Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxies or Asteroids? -- 12 micron Sources in 9 QSO Fields Near the
  Ecliptic   We consider 9 fields of low ecliptic latitude observed at 12 microns centered
on QSOs. In these fields we detect 7 additional background sources at the level
of 0.4-4mJy in 70 square arcminutes. 4 of these sources correspond to galaxies
seen in the Digitized Sky Survey. 3 of these sources are not observed in this
survey. The 4 sources with optical counterparts are low redshift objects with
low infrared to optical flux ratios and so low inferred infrared luminosities
L_FIR <~ 10^9 L_solar. Statistical arguments suggest that the unidentified
sources are more likely to be distant L_FIR > 10^10 L_solar starbursting
galaxies, rather than asteroids or late-type stars.
  2 of our QSO fields are likely to have starbursting galaxies at moderately
high redshift near the QSO (in angular scale). Since the lensing optical depth
towards these QSOs is expected to peak at moderate redshift there is some
possibility that these galaxies are in clusters that lense the QSOs. If none of
our sources are asteroids then the number of small (km) sized main belt
asteroids cannot be larger than 500,000 per absolute magnitude bin.

30
The categories of this paper are: q-alg
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess