2. Observations and data analysis
In our analysis we used all the publicly available data obtained from RXTE archive including 24 pointed observations. The 24 observations quasi evenly cover the 1998 outburst of the source with a total exposure of ks. The list of observations is presented in Table 1.
For data reduction we used the standard FTOOLS package version 5.0 For the spectral analysis we used PCA data collected in the 3-20 keV energy range. The response matrix was constructed for every observation using pcarmf v3.5. For the PCA background subtraction we applied a Very Large Events (VLE)-based model. The standard dead time correction procedure was applied to the PCA data. In order to account for the uncertainties of the response matrix, a 1 systematic error was added to the statistical error for each PCA energy channel.
HEXTE data reduction was done with FTOOLS 5.0 standard tasks and according to RXTE GOF recommendations.
We generated an averaged energy spectrum of XTE J2012+381 for each of the 24 observations. The spectral data were approximated with the simplest two-component model: the sum of the XSPEC "multicolor disk black body" (Mitsuda et al. 1984) and a simple power law model with inclusion of a broad gaussian emission line at 6.4 keV. The results of the spectral approximation of the PCA data with analytical models described above are presented in Table 2.
Table 2. Spectral parameters of XTE J2012+381, derived using a combination of a multicolor disc blackbody, power law and gaussian emission line. Parameter errors correspond to a confidence level for the assumed systematic uncertainty of data.
For the timing analysis of XTE J2012+381 the PCA Generic Event timing mode data were used. We generated power density spectra (PDS) in the 0.001-4096 Hz frequency range using combined data of several consecutive observations in order to improve the statistical significance of the results. The resulting spectra were logarithmically rebinned to reduce scatter at high frequencies and normalized to the square root of fractional variability rms. The white noise due to the Poissonian statistics corrected for the dead-time effects, was subtracted (Vikhlinin, Churazov & Gilfanov 1994; Zhang et al. 1995; Revnivtsev, Gifanov & Churazov 2000).
© European Southern Observatory (ESO) 2000
Online publication: October 30, 2000