XRF 020903, no optical afterglow

A blow-up of the MOA image obtained 4.18 hr after the XRF 020903 including the position of the possible supernova reported by Soderberg et al. (GCN#1354) 4.18 hr after the XRF 020903. The red circle marks the position of the possible SN north of the z = 0.23 elliptical galaxy. North is up and East to the left.

GCN CIRCULAR 1563

XRF 020903, no optical afterglow
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A. J. Castro-Tirado (IAA-CSIC,Granada)
P. Tristram (Univ. of Auckland)
J. Gorosabel (IAA-CSIC, Granada)
J. M. Castro Cerón (ROA, San Fernando)
P. Kilmartin (Mt. John Univ. Observatory)
Y. Furuta (Univ. of Nagoya)
Ph. Yock (Univ. of Auckland)

communicate:
"Following the report of a possible SN associated to the X-ray flash 020903 (GCN#1530) by Soderberg et al. (GCN#1554), we have re-examined the images obtained with the 0.6-m (+MOA camera) at Mt. John Observatory in a wide B- and R-band filters (600-s and 1200-s respectively, GCN#1531) starting on Sep 3.5944 UT (i.e. 4.18 hr after the event). If we extra- polate back the power-law decay expected from an optical afterglow with index 0.6 (as given in the Soderberg et al. web page), we should have detected a R = 16.7 object at the position of the proposed candidate. However, the R-band image reveals nothing as bright as 16-17th mag at the candidate position, north to the z = 0.23 elliptical galaxy. The MOA image can be seen at www.iaa.es/~ajct/XRFs/xrf020903 . Therefore, unless the optical afterglow would be similar to that of the unique GRB 970508, we would tend to support the identification of the variable object with a radioloud AGN, as proposed by Gal-Yam (GCN#1556)."