Astron. Astrophys. 319, 515-524 (1997)

2. The data base

In this work, we used pulse frequency records compiled from the published literature (Nagase 1989; Gilfanov et al. 1991) and generated from BATSE observations. The total time span of the observations covers approximately yr. The measured angular velocities are plotted as a function of time in Fig. 1. The BATSE detections of angular velocities are plotted in Fig. 2 . These records are measured on the basis of daily analysis after removing binary motion of the neutron star and are available through anonymous ftp from HEASARC. The BATSE data base contains 1219 pulse frequency and pulse flux measurements of OAO 1657-415 in a time span of over 3 years. (BATSE instrument has 8 uncollimated detector modules arranged on the corners of the CGRO spacecraft which are sensitive keV; for details of the observatory and observation see Fishman et al., 1989; Chakrabarty et al., 1993). The gaps in Fig. 2 corresponds to either no detection of the source or unsignificant detections.

Fig. 1. Angular velocity time series history of OAO 1657-415.

Fig. 2. Angular velocity records of BATSE observations (same as Fig. 1).

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998
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