Recent Discoveries of Infrared Transients and Variables by SPIRITS

ATel #10488; J. E. Jencson, M. M. Kasliwal, S. Adams, D. Cook, S. Tinyanont, S. Kwan, T. Prince (Caltech), R. M. Lau (Caltech/JPL), D. Perley (LJMU), F. Masci, G. Helou, L. Armus, J. Surace, S. D. Van Dyk (Caltech/IPAC), A. Cody (NASA Ames), M. L. Boyer (NASA Goddard), H. E. Bond, A. Monson (PSU), J. Bally (UC Boulder), R. Khan, E. Levesque (U. Washington), O. Fox, R. Williams (STSCI), P. A. Whitelock (SAAO, UCT), S. Mohamed (SAAO), R. D. Gehrz, S. Amodeo, D. Shenoy, R. Carlon, A. Cass, D. Corgan, D. Dykhoff, J. Faella, T. Gburek (U. Minnesota), N. Smith (U. Arizona), M. Cantiello (UCSB), N. Langer (U. Bonn), E. Ofek (WIS), J. Johansson (OKC/WIS), M. Parthasarathy (IIA), E. Hsiao (FSU), M. Phillips, N. Morrell, C. Gonzalez, C. Contreras (LCO), on behalf of the SPIRITS collaboration
on 14 Jun 2017; 00:27 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Jacob Jencson (jj@astro.caltech.edu)

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We report the discoveries of mid-infrared transients/eruptive variables found in the course of the Spitzer InfraRed Intensive Transients Survey (SPIRITS) using Spitzer Early Release Data (ATel #6644, #7929, #8688, #8940, #9434, #10171, #10172). Some of these events may belong to an emerging class of infrared (IR) transients known as eSPecially Red Intermediate Luminosity Transient Events (SPRITEs; Kasliwal et al. 2017, ApJ, 839, 88) defined by peak luminosities between those of novae and supernovae in the range -11 > [4.5] > -14 or 6.3 < log(L/Lsun) < 7.5, [3.6]-[4.5] colors between 0.3 and 1.6 mag, and no detected counterpart at optical wavelengths. Of the events reported here, SPIRITS 17lb is a probable supernova given its high luminosity. In the table below, we list peak observed magnitudes at [3.6] and [4.5], and maximum observed [3.6]-[4.5] colors.

 
Name         | RA (J2000)  | Dec (J2000) | Host Galaxy (DM; Ref.) | UT-discovery | Peak [3.6] (abs) | Peak [4.5] (abs) | Max. [3.6]-[4.5] | Notes 
 
SPIRITS 17lk | 03:46:49.27 | 68:03:52.9  | IC 342 (27.7, c)       | 2017-05-28   | 17.3 (-10.4)     | 16.4 (-11.3)     | 0.9              | b 
SPIRITS 17lg | 03:46:03.55 | 68:08:48.2  | IC 342 (27.7, c)       | 2017-05-28   | 17.6 (-10.1)     | 16.6 (-11.1)     | 1.0              | a 
SPIRITS 17lc | 03:46:07.32 | 68:07:59.0  | IC 342 (27.7, c)       | 2017-05-28   | 17.0 (-10.7)     | 15.8 (-11.9)     | 1.2              | a 
SPIRITS 17lb | 06:16:27.78 | -21:22:51.7 | IC 2163 (32.8, d)      | 2017-05-28   | 15.6 (-17.2)     | 14.5 (-18.3)     | 1.1              | b 
SPIRITS 17kw | 13:25:33.08 | -43:00:51.6 | Centaurus A (27.8, c)  | 2017-05-19   | 16.3 (-11.5)     | 15.6 (-12.2)     | 0.9              | a 
SPIRITS 17kq | 13:25:32.03 | -43:00:41.3 | Centaurus A (27.8, c)  | 2017-05-19   | 16.7 (-11.1)     | 15.8 (-12.0)     | 0.9              | a 
SPIRITS 17kp | 13:25:20.3  | -42:59:20.2 | Centaurus A (27.8, c)  | 2017-05-19   | 17.2 (-10.6)     | 15.8 (-12.0)     | 1.2              | b 
SPIRITS 17kj | 13:36:57.42 | -29:50:19.1 | M83 (28.3, c)          | 2017-05-19   | 17.7 (-10.6)     | 16.6 (-11.7)     | 1.1              | a 
SPIRITS 17kf | 13:25:22.18 | -43:01:17.5 | Centaurus A (27.8, c)  | 2017-05-19   | >16.8 (>11.0)    | 15.5 (-12.3)     | >1.3             | a 
SPIRITS 17kc | 13:25:29.44 | -43:01:40.0 | Centaurus A (27.8, c)  | 2017-05-19   | 16.1 (-11.7)     | 15.4 (-12.4)     | 0.7              | b 
SPIRITS 17ka | 13:37:16.22 | -29:54:18.7 | M83 (28.3, c)          | 2017-05-19   | 18.0 (-10.3)     | 16.3 (-12.0)     | 1.7              | a 
SPIRITS 17fo | 12:18:50.33 | 47:18:11.5  | M106 (29.3, c)         | 2017-03-30   | 17.7 (-11.6)     | 16.6 (-12.7)     | 1.1              | a 
SPIRITS 17fm | 14:03:01.29 | 54:22:54.4  | M101 (29.2, c)         | 2017-03-31   | 17.0 (-12.2)     | 16.8 (-12.4)     | 0.2              | b 
SPIRITS 17fe | 23:57:44.77 | -32:34:58.4 | NGC 7793 (27.8, c)     | 2017-02-16   | 16.5 (-11.3)     | 15.8 (-12.0)     | 0.7              | a 
 

a) Fainter counterpart in reference (2004-2008).

b) No counterpart in reference (2004-2008).

c) Tully et al. 2013, AJ, 146, 86

d) Theureau et al. 2007, A&A, 465, 71

We encourage continued follow-up to discern the nature of these events. Please contact us if additional information (such as finding charts) is needed. We caution that in most cases we do not have spectroscopic confirmation that these transients belong to the reported host galaxies, and there is some chance that a few of them may be unrelated foreground or background events.