Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SPIRITS 15c and SPIRITS 14buu: Two Obscured Supernovae in the Nearby
  Star-Forming Galaxy IC 2163   SPIRITS---SPitzer InfraRed Intensive Transients Survey---is an ongoing survey
of nearby galaxies searching for infrared (IR) transients with Spitzer/IRAC. We
present the discovery and follow-up observations of one of our most luminous
($M_{[4.5]} = -17.1\pm0.4$ mag, Vega) and red ($[3.6] - [4.5] = 3.0 \pm 0.2$
mag) transients, SPIRITS 15c. The transient was detected in a dusty spiral arm
of IC 2163 ($D\approx35.5$ Mpc). Pre-discovery ground-based imaging revealed an
associated, shorter-duration transient in the optical and near-IR (NIR). NIR
spectroscopy showed a broad ($\approx 8400$ km s$^{-1}$), double-peaked
emission line of He I at $1.083 \mu$m, indicating an explosive origin. The NIR
spectrum of SPIRITS 15c is similar to that of the Type IIb SN 2011dh at a phase
of $\approx 200$ days. Assuming $A_V = 2.2$ mag of extinction in SPIRITS 15c
provides a good match between their optical light curves. The IR light curves
and the extreme $[3.6]-[4.5]$ color cannot be explained using only a standard
extinction law. Another luminous ($M_{4.5} = -16.1\pm0.4$ mag) event, SPIRITS
14buu, was serendipitously discovered in the same galaxy. The source displays
an optical plateau lasting $\gtrsim 80$ days, and we suggest a scenario similar
to the low-luminosity Type IIP SN 2005cs obscured by $A_V \approx 1.5$ mag.
Other classes of IR-luminous transients can likely be ruled out in both cases.
If both events are indeed SNe, this may suggest $\gtrsim 18\%$ of nearby
core-collapse SNe are missed by currently operating optical surveys.

25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph