Gamma-ray Burst 230220A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Notice
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Tue 21 Feb 23 06:19:49 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:      9995289617
  EVENT_RA:        346.66d {+23h 06m 39s} (J2000),
                   346.95d {+23h 07m 47s} (current),
                   346.04d {+23h 04m 10s} (1950)
  EVENT_DEC:       +18.55d {+18d 33' 00"} (J2000),
                   +18.68d {+18d 40' 31"} (current),
                   +18.28d {+18d 16' 46"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      11.0 +- 0.0 [mCrab]
  EVENT_DATE:      19995 TJD;    51 DOY;   23/02/20
  EVENT_TIME:      32161.00 SOD {08:56:01.00} UT
  EVENT_TSCALE:    10s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:       334.33d {+22h 17m 19s}  -10.63d {-10d 38' 05"}
  SUN_DIST:         31.84 [deg]
  MOON_POSTN:      348.63d {+23h 14m 31s}   -9.08d {-09d 04' 48"}
  MOON_DIST:        27.81 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:       90.98,-37.73 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      355.41, 22.26 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.  
  COMMENTS:        WARNING: Message received with negative flux value(s).
  

• GCN Circular #33352
  S. Nawa (Chuo U.), H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), Y. Tsuboi, J. Kohara, S. Urabe, N. Nemoto (Chuo U.), M. Shidatsu, M. Iwasaki (Ehime U.), N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA), Y. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, K. Inaba, Y. Nakatani (Kyoto U.), M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC), W. Iwakiri (Chiba U.) report on behalf of the MAXI team:
  The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 08:55:58 UT on 20 Feb 2023. Assuming that the source flux was constant over the transit, we obtain the source position at
  (R.A., Dec) = (346.565 deg, 18.607 deg) = (23 06 15, +18 36 25) (J2000)
  with a statistical 90% C.L. elliptical error region with long and short radii of 0.22 deg and 0.19 deg, respectively. The roll angle of long axis from the north direction is 153.0 deg counterclockwise. Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners.

  (196.900, -21.911) deg = (13 07 36, -21 54 39) (J2000)
  (196.998, -22.143) deg = (13 07 59, -22 08 34) (J2000)
  (198.373, -21.637) deg = (13 13 29, -21 38 13) (J2000)
  (198.273, -21.406) deg = (13 13 05, -21 24 21) (J2000)
  

  There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 182 +- 28 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 07:22 UT with an upper limit of 20 mCrab.
• GCN Circular #33367
  S. Nawa (Chuo U.), H. Negoro, M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), Y. Tsuboi, J. Kohara, S. Urabe, N. Nemoto (Chuo U.), M. Shidatsu, M. Iwasaki (Ehime U.), N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA), Y. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, K. Inaba, Y. Nakatani (Kyoto U.), M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC), and W. Iwakiri (Chiba U.) report on behalf of the MAXI team:
  Because the error box information for GRB 230220A reported in GCN #33352 was incorrect, we correct it as follows.
  The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 08:55:58 UT on 20 Feb 2023. Assuming that the source flux was constant over the transit, we obtain the source position at
  (R.A., Dec) = (346.565 deg, 18.607 deg) = (23 06 15, +18 36 25) (J2000)
  with a statistical 90% C.L. elliptical error region with long and short radii of 0.22 deg and 0.19 deg, respectively. The roll angle of long axis from the north direction is 153.0 deg counterclockwise. Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners.

  (345.720, 19.547) deg = (23 02 52, +19 32 49) (J2000)
  (345.464, 19.290) deg = (23 01 51, +19 17 23) (J2000)
  (347.309, 17.634) deg = (23 09 14, +17 38 02) (J2000)
  (347.566, 17.889) deg = (23 10 15, +17 53 20) (J2000)
  

  There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 182 +- 28 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 07:22 UT with an upper limit of 20 mCrab.