GCN Circular 35300

Yanting Zhang, Shaolin Xiong, Yue Huang, Shuo Xiao, Xiaoyun Zhao, Ping Wang, 
report on behalf of the GECAM team:

The short burst, GRB 231206A, has been detected by GECAM-B (Liu et al., GCN 35283
Not found
 
 
) and INTEGRAL/SPI-ACS. 
With the ETJASMIN pipeline (Energetic Transients joint analysis system for Multi-INstrument, Xiao et al.,
MNRAS, 514, 2397, 2022) and the data of GECAM-B and INTEGRAL/SPI-ACS, we did a joint location for this burst.

Firstly, we applied the Li-CCF method (Xiao et al., ApJ, 920, 43, 2021) to the high 
temporal resolution (~0.1 ms) light curve of GECAM-B and the low-latency public 50 ms 
light curve of INTEGRAL/SPI-ACS, and derived the triangulation location as the following annuli:

--------------------------------------------------------------------------------------------------
Annulus                 Ra (deg)      Dec (deg)     Radius (deg)      Radius-Error (deg, 3sigma)
GECAM-B + SPI-ACS       37.933        78.224        103.958           47.522
--------------------------------------------------------------------------------------------------

Then, we combined this triangulation location, the stand-alone location provided by GECAM-B 
(Liu et al., GCN 35283
Not found
 
 
), as well as the Earth occultation of these instruments, 
and derived a refined location, which is much smaller than the stand-alone ones. 

The center (highest probability) of this refined location is:

--------------------------------------
            RA (deg)      Dec (deg)
Center      314.648	  -20.742   
--------------------------------------

The 1-simga region of this refined location is about 295 deg^2. 

The sky map and probability healpix data of this refined location could be found at:
Sky map: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206-jointLoc-skymap-v01.png
Data file: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206A-jointLoc-healpix-v01.fits

Note that a part of the location region is below the Earth limb of GECAM-B and thus excluded.

This location may be improved.

ETJASMIN is developed for joint observation of high energy transients by the GECAM team.
We acknowledge the public data of INTEGRAL/SPI-ACS.