Gamma-ray Burst 210222A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/MAXI NOTICE
NOTICE_DATE:     Mon 22 Feb 21 19:30:49 UT
NOTICE_TYPE:     MAXI Unknown Source Position
EVENT_ID_NUM:      9267547957
EVENT_RA:        352.69d {+23h 30m 46s} (J2000),
                 352.97d {+23h 31m 53s} (current),
                 352.03d {+23h 28m 08s} (1950)
EVENT_DEC:       -28.81d {-28d 48' 31"} (J2000),
                 -28.69d {-28d 41' 31"} (current),
                 -29.08d {-29d 05' 05"} (1950)
EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX:      690.0 +- 0.0 [mCrab]
EVENT_DATE:      19267 TJD;    53 DOY;   21/02/22
EVENT_TIME:      57569.00 SOD {15:59:29.00} UT
EVENT_TSCALE:    10s
EVENT_EBAND:     Low, 2-4 keV
SUN_POSTN:       336.27d {+22h 25m 05s}   -9.89d {-09d 53' 39"}
SUN_DIST:         24.47 [deg]
MOON_POSTN:       98.91d {+06h 35m 39s}  +25.01d {+25d 00' 37"}
MOON_DIST:       114.92 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:       22.83,-72.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      341.31,-23.44 [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:     Mon 22 Feb 21 19:40:20 UT
NOTICE_TYPE:     MAXI Unknown Source Position
EVENT_ID_NUM:      9267547957
EVENT_RA:        353.13d {+23h 32m 31s} (J2000),
                 353.41d {+23h 33m 38s} (current),
                 352.47d {+23h 29m 52s} (1950)
EVENT_DEC:       -29.46d {-29d 27' 49"} (J2000),
                 -29.35d {-29d 20' 48"} (current),
                 -29.74d {-29d 44' 23"} (1950)
EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX:      389.0 +- 0.0 [mCrab]
EVENT_DATE:      19267 TJD;    53 DOY;   21/02/22
EVENT_TIME:      57569.00 SOD {15:59:29.00} UT
EVENT_TSCALE:    10s
EVENT_EBAND:     Low, 2-4 keV
SUN_POSTN:       336.28d {+22h 25m 07s}   -9.89d {-09d 53' 31"}
SUN_DIST:         25.20 [deg]
MOON_POSTN:       99.01d {+06h 36m 01s}  +25.01d {+25d 00' 43"}
MOON_DIST:       114.81 [deg]
MOON_ILLUM:      78 [%]
GAL_COORDS:       20.64,-72.49 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      341.38,-24.20 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.

GCN Circular #29543
M. Nakajima (Nihon U.), M. Serino (AGU), Y. Kawakubo (LSU), H. Negoro, 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, Y. Goto, R. Uematsu (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), M. Sugizaki (NAOC) report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 2021-02-22T15:59:19 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (353.129 deg, -29.464 deg) = (23 32 30, -29 27 50) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.11 deg and 0.04 deg, respectively. The roll angle of long axis from the north direction is 90.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 389 +- 38 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 14:26 UT with an upper limit of 20 mCrab.
GCN Circular #29553
P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), and the CALET collaboration:
At 15:57:23.469 UTC on 22 February 2021, the CALET Gamma-ray Burst Monitor (CGBM) triggered on long GRB 210222A (http://cgbm.calet.jp/cgbm_trigger/flight/1298044600/), which was also detected by the MAXI/GSC at T0(CGBM)+116 s (Nakajima et al., GCN Circ. 29543). The burst signal was seen by all CGBM detectors.
The burst light curve shows a FRED-like pulse which starts at T+0.6 sec, peaks at T+7.5 sec, and ends at T+87.3 sec. The T90 and T50 durations measured by the SGM data are 71.4 +- 11.5 sec and 33.5 +- 4.4 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1298044600/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.
GCN Circular #29564
D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin, A. Ridnaya, A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long GRB 210222A (MAXI/GSC detection: Nakajima et al., GCN 29543; CALET Gamma-Ray Burst Monitor detection: Marrocchesi et al., GCN 29553) was detected by Konus-Wind (KW) in the waiting mode starting from ~T0 = 57443.990 (15:57:23.990) UT (or ~2 minutes before the MAXI trigger).
A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band reveals a ~30 sigma count rate increase over background in the interval from ~T0 to ~T0+177 s. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB210222A/
Modeling the KW 3-channel time-integrated spectrum (measured from T0+0.115 s to T0+176.755 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.33(-0.11,+0.15) and Ep = 317(-72,+108) keV.
A CPL fit to the spectrum near the peak count rate, measured from T0+0.115 s to T0+14.835 s, gives alpha -0.48(-0.14,+0.15), and Ep of 375(-40,+40) keV.
In the 10 keV -10 MeV band, the total burst fluence is (4.2 ą 0.6)x10^-5 erg/cm^2, and the 2.944 s peak energy flux is (9.3 ą 0.8)x10^-7 erg/cm^2.
All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.

Back to JG's homepage

Jochen Greiner, last update: 24-Feb-2021 [Disclaimer]