Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interstellar reddening correction using He I lines   We present a method to derive the logarithmic extinction coefficient in
optical wavelengths using the emission lines of HeI. Using this procedure we
can avoid selection biases when studying regions with different surface
brightness and we can obtain better measurements of temperature lines, for
example [SIII]6312.

33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
2
The categories of this paper are: math