GRB 091202

S. Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), C.Ferrigno, 
E.Bozzo, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf 
of the IBAS Localization Team report:

A  GRB with duration of about 50  s has been detected by IBAS in
IBIS/ISGRI data at 23:10:12 UT on December 2nd.

The refined coordinates (J2000) are:

RA: 138.8312 [degrees]  
DEC: 62.544  [degrees]

with an uncertainty of 2.5 arcmin (90% c.l.).

A plot of the light curve will be posted at

http://ibas.iasf-milano.inaf.it/IBAS_Results.html

This message can be cited.

C.G. Mundell (Liverpool, JMU) reports on behalf of a larger collaboration:

"The 2-m Liverpool Telescope robotically followed up GRB091202
(INTEGRAL trigger 5957; Mereghetti et al. GCN 10234
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 ) 60.93 min after
the GRB trigger time.

Preliminary analysis shows no uncatalogued source within a 4.6-arcmin 
diameter error box centred on the INTEGRAL position to a limiting 
magnitude i'~19 mag (vs USNOB1).

We note the presence of a faint galaxy centred at the INTEGRAL position:
http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587737809576592135

This message may be cited"

Klotz A. (CESR-OMP), Gendre B. (IASF),
Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 091202 detected by INTEGRAL
(trigger 5957) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 35s after the GRB trigger.
The elevation of the field increased from
45 degrees above horizon and weather conditions
were poor (full moon at 50 deg).

The date of trigger : t0 = 2009-12-02T23:10:12
(according to Mereghetti et al. GCNC 10234).

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+35s to t0+95s : R > 13.0

The second image is 30.0s exposure in tracking mode:
t0+114s to t0+144s : R > 15.3

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction
(estimated to be 0.13 magnitudes in R band).
N.B. Galactic coordinates are lon=152.2 lat=+40.2

L. Vetere (PSU), P.A. Evans and M.R. Goad (U. Leicester) report
on behalf of the Swift-XRT team:

Using 1511 s of XRT Photon Counting mode data and 1 UVOT
images, 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 =138.83400, 62.54950 which is equivalent to:

RA (J2000):  09 15 20.17
Dec (J2000): +62 32 58.1

with an uncertainty of 3.4 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 is an official product of the Swift-XRT team.

A. de Ugarte Postigo (INAF-OAB), A.J. Castro-Tirado, M. Jelinek,
J. Gorosabel, S. Guziy (IAA-CSIC) and R. Barrena-Delgado (IAC)
report on behalf of a larger collaboration:

"We have observed the error box of the INTEGRAL GRB 091202
(Mereghetti et al. GCN 10234
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 ) in optical using the 0.8m IAC80
telescope and in NIR using the 1.5m TCS telescope, both located
in Teide Observatory (Spain).

Optical observations began at 1:26 UT of the 3rd Dec 2009 and
included V, R and I imaging. We do not detect any new source
within the XRT error box (Vetere et al. GCN10239
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 ). In particular
in a 600s I band image with mean epoch 3.07 h after the burst
onset we do not detect any new source down to a 3-sigma limiting
magnitude of I > 19.9 as compared to USNO-B1.0 star 1525-0212637
for which we assume a magnitude of I = 18.26.

NIR observations starting at 04:03 UT were obtained with J, H
and K filters, with a total of 1000s integration each. We do not
detect any new source within the XRT error box. In particular,
we obtain a 3-sigma limiting magnitude of K > 17.0 5.12 h after
the burst as compared with the 2MASS catalogue.

This message may be cited."

C. Guidorzi (U. Ferrara), C.G. Mundell, D. Bersier, Z. Cano,
N.R. Clay, S. Kobayashi, A. Melandri, C.J. Mottram, R.J. Smith,
I.A. Steele (Liverpool JMU), A. Gomboc (U. Ljubljana) report
on behalf of a large collaboration:

On 2009 December 3 at 00:11:21 UT the 2-m Liverpool Telescope
automatically began observing the INTEGRAL GRB 091202
(Mereghetti et al., GCN Circ. 10234
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 ; Mundell GCN Circ 10235
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 )
using the r', i' and z' filters, corresponding to 1.02 hours
after the burst.

