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GCN Circular 31017

Subject
GRB 211024A: Swift-XRT source 4 is not an afterglow.
Date
2021-10-28T12:09:28Z (3 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar(IITB), S. Joharle (IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G.
C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:

We continued the observation of X-ray source (#4) by Swift-XRT ToO
observations (M. Perri et al. GCN # 31013), a candidate for the afterglow
of Fermi GBM GRB 211024A (GCN 30962), A. Tohuvavohu et al., (GCN #31006),
with 0.7m GROWTH-India Telescope (GIT). We obtained multiple exposures of
300 sec each in the g', r' and i' filters. The photometric results follow
as:

-------------------------------------------------------------------

 JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |

-------------------------------------------------------------------

 2459515.167376 | 3.60 |  g' |  20.25 +/- 0.06

 2459515.136124 | 3.57 |  i' |  19.68 +/- 0.057

 2459515.146851 | 3.58 |  r' |  19.85 +/- 0.034

-------------------------------------------------------------------
Comparing magnitude in r' filter with our previous photometry reported in
H. Kumar et al., (GCN #31014), we conclude that the source is not evolving
and is not an afterglow of the GRB 211024A.

We did not detect sources #3,#5,#6 of Swift-XRT ToO observations (M. Perri
et al. GCN # 31013) up to the following upper limits:-

-------------------------------------------------------------------

 JD (Start) | T_start-T0(days) | Filter | upper limit |

-------------------------------------------------------------------

 2459514.2374 | 2.67 | r' | > 20.26

 2459515.1674 | 3.60 | g' | > 21.03

 2459515.1361 | 3.58 | i' | > 20.51

 -------------------------------------------------------------------

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/.
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