Astron. Astrophys. 325, L17-L20 (1997)

2. Observations and Data Reduction

3C273 was observed during the Science Verification Phase (SVP) from 1996 July 18 to July 21 with the NFI of the BeppoSAX  satellite. The NFI consist of four co-aligned detectors: the Low Energy Concentrator Spectrometer (LECS: 0.1-10 keV; Parmar et al. 1997), the Medium Energy Concentrator Spectrometer (MECS: 1-10 keV) (Boella et al. 1997), the High Pressure Gas Scintillation Proportional Counter (HPGSPC: 4-120 keV; Manzo et al. 1997) and the Phoswich Detector System (PDS: 15-300 keV; Frontera et al. 1997).

All instruments operated in default configuration and data were telemetred in direct modes. Standard data selection criteria were applied ¹. LECS, MECS and PDS data were reduced using SAXDAS V.1.1.0 package. For HPGSPC data, XAS V.2.0.1 package (Chiappetti 1996) was used. Data analysis was performed using the XANADU package. Total usable exposure time was 12 ksec, 131 ksec, 32 ksec and 64 ksec for LECS, MECS, HPGSPC and PDS, respectively. The short LECS exposure is due to the LECS being operated only during spacecraft night. In the LECS image the source was about 2' away from the center of the field of view and was partially obscured by a coarse strongback structure.

The LECS and the three MECS spectra were accumulated on circular regions of 8' and 4' radius, respectively. Background spectra were extracted from blank fields observations in the same position of the source. HPGSPC and PDS net source spectra and light curves were produced by subtracting the off- from the on-source products. A discussion of the systematics associated with such a procedure can be found in Manzo et al. (1997) and Matt et al. (1997) respectively.

The spectra of all the instruments were rebinned to achieve at least 20 counts per bin, in order to ensure the applicability of test in the spectral fits. Publicly available matrices (1996, December 31 release) were used for all the instruments but the LECS, for which an ad hoc effective area was used to account for the offset of the source centroid.

© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998

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