TITLE: GCN CIRCULAR NUMBER: 16813 SUBJECT: GRB 140903A: Chandra detection of the afterglow DATE: 14/09/10 21:26:39 GMT FROM: Takanori Sakamoto at AGU T. Sakamoto (AGU), E. Troja (GSFC/UMCP), N. Gehrels (GSFC), J. Norris (BSU), S. D. Barthelmy (GSFC), J. L. Racusin (GSFC), N. Kawai (Tokyo Tech), A. Fruchter (STScI) A Chandra ToO observation of a short GRB 140903A (Cummings et al., GCN Circ. 16763; Cummings et al., GCN Circ. 16765) started on September 6 08:54 UT (~2.7 days after the GRB trigger) for a total of 19.8 ksec. The X-ray afterglow was clearly detected at a position (RA, Dec) = (238.013519, +27.60303) which is equivalent to: RA (J2000) = 15 52 03.24 Dec (J2000) = +27 36 10.9 The 1-sigma statistical error is 0.05 and 0.04 arcsec on RA and Dec respectively. The systematic error of the Chandra aspect solution is 0.3 arcsec (radius, 68% containment; i.e, http://cxc.harvard.edu/cal/ASPECT/celmon/) which dominates the localization uncertainty. The Chandra location is consistent with the enhanced XRT position (De Pasquale et al., GCN Circ. 16767) and the reported NIR, optical and radio afterglow/host candidate (Capone et al., GCN Circ. 16769; Cenko et al., GCN Circ. 16785; Cenko et al., GCN Circ. 16770; Fruchter et al., GCN Circ. 16776; Fong, GCN Circ. 16777; Dichiara et al., GCN Circ. 16781; Xu et al. GCN Circ. 16783; Levan et al. GCN Circ. 16784). Our Chandra detection confirms the association of the reported NIR, optical and radio candidate to GRB 140903A. Further Chandra observations are planned. We would like to thank the Chandra operation team for rapidly approving and making this observation.