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Astron. Astrophys. 338, L59-L62 (1998)


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Letter to the Editor

A BeppoSAX observation of XTE J0055-724 = 1SAX J0054.9-7226, a new X-ray pulsar in the SMC

A. Santangelo 1, G. Cusumano 1, D. Dal Fiume 2, G.L. Israel * 3, L. Stella 3, M. Orlandini 2 and A.N. Parmar 4

1 Istituto di Fisica Cosmica ed Applicazioni all'Informatica C.N.R.,Via U. La Malfa 153, I-90146 Palermo, Italy
2 Istituto di Tecnologie E Studio delle Radiazioni Extraterrestri CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
3 Osservatorio Astronomico di Roma, via Frascati 33, I-00040, Monteporzio Catone (Roma), Italy
4 Astrophysics Division, Space Science Department of ESA, ESTEC, P.O. Box 299, 2200 AG Noordwijk, The Netherlands

Received 19 June 1998 / Accepted 3 August 1998

Abstract

We report on the result of a BeppoSAX Target of Opportunity Observation of the hard pulsating X-ray source XTE J0055-724 = 1SAX J0054.9-7226, in the Small Magellanic Cloud (SMC). The source was detected by BeppoSAX at a flux level of [FORMULA] erg cm-2 s-1 (2-10 keV) and its position is consistent with that of the ROSAT PSPC source 1WGA J0054.9-7226 and the Einstein source 2E 0053.2-7242. Both these sources were known to possess a marked variability, on timescales ranging from months to years. The BeppoSAX energy spectrum of 1SAX J0054.0-7226 is hard and well modelled by an absorbed hard power-law model with a photon index [FORMULA]. BeppoSAX detected up to 40 keV the [FORMULA] s pulsations originally discovered with by R XTE (Marshall & Lochner 1998a; Santangelo et al. 1998).

Key words: X-rays: binaries – individual (1SAX J0054.9 – 7226) – X-rays: pulsars – galaxies: Magellanic Clouds

* Affiliated to I.C.R.A.

Send offprint requests to: A. Santangelo: andrea@ifcai.pa.cnr.it

© European Southern Observatory (ESO) 1998

Online publication: September 14, 1998

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