[vsnet-grb-info 27445] GRB 210222B: GOTO confirmation of afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29548
SUBJECT: GRB 210222B: GOTO confirmation of afterglow detection
DATE:    21/02/23 00:25:43 GMT
FROM:    Travis Mong at Monash University  <yik.mong at monash.edu>

Y-L Mong (1); K. Wiersema (2); K. Tse (1); K. Ackley (1); D. K. Galloway
(1); M. Dyer (3); J. Lyman (2); K. Ulaczyk (2); D. Steeghs (2); V. Dhillon
(3); P. O'Brien (4); G. Ramsay (5); S. Poshyachinda (6); R. Kotak (7); L.
Nuttall (8); D. Pollacco (2); R. Breton (9)

((1) Monash University, (2) Warwick University, (3) University of
Sheffield, (4) University of Leicester, (5) Armagh Observatory &
Planetarium, (6) National Astronomical Research Institute of Thailand, (7)
University of Turku, (8) University of Portsmouth, (9) University of
Manchester) report on behalf of the GOTO collaboration:

We carried out observations with the Gravitational-wave Optical

Transient Observer (GOTO) on La Palma in response to GRB 210222B

(Gropp et al; GCN 29545).

We made a series of 4x90 s exposures using our wide L-band filter

(400-700 nm) covering the Swift XRT error box, beginning around 54 s after
the trigger, with midtime of the first observation 22:42:05.21 UT on 22
February 2021.

We detect an uncatalogued source located at (J2000):

RA 10:18:25.42

Dec +53:24:55.89

confirming the OT reported by MASTER (Lupinov et al.; GCN 29544),

BOOTES-1 (Malesani et al.; GCN 29546) and LCO (Strausbaugh et al.; GCN
29547). We find an equivalent magnitude of g = (16.58 +/- 0.03) mag based
on calibration against PanSTARRS DR1 photometry in ATLAS_REFCAT2 (Tonry et
al. 2018).

Observations are continuing.

GOTO is operated at the La Palma observing facilities of the University

of Warwick on behalf of a consortium including the University of

Warwick, Monash University, Armagh Observatory, the University of

Leicester, the University of Sheffield, the National Astronomical

Research Institute of Thailand (NARIT), Turku University, Portsmouth
University,

Manchester University and the Instituto de Astrofisica

de Canarias (IAC) (https://goto-observatory.org)