SPIRITS Discoveries of New Infrared Transients and Variables

ATel #8940; J. E. Jencson, M. M. Kasliwal, S. Tinyanont, Y. Cao, T. Prince (Caltech), R. M. Lau (Caltech/JPL), D. Perley (DARK), F. Masci, G. Helou, L. Armus, J. Surace, S. D. Van Dyk (IPAC), A. Cody (NASA Ames), M. L. Boyer, R. Khan (NASA Goddard), H. E. Bond, A. Monson (PSU), J. Bally (UC Boulder), E. Levesque (U. Washington), 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), O. Fox (UC Berkeley), E. Hsiao (FSU), M. Phillips, N. Morrell, C. Gonzalez, C. Contreras (LCO), on behalf of the SPIRITS collaboration
on 12 Apr 2016; 22:08 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Mansi Manoj Kasliwal (mansi@astro.caltech.edu)

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We report several recently discovered mid-infrared transients/strong variables found in the course of the Spitzer InfraRed Intensive Transients Survey (SPIRITS), using Spitzer Early Release Data (ATel #6644, #7929, #8688). These objects appear to belong to an emerging class of intermediate-luminosity, infrared-dominated transients. They are characterized by peak absolute magnitudes in the range -11 > [3.6] > -16, thus lying in the mid-infrared gap between novae and supernovae. They have extremely red colors, [3.6] - [4.5] > 0.5, and no detected optical counterparts.

 
Name         | RA (J2000)  | Dec (J2000) | Host Galaxy (DM; Ref.) | UT-discovery | Peak [3.6] (abs) | Peak [4.5] (abs) | Max. [3.6]-[4.5] | iPTF Optical Limits | Notes 
 
SPIRITS 16ix | 12:29:03.16 | +13:11:30.7 | NGC 4461 (31.5, c)     | 2016-3-30    | 17.3 (-14.2)     | 15.7 (-15.8)     | 1.6              | g > 20.7; 2016-4-6  | b 
SPIRITS 16fz | 12:56:39.10 | +21:41:43.2 | M 64 (28.6, c)         | 2016-3-24    | 16.9 (-11.7)     | 16.1 (-12.5)     | 0.9              | g > 20.8; 2016-4-6  | a 
SPIRITS 16ea | 12:15:38.61 | +36:19:46.9 | NGC 4214 (27.3, c)     | 2016-3-18    | 17.5 (-9.8)      | 16.3 (-11.0)     | 1.4              | ...                 | a 
SPIRITS 16az | 12:30:27.78 | +41:39:41.3 | NGC 4490 (29.9, d)     | 2016-3-5     | 16.7 (-13.2)     | 16.2 (-13.7)     | 0.5              | g > 21.1; 2016-4-6  | a 
SPIRITS 16aj | 09:32:11.64 | +21:30:03.0 | NGC 2903 (29.9, c)     | 2016-2-7     | 16.5 (-13.4)     | 15.9 (-14.0)     | 0.7              | g > 20.1; 2016-4-6  | b 

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

b) No counterpart in reference (2007 - 2010).

c) Tully et al. 2013

d) Pastorello et al. 2008

We encourage follow-up to discern the nature of these events. Please contact us if additional information (such as finding charts) is needed. We caution that 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.