Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radio interference reduction in interstellar communications: methods and
  observations   The discovery of interstellar communication signals is complicated by the
presence of radio interference. Consequently, interstellar communication
signals are hypothesized to have properties that favor discovery in high levels
of local planetary radio interference. A hypothesized type of interstellar
signal, delta-t delta-f polarized pulse pairs, has properties that are similar
to infrequent elements of random noise, while dissimilar from many types of
known radio interference. Discovery of delta-t delta-f polarized pulse pairs is
aided by the use of interference-filtered receiver systems that are designed to
indicate anomalous presence of delta-t delta-f polarized pulse pairs, when
pointing a radio telescope to celestial coordinates of a hypothetical
transmitter. Observations reported in previous work (ref. arXiv:2105.03727)
indicate an anomalous celestial pointing direction having coordinates 5.25 +-
0.15 hours Right Ascension and -7.6 +- 1 degrees Declination. Augmented
interference reduction mechanisms used in the current work are described,
together with reports of follow-up radio telescope beam transit measurements
during 40 days. Conclusions and further work are proposed.

7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an