GRB 120127A

S. Song, M. Morii (Tokyo Tech), H. Negoro, F. Suwa (Nihon U.), M. Serino, S. Nakahira (RIKEN),
S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA),
T. Mihara, M. Sugizaki, T. Yamamoto, T. Sootome, M. Matsuoka (RIKEN), 
N. Kawai, K. Sugimori, R. Usui, T. Toizumi, Y. Aoki (Tokyo Tech),
A. Yoshida, K. Yamaoka (AGU),
H. Tsunemi, M. Kimura, H. Kitayama (Osaka U.), 
M. Nakajima, M. Asada, H. Sakakibara (Nihon U.), 
Y. Ueda, K. Hiroi, M. Shidatsu (Kyoto U.),
Y. Tsuboi, T. Matsumura, K. Yamazaki (Chuo U.)
M. Yamauchi, Y. Nishimura, T. Hanayama (Miyazaki U.) 
report on behalf of the MAXI team:

MAXI/GSC triggered at 2012-01-27 04:21:52 UT on an uncatalogued X-ray transient source.
The transient emission lasted for about 10 seconds
within the 50 second long triangular transit response of
MAXI/GSC. We identify this event as GRB 120127A.

Assuming that the source flux was constant over the transit,
we obtain a statistical 90% C.L. elliptical error region centered on

(R.A., Dec) = (139.14 deg, 15.88 deg) = (09 16 34, +15 52 51)(J2000)

with long and short radii of 0.74 deg and 0.52 deg, respectively.
The position angle of long axis is 53.7 deg.
There is additional systematic uncertainty of 0.1 deg (90% containment radius).

Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:

 (R.A., Dec) = (138.12 deg, 15.61 deg) = (09 12 29, +15 36 32)(J2000)
 (R.A., Dec) = (138.95 deg, 14.87 deg) = (09 15 47, +14 52 29)(J2000)
 (R.A., Dec) = (140.82 deg, 16.80 deg) = (09 23 16, +16 48 02)(J2000)
 (R.A., Dec) = (140.00 deg, 17.54 deg) = (09 20 01, +17 32 09)(J2000)

The X-ray flux averaged over the scan was 48 +- 21  mCrab (4-10 keV, 1 sigma error).

Follow-up observations are encouraged.

E. Gorbovskoy, V. Lipunov,  V.Kornilov, D.Kuvshinov, 
A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov,  A.Kuznetsov,
D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov,
A.Sankovich, S. Shurpakov
Moscow State University,  Sternberg Astronomical Institute


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

  V.Krushinski, I.Zalozhnich, A. Popov
Ural State University, Kourovka

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

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



  MASTER II  robotic double telescope (FOW=2x4 square degrees, 
http://observ.pereplet.ru) located 
in Tunka was pointed to the  GRB120127A (MAXI/GSC, Song et al., GCN Circ 
12901
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 ) 9h 30 min after GRB time at 2012-01-27 04:21:52 UT  in two polarizations. 
On our  images we haven`t found optical transient
within error-box (Song et al., GCN Circ 12901
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 ).
The delay is due to the MAXI/GSC ground reduction.

    Date       UT         UT           Exp     Coadd      Limit
             Start     Mean Time
2012-01-27 13:51:59   13:53:29      180s       no         18.9
2012-01-27 13:51:59   13:58:40      900s       yes        19.9




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S. B. Cenko (UC Berkeley), E. O. Ofek (Weizmann Institute), and P. E.
Nugent (LBNL/UC Berkeley) report on behalf of a larger collaboration:

We have imaged the location of the MAXI GRB120127A (Song et al., GCN
12901
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 ) with the Palomar 48 inch Oschin Schmidt telescope as part of the
Palomar Transient Factory.  Observations began at 3:41 UT on 28 January
2012 (~ 23.3 hours after the MAXI trigger) and cover ~ 90% of the MAXI
error localization.

By comparing sources detected in our images with the USNO-B1 catalog,
2MASS point source catalog, and the Digital Palomar Optical Sky Survey
archival images, we find no new sources within the MAXI error
localization (aside from a number of known minor planets).  The limiting
magnitude of our imaging is R >~ 19.5 mag (calculated with respect to
field stars from the USNO-B catalog).