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[vsnet-grb 63] GRB 010214, candidate optical afterglow

GRB 010214, candidate optical afterglow

    The following message is from GCN No. 955:

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  955
SUBJECT: GRB010214, candidate optical afterglow
DATE:    01/02/21 17:41:23 GMT
FROM:    Evert Rol at U.Amsterdam  <evert@astro.uva.nl>

E. Rol, I. Salamanca, L. Kaper, P. Vreeswijk (University of
Amsterdam), P. Lacerda (Leiden Observatory), S. Hodgkin, P.
Tzanavaris (University of Cambridge), N. Tanvir (University of
Hertfordshire), report on behalf of a larger collaboration:

"We have observed the BeppoSAX error box of GRB010214 (Gandolfi, GCN
#932) with the 4.2m William Herschel Telescope (+ Prime Focus) and
with the 2.2m Isaac Newton Telescope (+ WFC) at La Palma, as follows:


  Telescope     Date          Filter  Exp.time  Seeing   Lim. mag.
		(UT)		       (secs)    (")     (3 sigma)  
  =================================================================
  WHT (+PF)   2001 Feb 15.26    R      2 x 225   0.84     ~23.5
  INT (+WFC)  2001 Feb 17.25    R      2 x 900   1.2	  ~24.2

(Note that in our calibration, the USNO star mentioned by Masetti et
al. (GCN #945) has a magnitude of R=18.4 instead of R=18.3.)

Within the refined NFI error box (Frontera et al., GCN #950), we
detect one object which faded from R = 22.9 to R = 24.1 (1 sigma error
about 0.2 mag) between the two observations. 
The source seems to be extended, likely to be due to an underlying
galaxy. We consider this object to be a strong candidate for the optical
afterglow of GRB010214. The candidate is located at RA = 17:41:02.9
and Dec = 48:34:30 (J2000; error about 1 arcsec).

Another variable source is located just outside the refined NFI error
box, though within the initial NFI error box (Gandolfi, GCN #937),
with a position of RA = 17:41:04.6, Dec = 48:33:47 (J2000). This
source has faded from R = 23.1 to 24.0 (error of ~0.2 mag).  The
infrared object mentioned by Di Paola et al. (GCN #939; see also
Antonelli, GCN #944) is clearly visible in our images (R~22.6 in the
WHT image). We measure two slightly different magnitudes (difference
of about 0.3), which might indicate a variable star.

Images and more information can be found on
http://www.astro.uva.nl/~evert/grb010214/

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