Faculty of Science (FNWI) - Anton Pannekoek Institute for Astronomy (API)
Abstract
Following the discovery of the new hard X-ray transient IGR J17511-3057 by INTEGRAL (Atel #2196) and its classification as a millisecond pulsar by RXTE (Atel #2197), a Swift ToO was performed. Swift/XRT observed IGR J17511-3057 on 2009-09-13 at 19:53:31 for a total exposure time of 4 ks. The first 2.5 ks were accumulated in window timing (WT) mode. A thermonuclear type-I X-ray burst was discovered in the WT light curve of the source at 2009-09-14 00:51:37 UTC with an exponential decay time of ~12.5 s.