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GCN Circular 33777

GRB 230510A: GIT optical upper limits
2023-05-12T11:26:15Z (a year ago)
Vishwajeet Swain at IIT Bombay <>
V. Swain (IITB), A. Salgundi (IITB), H. Kumar (IITB), V. Bhalerao (IITB), G.C. Anupama(IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: 

We observed the field of GRB 230510A detected by Fermi (Fermi GBM team, GCN 33751, 33766) and Swift (Eyles-Ferris et al., GCN 33752) with 0.7m GROWTH-India Telescope (GIT). GIT automatically triggered at 19:35:39 UT, i.e., 7.5 hours after the Fermi GBM trigger. We obtained 3 frames of 300s each in the r' band. We search individual images and the stacked image for an afterglow, at the position reported by P.A. Evans et al. (GCN #33756). We do not detect the optical afterglow emission that was detected by S.Q. Jiang et al., (GCN #33761). Our upper limits on the magnitude of the afterglow are:

           JD (mid)           | T_mid-T0(hrs) | Exposure (sec)   | Filter | Lim_mag (5-sigma) |
 2460075.3164274      |         7.52        |          300            |    r'    |          > 18.77            |
 2460075.32027526    |         7.62        |          300            |    r'    |          > 18.81            |
 2460075.32398713    |         7.71        |          300            |    r'    |          > 18.90            | 
 2460075.320207265  |    7.61 (mid)    | 3x300 (stacked) |    r'    |          > 19.87            |

The results are consistent with other afterglow observations reported by S.Q. Jiang et al., GCN #33761; S.Q. Jiang et al., GCN #33764; A. Belles et al., GCN #33774; R. Strausbaugh at al., GCN #33776. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at
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