[vsnet-grb-info 28282] GRB 210704A: TNG detection of the optical afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30385
SUBJECT: GRB 210704A: TNG detection of the optical afterglow candidate
DATE:    21/07/05 23:15:32 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo at gmail.com>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), A. Fiorenzano, C. Padilla (INAF-TNG) on behalf of the CIBO collaboration report:

We observed the field of GRB 210704A (Kunzweiler et al., GCN Circ. 30369; Ursi et al., GCN Circ. 30372; Berretta et al., GCN Circ. 30375; 
Prasad et al., GCN 30378; Malacaria et al. GCN 30380), covering the position of the X-ray afterglow reported by D'Ai et al. (GCN Circ. 30379) 
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 
2021-07-05 from 21:13:11 UT to 21:39:50 UT (i.e. about 1.08 days after the burst).  

The optical afterglow candidate reported by Kim et al. (GCN Circ. 30384) is clearly detected at the following position (J2000): 
RA: 10:36:04.92
Dec: +57:12:59.3
(+/- 0.5"). 


With preliminary photometry we derive the following magnitude:
r = 22.13  +/- 0.13 

(AB; calibrated against the SDSS catalogue). 

As noted by  Kim et al. (GCN Circ. 30384), this source is not visible in archival SDSS and Pan-STARRS images.