TITLE:   GCN CIRCULAR
NUMBER:  39307
SUBJECT: GRB250101A: Radio upper limits from GMRT observations
DATE:    25/02/13 03:05:42 GMT
FROM:    Arvind Balasubramanian <arvind6895@gmail.com>

A. Balasubramanian (IIA), A.P. Saikia (IITB), V. Swain (IITB), G.C. Anupama (IIA), S. Barway (IIA), V. Bhalerao (IITB) report

We observed the field of the gamma ray burst GRB250101A (Page et al. GCN 38752, Li et al. GCN 38753, Mohan et al. GCN 38754, Zhu et al. GCN 38755, Budnev et al. GCN 38756, Wu et al. GCN 38758, Odeh et al. GCN 38763) with the Giant Metrewave Radio Telescope (GMRT) under the DDT (PI: A. Balasubramanian, ddtC419) on 8th February 2025 in band 5 (1.3 GHz) for about 2 hours starting at 13:30 hours UTC.

We do not detect any significant radio emission at the position of the optical counterpart (Li et al. GCN 38753). We used 3C48 for the flux calibration and J0238+166 for complex gain and phase calibration. The CASA calibration and imagining CAPTURE-CASA6 pipline was used for data calibration and imaging. We compute a 3-sigma upper limit of ~150 uJy at 1.3 GHz. 

We thank the GMRT Time Allocation Committee for accepting our DDT proposal and GMRT staff that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.