Inside the XRT error circle (Vetere et al. GCN Circ. 10239
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 )
we do not detect any source at the following limiting
magnitudes:

Mid time from    Total Exp   Filter    Magnitude
trigger (hr)     (s)
------------------------------------------------
1.48             360         z'        > 19.0
1.61             720         i'        > 20.7
1.49             720         r'        > 20.4
------------------------------------------------

Magnitudes have been calibrated from the following nearby
SDSS stars:

RA            Dec         z'       i'      r'
-----------------------------------------------
138.81006    +62.53208   15.16    15.24   15.41
138.82579    +62.53708   18.73    18.73   18.90
-----------------------------------------------

A. Breeveld (MSSL/UCL) and L. Vetere (PSU) report on behalf of the 
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 091202 
2363 s after the Integral trigger (Mereghetti et al., GCN Circ. 
10234
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 ). No new sources are found at the XRT position (Vetere et al., 
GCN Circ. 10239
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 ) in the initial UVOT exposures. Preliminary 3-sigma 
upper limits using the UVOT photometric system (Poole et al. 2008, 
MNRAS, 383, 627) for the initial exposures are:

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

white             3120         3869          738         >21.7
v                 3876         4357          473         >19.5
u                 2363         3113          738         >20.9

The values quoted above are not corrected for the Galactic extinction 
due to the reddening of E(B-V) = 0.051 in the direction of the burst 
(Schlegel et al. 1998).

L. Vetere (PSU) reports on behalf of the Swift-XRT team:

We have analysed 5.6 ks of XRT data for GRB 091202 (Mereghetti et al.
GCN Circ. 10234
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 ) from 2364 s to 26.9 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Vetere et al. (GCN. Circ 10239).

The light curve is decaying but we do not have enough data to estimate
the decay slope and no more observations are planned at this time.

The spectrum comprises only 27 photons, but it can be fitted with an  
absorbed
power-law with a photon spectral index of 2.2 (+0.9 -0.8).  The best- 
fitting
absorption column is 2.0 (+2.9, -1.2) x 10^21 cm^-2, in excess of the  
Galactic
value of 3.9 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to  
observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this  
spectrum
is 4.2 x 10^-11 (6.4 x 10^-11) erg cm^-2 count^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020123.

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

A. de Ugarte Postigo (INAF-OAB), A.J. Castro-Tirado, J. Gorosabel, M. 
Jel�nek, S. Guziy (IAA-CSIC), A. Cabrera-Lavers, D. Garc�a, G. G�mez 
(GTC/IAC), G. Bergond (CAHA), D. P�rez-Ram�rez (Univ. de Ja�n), R. 
Cuniffe (IAA-CSIC) and P. Kub�nek (IAA-CSIC, U. Valencia) report on 
behalf of a larger collaboration:

"We have observed the field of the INTEGRAL GRB 091202  (Mereghetti et 
al. GCN 10234
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 ) using OSIRIS at the 10.4m Gran Telescopio Canarias (GTC) 
at the Observatorio del Roque de los Muchachos of the Instituto de 
Astrof�sica de Canarias, in the island of La Palma. Observations were 
carried out between 04:55 and 05:23 UT on 4 December 2009 (~1.25 days 
after the burst). The observation consisted of 5x30s exposures in r, i 
and z bands. Addtional near-IR observations were obtained in with 
Omega2000 at the 3.5m telescope at the German-Spanish Calar Alto 
Observatory in J, H and K' bands between 01:06 and 04:46 UT.

Within the XRT error circle (Vetere et al. GCN 10239
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 ) we detect two 
sources, one point-like and one apparently extended in all three GTC 
frames. Only one source (point-like) shows up in the near-IR frame, 
which appears to be superimposed to the extended one seen in the 
optical. This will imply a strong red colour (r-H >= 4) typical of GRB 
afterglows (Gorosabel et al. 2002, A&A 384, 11). Hence, we identify this 
source as the likely afterglow to GRB 091202, at coordinates (J2000.0):

R.A.:  09 15 19.75
Dec.: +62 32 59.0

with a 0".5 astrometry error.

At a mean epoch of 1.25 days after the burst, we measure for it a 
magnitude of r = 23.7 � 0.1. From the nIR observations we measure H = 
19.7 � 0.2. at a mean epoch 1.21 days after the burst. For the optical 
photometry we used the SDSS star located at coordinates R.A.: 09 15 
21.23, Dec: +62 32 33.4 (J2000.0) for which we assume a magnitude of r = 
21.27. The nIR images were calibrated against a 2MASS star at 
coordinates R.A.: 09 15 14.41, Dec: +62:31:55.5 (J2000.0) with H = 13.94.

Based on the optical GTC image, at this moment we cannot rule out that 
the optical flux arises from an underlying somehow extended blue galaxy 
whereas the highly extincted afterglow is only observed in the nIR. A 
figure showing the optical & nIR images of the likely afterglow to GRB 
091202 can be found at:  http://www.iaa.es/~gss/GRB091202

This message may be quoted."