TITLE:   GCN CIRCULAR
NUMBER:  29276
SUBJECT: GRB 201227A: ASIM observation
DATE:    21/01/07 14:29:38 GMT
FROM:    Martino Marisaldi at U of Bergen, Norway  <martino.marisaldi@uib.no>

M. Marisaldi (University of Bergen), A. Mezentsev (University of Bergen), 
N. Østgaard (University of Bergen), V. Reglero (University of Valencia) 
and T. Neubert (DTU Space) report on behalf of the ASIM Team:

At 15:14:07.380 UT on 27 December 2020, the Atmosphere-Space Interactions Monitor (ASIM)
mission triggered on the very short and bright GRB 201227A 
(AGILE detection: Ursi et al., GCN Circ. 29179; IPN triangulation: Svinkin et al., GCN Circ. 29182;
Swift observations: Evans, GCN Circ. 29184; Evans, GCN Circ. 29185; D’Elia et al., GCN Circ. 29202;
Insight-HXMT/HE detection: Xiao et al., GCN Circ. 29187; Konus-Wind observation:  Svinkin et al., GCN Circ. 29196;
Fermi GBM observation: Lesage et al., GCN Circ. 29206; GRAWITA VST observation: Izzo et al., GCN Circ. 29207
Chilescope observation:  Belkin et al., GCN Circ. 29208)

Photon by photon data with <1 microsecond time resolution have been
collected for a time interval of two seconds centered at the trigger time.
As seen by the Modular X- and Gamma-Ray Sensor (MXGS) onboard ASIM
the burst consists of a single emission episode about 60 ms in duration, with evidence of time variability. 
The emission is detected in the MXGS High Energy Detector (HED), 
sensitive in the range 0.3 to >30 MeV.  
Significant emission is observed up to about 3 MeV. 
The MXGS Low Energy Detector (LED), sensitive in the range 0.05 to 0.4 MeV, 
was not active at trigger time.

ASIM is an ESA mission onboard the International Space Station dedicated to the 
observation of Terrestrial Gamma-ray Flashes (TGFs) and Transient Luminous Events (TLEs) 
operative since June 2018 (Neubert et al., Space Sci Rev (2019) 215:26 
https://doi.org/10.1007/s11214-019-0592-z <https://doi.org/10.1007/s11214-019-0592-z>  ). 
The payload includes the Modular X- and Gamma-Ray Sensor (MXGS) 
(Østgaard et al., Space Sci Rev (2019) 215:23 https://doi.org/10.1007/s11214-018-0573-7 <https://doi.org/10.1007/s11214-018-0573-7>  ), 
and the the Modular Multispectral Imaging Array  (MMIA) 
(Chanrion et al., Space Sci Rev (2019) 215:28 https://doi.org/10.1007/s11214-019-0593-y <https://doi.org/10.1007/s11214-019-0593-y>  ). 
The ASIM Science Data Centre (ASDC) website is https://asdc.space.dtu.dk/ <https://asdc.space.dtu.dk/>