Gamma-ray Burst 210109A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sat 09 Jan 21 11:39:06 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:      9223337892
  EVENT_RA:         62.25d {+04h 09m 00s} (J2000),
                    62.53d {+04h 10m 07s} (current),
                    61.59d {+04h 06m 21s} (1950)
  EVENT_DEC:        +5.03d {+05d 01' 37"} (J2000),
                    +5.08d {+05d 04' 52"} (current),
                    +4.90d {+04d 53' 45"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      188.0 +- 0.0 [mCrab]
  EVENT_DATE:      19223 TJD;     9 DOY;   21/01/09
  EVENT_TIME:      32610.00 SOD {09:03:30.00} UT
  EVENT_TSCALE:    30s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:       291.03d {+19h 24m 08s}  -22.03d {-22d 01' 40"}
  SUN_DIST:        130.17 [deg]
  MOON_POSTN:      238.54d {+15h 54m 09s}  -18.64d {-18d 38' 06"}
  MOON_DIST:       165.90 [deg]
  MOON_ILLUM:      17 [%]
  GAL_COORDS:      186.64,-32.49 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       61.20,-15.68 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN NOTICE
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sat 09 Jan 21 11:41:06 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:      9223337892
  EVENT_RA:         62.00d {+04h 08m 01s} (J2000),
                    62.28d {+04h 09m 07s} (current),
                    61.34d {+04h 05m 22s} (1950)
  EVENT_DEC:        +4.68d {+04d 40' 44"} (J2000),
                    +4.73d {+04d 44' 01"} (current),
                    +4.55d {+04d 32' 49"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      108.0 +- 0.0 [mCrab]
  EVENT_DATE:      19223 TJD;     9 DOY;   21/01/09
  EVENT_TIME:      32610.00 SOD {09:03:30.00} UT
  EVENT_TSCALE:    30s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:       291.03d {+19h 24m 08s}  -22.03d {-22d 01' 40"}
  SUN_DIST:        129.79 [deg]
  MOON_POSTN:      238.56d {+15h 54m 14s}  -18.64d {-18d 38' 28"}
  MOON_DIST:       165.63 [deg]
  MOON_ILLUM:      17 [%]
  GAL_COORDS:      186.80,-32.89 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       60.88,-15.97 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN Circular #29282
  R. Uematsu (Kyoto U.), H. Negoro (Nihon U.), M. Serino (AGU), 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 (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 UT 09:03:26 on 2021 January 9. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (62.003 deg, 4.679 deg) = (04 08 00, +04 40 44) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.28 deg and 0.25 deg, respectively. The roll angle of the long axis from the north direction is 58.0 deg counterclockwise. Without assumptions on the source flux constancy, we obtain a rectangular error box for the transient source with the following corners:

  (60.844, 3.548) deg = (04 03 22, +03 32 52) (J2000) 
  (61.261, 3.251) deg = (04 05 02, +03 15 03) (J2000) 
  (62.919, 5.559) deg = (04 11 40, +05 33 32) (J2000) 
  (62.501, 5.857) deg = (04 10 00, +05 51 25) (J2000)
  

  There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
  The X-ray flux averaged over the scan was 108 +- 23 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at UT 07:30 and in the next transit at 10:36 with an upper limit of 20 mCrab for each.