Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ASCA Discovery of a Be X-Ray Pulsar in the SMC: AX J0051-733   ASCA observed the central region of the Small Magellanic Cloud, and found a
hard X-ray source, AX J0051-733, at the position of the ROSAT source RX
J0050.8-7316, which has an optical counterpart of a Be star. Coherent X-ray
pulsations of 323.1 +/- 0.3 s were discovered from AX J0051-733. The pulse
profile shows several sub-peaks in the soft (0.7-2.0 keV) X-ray band, but
becomes nearly sinusoidal in the harder (2.0-7.0 keV) X-ray band. The X-ray
spectrum was found to be hard, and is well fitted by a power-law model with a
photon index of 1.0 +/- 0.4. The long-term flux history was examined with the
archival data of Einstein observatory and ROSAT; a flux variability with a
factor > 10 was found.

35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat