TITLE: GCN CIRCULAR NUMBER: 30908 SUBJECT: GRB 210927A: GIT optical follow-up of ZTF21acdwctm. DATE: 21/10/01 03:59:51 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com> H. Kumar(IITB), V. Bhalerao(IITB), J. Stanzin (IAO), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team and the GROWTH Collaboration: We observed ZTF21acdwctm reported by Shreya Anand et al. (GCN 30893), with 0.7m GROWTH-India Telescope (GIT). We obtained multiple exposures in the SDSS r' filter spanning over 3 nights i.e. 2021-09-28, 2021-09-29, and 2021-09-30. We clearly detected the afterglow in our stacked images on all 3 nights. The photometric results follow as: ------------------------------------------------------------------- JD (mid) | T_mid-T0(hrs) | Filter | Magnitude (AB) | ------------------------------------------------------------------- 2459486.16719 | 39.28 | r' | 21.32 +/- 0.07 2459487.12169 | 62.19 | r' | 21.59 +/- 0.09 2459488.13340 | 86.47 | r' | 21.92 +/- 0.08 ------------------------------------------------------------------- Based on GIT photometry we can conclude that the candidate is decaying with a rate of ~0.3 mag/day. A further follow-up of this candidate is highly 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/.