TITLE: GCN CIRCULAR NUMBER: 31014 SUBJECT: GRB 211024A: Possible afterglow candidate from GIT DATE: 21/10/27 11:35:56 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay harshkosli13@gmail.com
H. Kumar(IITB), V. Swain (IITB), U. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:
We observed GRB 211024A detected by Fermi GBM (GCN 30962), localisation further refined by Swift/BAT-GUANO
A. Tohuvavohu et al., (GCN #31006), with 0.7m GROWTH-India Telescope (GIT). We obtained 2 exposures of 300 sec each in the r' filter, separated by ~15 min. We detected a potential candidate in our subtracted image at R.A.= 1:52:46.98 , DEC.= -7:00:27.30. This is coincident with an X-ray source (#4) by Swift-XRT ToO observations (M. Perri et al. GCN # 31013). The photometric results follow as:
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JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |
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2459514.2264 | 2.66 | r' | 19.83 +/- 0.038|
2459514.2373 | 2.67 | r' | 19.87 +/- 0.046 |
------------------------------------------------------------------- There was an underlying source at the position of the target in the raw image which was subtracted using reference images from PanSTARRS. The source magnitude is 17.86 mag in the r band with phot_z = 0.2108 +/- 0.02 (SDSS Release 12: Alam+, 2015). This may be the host galaxy of the GRB. There is no minor planet at the location of the candidate in MPC. The gap between exposures was not sufficient to measure any decay. Further observations are planned. Follow-up observations for this source are strongly encouraged.
The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT) 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 operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.