<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Voss, R.</style></author><author><style face="normal" font="default" size="100%">Pietsch, W.</style></author><author><style face="normal" font="default" size="100%">Haberl, F.</style></author><author><style face="normal" font="default" size="100%">Stiele, H.</style></author><author><style face="normal" font="default" size="100%">Greiner, J.</style></author><author><style face="normal" font="default" size="100%">Sala, G.</style></author><author><style face="normal" font="default" size="100%">Hartmann, D. H.</style></author><author><style face="normal" font="default" size="100%">Hatzidimitriou, D.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Three X-ray transients in M ;31 observed with Swift</style></title><short-title><style face="normal" font="default" size="100%">Astronomy and Astrophysics</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">31</style></keyword><keyword><style  face="normal" font="default" size="100%">Astrophysics</style></keyword><keyword><style  face="normal" font="default" size="100%">galaxies: individual: M</style></keyword><keyword><style  face="normal" font="default" size="100%">X-rays: binaries</style></keyword><keyword><style  face="normal" font="default" size="100%">X-rays: galaxies</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2008/10/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2008A&amp;A...489..707V</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">489</style></volume><pages><style face="normal" font="default" size="100%">707 - 711</style></pages><isbn><style face="normal" font="default" size="100%">0004-6361</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Aims: The purpose of this study is to find transient X-ray sources in M 31 and to investigate and classify their nature. &lt;BR /&gt;Methods: Three X-ray transients were observed with Swift. For each of the three X-ray transients, we used the Swift X-ray and optical data with observations from XMM-Newton and Chandra to investigate the lightcurves and the spectra of the outburst, thereby identifying the source types. &lt;BR /&gt;Results: The outburst of XMMU J004215.8+411924 lasted about one month. The source had a hard power-law spectrum with a photon index of 1.6. It was previously identified as a Be/X-ray binary based on the optical identification with a star. However, we show that, with improved source coordinates it is clear that the optical source is not the counterpart to the X-ray source. The source SWIFT J004217.3+411532 had a bright outburst, after which it slowly decayed over half a year. The spectrum was soft, corresponding to a thermal accretion disc with an innermost temperature of ~250-600 eV. The source was not seen in the optical, and the soft spectrum indicates that the source is most likely a black-hole low-mass X-ray binary. M31N 2006-11a is a nova that was previously observed in the optical. We detected it both in X-rays and UV with Swift ~half a year after the optical maximum, after which it decayed below the Swift detection threshold within a month. The spectrum of the X-ray transient can be modelled by a black-body with a temperature of 50 eV. We use catalogues of X-ray transients in M 31 to estimate their rate, and we find a lower limit of 9 yr&lt;SUP&gt;-1&lt;/SUP&gt;.</style></abstract></record></records></xml>