Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The first simultaneous X-ray/gamma-ray observations of Cyg X-1 by Ginga
  and OSSE   We present the results of 4 simultaneous observations of Cygnus X-1 by Ginga
and OSSE. The X-ray/gamma-ray spectra can be described by an intrinsic
continuum and a component due to Compton reflection including an iron K-alpha
line. The intrinsic spectrum at X-ray energies is a power-law with a photon
spectral index of Gamma=1.6. The intrinsic gamma-ray spectrum can be
phenomenologically described by either a power-law without cutoff up to 150
keV, and an exponential cutoff above that energy, or by an exponentially cutoff
power law and a second hard component.

31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc