Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A 2.09-h Photometric Periodicity in GW Librae   We have found a 2.09 h modulation in brightness of the dwarf nova GW Lib.
This bears no special relationship to the 1.28 h spectroscopic period that is
believed to be the orbital period. It was present in May 2001, but not in
observations made in 1997 and 1998 and is of unknown origin. Similar
unexplained periodicities are present in FS Aur and V2051 Oph.

31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
2
The categories of this paper are: math