Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 30560

Subject
GRB 210730A: TNG optical observations
Date
2021-07-31T02:05:32Z (3 years ago)
From
Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>
P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), M. Della Valle (INAF-OACN) A. Melandri (INAF-OAB), A. Rossi (INAF-OAS), 
G. Tagliaferri (INAF-OOAB), A. Harutyunyan, D. Carosati (INAF-TNG) on behalf of the CIBO collaboration report:

We observed the field of GRB 210730A (Sonbas et al., GCN Circ. 30548; Prasad et al., GCN Circ. 30555; Wood et al., GCN Circ. 30577) 
with the Italian 3.6m TNG telescope equipped with the optical camera DOLORES. A series of images were obtained with the r-sdss filter 
on 2021-07-30 from 21:41:57 UT to 22:08:38 UT (i.e. about 17 hours after the burst).  

At the edge of the XRT error circle (https://www.swift.ac.uk/xrt_positions/01062150/) we detect a faint optical source at the following 
position (J2000): 
RA: 09:58:21.96
Dec: +69:41:23.6
(+/- 1.0"). 


With preliminary photometry, carried out using a small aperture to minimise contamination from a nearby bright star, we derive the following 
magnitude:
r = 22.7  +/- 0.2 

(AB; calibrated against the SDSS catalogue). 
In our co-added image we reach a limiting magnitude of r ~ 23.5 (AB, 3sigma c.l.). 

We note that the same source is visible in archival Pan-STARRS images. Using a common set of reference stars and carrying out differential 
photometry on TNG and Pan-STARRS images we find no evidence for a change in magnitude of this source. 

Therefore, this source is likely not related to GRB 210730A. Alternatively, it can be the GRB host galaxy.
Looking for U.S. government information and services? Visit USA.gov