Kühnel, MatthiasFalkner, SebastianGrossberger, ChristophBallhausen, RalfDauser, ThomasSchwarm, Fritz-WalterKreykenbohm, IngoNowak, Michael A.Pottschmidt, KatjaFerrigno, CarloRothschild, Richard E.Martínez-Núñez, SilviaTorrejón, José MiguelFürst, FelixKlochkov, DmitryStaubert, RüdigerKretschmar, PeterWilms, Jörn2023-09-012023-09-012016-02-29Kühnel, Matthias, Sebastian Falkner, Christoph Grossberger, Ralf Ballhausen, Thomas Dauser, Fritz-Walter Schwarm, Ingo Kreykenbohm, Michael A. Nowak, Katja Pottschmidt, Carlo Ferrigno, Richard E. Rothschild, Silvia Martínez-Núñez, José Miguel Torrejón, Felix Fürst, Dmitry Klochkov, Rüdiger Staubert, Peter Kretschmar, and Jörn Wilms. 2016. “THE GOODNESS OF SIMULTANEOUS FITS IN ISIS”. Acta Polytechnica 56 (1):41-46. https://doi.org/10.14311/APP.2016.56.0041.https://doi.org/10.14311/APP.2016.56.0041http://hdl.handle.net/11603/29526In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to check the goodness of these fits: we investigate the goodness of each fit in all datasets, we define a combined goodness exploiting the logical structure of a simultaneous fit, and we stack the fit residuals of all datasets to detect weak features. These tools are applied to all RXTE-spectra from GRO 1008−57, revealing calibration features that are not detected significantly in any single spectrum. Stacking the residuals from the best-fit model for the Vela X-1 and XTE J1859+083 data evidences fluorescent emission lines that would have gone undetected otherwise.6 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