and found that both 
XRT sources (Izzo et al., GCN 15388
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 ) coincide with known optical 
sources, i.e.

source 1 (XRT) = SDSS J010222.74+323005.0 (01:02:22.75 +32:30:05.0)
source 2 (XRT) = TYC 2281-1221-1 (01 02 02.468 +32 30 01.53)

Within BAT error circle (Cenko et al., GCN 15384
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 ) we found a point-like 
source which is not presented in SDSS catalog. Coordinates of the source 
are (J2000) RA=   01 02 14.64, Dec = +32 30 35.7  with uncertainties of 
0.2 arcsec in both coordinates. The details of the photometry of the 
source  are the following:

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

21:06:35   0.64270     None   32x180   21.67 +/- 0.08  22.6

The photometry is based SDSS stars, R (gri -> R transformations by
Lupton 2005):

SDSS id                   R(Lupton)
J010212.32+323137.9       18.988
J010208.62+323107.7       17.448
J010155.76+322851.8       17.317

We subdivide total number of images in two combined images and compare 
astrometry and photometry of the two combined images. One can conclude 
that the upper limit of a proper motion of the source is 3 arcsec per 50 
minutes, and one can marginally suggest that brightness of the source is 
increased at ~0.3m between the two combined images.

Finding chart can be found in 
http://grb.rssi.ru/GRB131026A_Swift_575905/GRB131026A_chart2.png

Additional observations in optic and X-ray are encouraged.