//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29223 SUBJECT: GRB 210102B: MAXI/GSC detection DATE: 21/01/02 12:38:16 GMT FROM: Motoko Serino at RIKEN/MAXI C. Guo (RIKEN), M. Serino (AGU), H. Negoro, M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, R. Adachi, M. Niwano, R. Hosokawa (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, U. Goto, R. Uematsu (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source at 2021-01-02T09:03:48 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (353.323 deg, -21.086 deg) = (23 33 18, -21 05 10) (J2000) with a statistical 90% C.L. circular error region with a radius of 0.5 deg. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 238 +- 31 mCrab (2.0-4.0keV, 1 sigma error). There was no significant excess flux in the next transit at 10:36 UT with an upper limit of 20 mCrab. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29224 SUBJECT: GRB 210102B: Tiled Swift observations DATE: 21/01/02 14:40:06 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 210102B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00097 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29230 SUBJECT: GRB 210102B: Swift-XRT observations DATE: 21/01/03 13:44:24 GMT FROM: Paolo D'Avanzo at INAF - OAB D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 210102B (Guo et al. GCN Circ. 29223) in a series of observations tiled on the sky. The total exposure time is 1.3 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 406 s. The data were collected between T0+19.7 ks and T0+26.0 ks, and are entirely in Photon Counting (PC) mode. One uncatalogued X-ray source has been detected, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 353.8173 = 23:35:16.14 Dec (J2000.0): -21.0821 = -21:04:55.6 Error: 5.5 arcsec (radius, 90% conf.) Count-rate: 0.030 [+0.016, -0.012] ct s^-1 Distance: 1289 arcsec from MAXI position. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00097. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29240 SUBJECT: GRB 210102B: Assy optical observations DATE: 21/01/04 18:06:38 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), S. Belkin (IKI), V. Kim (FAI, Pulkovo Observatory), M. Krugov (FAI) report on behalf of GRB IKI FuN: We observed MAXI GRB 210102B (Guo et al., GCN 29223) with AZT-20 telescope of Assy-Turgen observatory starting on Jan. 03 (UT) 13:00:53. i.e. ~1.6 days after trigger. At the place of the only one of XRT candidates (Burrows et al., GCN 29230) in the localization area of MAXI (Guo et al., GCN 29223) we clearly detect the optical object in coordinates (J2000) 23:35:15.88 -21:04:55.5 with uncertainness of 0.6 arcsec in both coordinates. Preliminary photometry of the object is following Date UT start t-T0 Filter Exp. OT Err. UL (3sigma) (mid, days) (s) 2021-01-03 13:00:53 1.19068 r'(AB) 75*60 22.2 0.2 23.0 The photometry is based on the stars of PanSTARRS-PS1 RA DEC r' 23:35:20.67802 -21:04:16.4688 19.656 23:35:47.99017 -21:11:53.6544 17.807 At this tome we cannot confirm variability of the source. We can suggest the object might be related to GRB 210102B. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29270 SUBJECT: GRB 210102B: Assy optical afterglow identification DATE: 21/01/06 15:55:15 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), S. Belkin (IKI), V. Kim (FAI, Pulkovo Observatory), M. Krugov (FAI) report on behalf of GRB IKI FuN: We continued observations of XRT candidate (Burrows et al., GCN 29230) of MAXI GRB 210102B (Guo et al., GCN 29223) with AZT-20 telescope of Assy-Turgen observatory starting on Jan. 05 (UT) 13:00:53, i.e. ~3.2 days after trigger. At the place of the only one of XRT candidate (Burrows et al., GCN 29230) we do not detect the optical object found early (Pozanenko et al., GCN 29240). Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. OT Err. UL (3sigma) (mid, days) (s) 2021-01-05 13:00:53 3.20177 r'(AB) 76*60 n/d n/d 23.1 The photometry is based on the stars of PanSTARRS-PS1 RA DEC r' 23:35:20.67802 -21:04:16.4688 19.656 23:35:47.99017 -21:11:53.6544 17.807 We confirm the optical object reported in GCN 29240 as an afterglow of GRB 210102B. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29271 SUBJECT: GRB 210102B: further Swift-XRT observations DATE: 21/01/06 17:28:28 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, M.G. Bernardini, A. Melandri, T. Sbarrato (INAF-OAB), P.A. Evans (U. Leicester) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift-XRT team: Swift-XRT obtained further observations of the field of the MAXI-detected burst GRB 210102B (Guo et al. GCN Circ. 29223). The data were collected between T0+209.5 ks and T0+312.5 ks for a total exposure time of 2.5 ks, and are entirely in Photon Counting (PC) mode. Source 1 (Burrows et al., GCN Circ. 29230) is not detected down to a 3sigma upper limit of 0.004 ct/s. The source therefore has faded (with 2.2 sigma significance) with respect to the previous detection level (0.030 [+0.016, -0.012] ct s^-1 between T0+19.7 ks and T0+26.0 ks; Burrows et al., GCN Circ. 29230). We propose this source as the GRB X-ray afterglow, in agreement with the results of the optical observations reported by Pozanenko et al. (GCN Circ. 29270).