Swift/UVOT Observations show SN2016ccj to be UV-blue for a SN Ia
ATel #9035; Peter J. Brown (Mitchell Institute/Texas A&M) & P. Milne (U. Arizona)
on 10 May 2016; 02:42 UT
Credential Certification: Peter J. Brown (grbpeter@yahoo.com)
Subjects: Optical, Ultra-Violet, Supernovae
Following the classification of SN2016ccj (ASASSN-16ex; Kiyota et al. 2016 ATEL#9020) as a Type Ia supernova similar to super-Chandrasekhar mass SNe 2006gz and 2009dc (Piascik & Steele 2016 ATEL#9023; Tomasella et al. 2016 ATEL#9024), we requested observations with Swift's Ultraviolet/Optical Telescope (UVOT; Gehrels et al. 2004, Roming et al. 2005). Observations began 2016-05-05 22:49:27 UT. The following UVOT magnitudes were measured: v = 17.1 +/- 0.1 (157 s exposure time), b = 17.3 +/- 0.1 (157 s), u = 16.3 +/- 0.1 (157 s), uvw1 = 17.2 +/- 0.1 (315 s), uvm2 = 17.8 +/- 0.1 (1480 s), and uvw2 = 18.1 +/- 0.1 (629 s). These magnitudes are reduced using the method outlined for the Swift Optical Ultraviolet Supernova Archive (SOUSA; Brown et al 2014, Ap&SS, 354, 89, arXiv:1407.3808) on the Swift/UVOT Vega-based photometric system (Poole et al. 2008, Breeveld et al. 2011). Galaxy light has not been subtracted, but the supernova is much brighter than the underlying galaxy light.
Assuming a redshift of z=0.03 (distance modulus of 35.9), the UV colors and absolute magnitudes of SN2016ccj are blue and bright similar to those of other super-Chandrasekhar mass candidates observed with UVOT (Brown et al. 2014). Ultraviolet spectroscopy observations with the Hubble Space Telescope have been triggered through the program "An Ultraviolet View of Overluminous Type Ia Supernovae". The first observation is planned for May 14, 2016 02:00:02-04:34:36 UT, near the expected time of maximum light in the optical.
