//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15609 SUBJECT: GRB 131225A: MAXI/GSC detection DATE: 13/12/25 11:04:12 GMT FROM: H. Negoro at Nihon U. A. Kawagoe (Chuo U.), H. Negoro (Nihon U.), M. Morii (RIKEN), T. Sakamoto (AGU), S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, R. Usui, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, Y. Nakano, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, H. Sakakibara, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team: The MAXI/GSC Nova alert system triggered a bright uncatalogued X-ray transient source on 2013-12-25 at 09:54:50 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (95.150 deg, 5.413 deg) = (06 20 36, +05 24 46) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.28 deg and 0.19 deg, respectively. The roll angle of the long axis from the north direction is 43.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 273 +- 50 mCrab (4-10keV, 1 sigma error). Without the assumption about the source constancy, we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (94.339 deg, 5.886 deg) = (06 17 21, +05 53 08) (J2000) (R.A., Dec) = (94.737 deg, 6.296 deg) = (06 18 56, +06 17 45) (J2000) (R.A., Dec) = (95.508 deg, 5.443 deg) = (06 22 01, +05 26 36) (J2000) (R.A., Dec) = (95.114 deg, 5.029 deg) = (06 20 27, +05 01 44) (J2000) There was no significant excess flux in the previous transit at 08:22 UT with an upper limit of 20 mCrab. A possibility of a new X-ray transient, e.g., X-ray nova, can not be excluded since the location is close to the Galactic plane (b = -4.5 deg). We also tentatively name this GRB 131225A as MAXI J0620+053. The next transit by MAXI/GSC will be at 11:27 UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15614 SUBJECT: GRB 131225A: MASTER-Net optical observations DATE: 13/12/26 16:29:15 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, D.Denisenko, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Sankovich Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, 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 pointed to the GRB131225A 6 hours after trigger time at 2013-12-25 15:53:40 UT. We cover full MAXI error box (A. Kawagoe et al GCN 15609) using MASTER II twin telescope in parallel mode with FOV 4 sq. degrees. Observations were made in the extremely rich field (with galactic latitude b=-4 deg). The 5-sigma upper limit has been about 19.0 mag on our first (180s exposure) image. On coadd of first 19 images with total exposure 3420 sec and middle time 2013-12-25 16:30:25 UT the 5-sigma upper limit has been 20.5 mag. Inside MAXI field of view we have detected two objects not present in USNO-B1.0 catalog with the following coordinates and unfiltered magnitudes: ID #1191735: 06 19 43.71 +04 47 37.6 (20.13m) ID #1191736: 06 17 51.08 +04 57 19.8 (20.26m) We have identified both objects with the red stars on the digitized Palomar IR plates, as well as in WISE and UKIDSS catalogs. WISE J061943.55+044738.8 (W1=14.33 W2=14.14) UGPS J061943.55+044739.1 (J=15.42 H=14.88 K=14.47) WISE J061751.09+045719.6 (W1=15.79 W2=15.46) UGPS J061751.05+045719.7 (J=18.24 H=17.40 K=17.17) Also, in error box we found 2 known minor planets (Groom and 2004 OZ). The total number of known asteroids in our FOV is 11. There is no new minor planet found in error box. The combined optical image is available here http://master.sai.msu.ru/static/GRB/GRB131225A_MAXI/GRB131225A.jpeg The message may be cited.