Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An improvement of the BeppoSAX LECS and MECS positioning accuracy   We present a study of the source positioning accuracy of the LECS and MECS
instruments on-board BeppoSAX. From the analysis of a sample of archival images
we find that a systematic error, which depends on the spacecraft roll angle and
has an amplitude of ~17'' for the LECS and ~27'' for the MECS, affects the sky
coordinates derived from both instruments. The error is due to a residual
misalignment of the two instruments with respect to the spacecraft Z axis
arisen from the presence of attitude inaccuracies in the observations used to
calibrate the pointing direction of LECS and MECS optical axes. Analytical
formulae to correct LECS and MECS sky coordinates are derived. After the
coordinate correction the 90% confidence level error radii are 16'' and 17''
for LECS and MECS respectively, improving by a factor of ~2 the source location
accuracy of the two instruments. The positioning accuracy improvement presented
here can significantly enhance the follow-up studies at other wavelengths of
the X-ray sources observed with LECS and MECS instruments.

15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex