Kühnel, M.Müller, S.Kreykenbohm, I.Fürst, F.Pottschmidt, KatjaRothschild, R. E.Caballero, I.Grinberg, V.Schönherr, G.Shrader, C.Klochkov, D.Staubert, R.Ferrigno, C.Torrejón, J.-M.Martínez-Núñez, S.Wilms, J.2023-09-072023-09-072013-07-08Kühnel, M., S. Müller, I. Kreykenbohm, F. Fürst, K. Pottschmidt, R. E. Rothschild, I. Caballero, et al. “GRO J1008−57: An (Almost) Predictable Transient X-Ray Binary.” Astronomy & Astrophysics 555 (July 1, 2013): A95. https://doi.org/10.1051/0004-6361/201321203.https://doi.org/10.1051/0004-6361/201321203http://hdl.handle.net/11603/29614A study of archival RXTE, Swift, and Suzaku pointed observations of the transient high-mass X-ray binary GRO J1008−57 is presented. A new orbital ephemeris based on pulse arrival-timing shows the times of maximum luminosities during outbursts of GRO J1008−57 to be close to periastron at orbital phase − 0.03. This makes the source one of a few for which outburst dates can be predicted with very high precision. Spectra of the source in 2005, 2007, and 2011 can be well described by a simple power law with high-energy cutoff and an additional black body at lower energies. The photon index of the power law and the black-body flux only depend on the 15–50 keV source flux. No apparent hysteresis effects are seen. These correlations allow us to predict the evolution of the pulsar’s X-ray spectral shape over all outbursts as a function of just one parameter, the source’s flux. If modified by an additional soft component, this prediction even holds during GRO J1008−57’s 2012 type II outburst.15 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/Text