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THE ASTRONOMER Electronic Circular No 3144      2016 Feb 20 16.44UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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SN 2016adj IN NGC 5128
Following the initial announcement on The Astronomer E-Circular 3142, this
object, formerly AT 2016adj, has been re-designated SN 2016adj following
spectral confirmation.

Damian Peach, Hamble-Le-Rice, England reports that he serendipitously
recorded the supernova on 2016 February 7 (16h21mUT) in a pre-discovery
image of NGC 5128 (=Centaurus A). 
Ron Arbour attempted photometry and despite the very close proximity of a
bright star obtained a result of V=14.8.

M. Stritzinger, Aarhus University et. al. reported on The Astronomer's
Telegram 8657 spectroscopic classification based on a visual-wavelength
spectrum obtained on Feb. 9.2 UT with the 2.5-m du Pont Telescope. The
spectrum exhibits prevalent Na-I D absorption at the redshift of NGC 5128
characterised by an equivalent width of 0.44-nm. An additional feature
coincident with the 578.0-nm diffuse interstellar band is measured to have
an equivalent width of 0.06-nm, suggesting an A(V) value between 2 to 4 mag
(Phillips et al. 2013, ApJ, 779, 38).

Given the significant reddening the blue portion of the spectrum has very
low signal-to-noise, however discernible features are present in the red
portion of the spectrum that they attribute to H-alpha, the Ca-II
near-infrared triplet, and Mg-II 922.7-nm. After manually de-reddening the
spectrum assuming E(B-V)=1.0 and Rv=3.1 and then using the spectral
identification tool superfit (Howell et al, 2005, ApJ, 634, 119), we find
the spectrum of AT 2016adj to best resemble the Type-Ib supernova 1999dn
around a week past maximum.

In addition, optical photometry was also computed from multiple images taken
on Feb. 9.2 UT under photometric conditions with the 1-m Swope Telescope.
Computed photometry is as follows:

filter u 18.943 +/- 0.040
filter B 17.395 +/- 0.041
filter g 16.565 +/- 0.038
filter V 15.701 +/- 0.031
filter r 14.613 +/- 0.021
filter i 13.304 +/- 0.017

Guy M Hurst