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THE ASTRONOMER Electronic Circular No 3161      2016 Apr 15 20.54UT
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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T CORONAE BOREALIS
On AAVSO Special Notice #415 Elizabeth Waagen reports the symbiotic
recurrent nova T CrB has entered a super-active state, and it is brighter
and bluer than it has been since before its last outburst in 1946.
Multicolor and visual ongoing observations are requested.

Visual and multicolor observations in the AAVSO International Database show
that the average magnitude of T CrB was V ~ 10.2-10.3 until early February
2015. Its average magnitude then brightened to V ~ 10.0 and remained there
until early February 2016, when it began brightening again and has currently
reached V ~ 9.2. The B-V is roughly half what it was two years ago. A light
curve of T CrB showing its recent behaviour is included on the webpage:
https://www.aavso.org/aavso-special-notice-415) 

T CrB has been observed twice in outburst, in 1866 and 1946. 
Each time it brightened rapidly to V ~2.0, then declined back to
pre-outburst levels.

A recent paper by U. Munari, S. Dallaporta, and G. Cherini
(http://arxiv.org/pdf/1602.07470.pdf) gives an analysis of the current
behaviour and that of 1947-2016. Their abstract
begins: "The recurrent nova T CrB has entered in 2015 a phase of
unprecedented high activity. To trace something equivalent, it is necessary
to go back to 1938, before the last nova eruption in 1946. The 2015
super-active state is characterized by: a large increase in the mean
brightness (Delta B =0.72 mag over the underlying secular trend), vanishing
of the orbital modulation from the B-band light curve, and appearance of
strong and high ionization emission lines, on top of a nebular continuum
that overwhelms at optical wavelengths the absorption spectrum of the M
giant..." 

For now, nightly observations are requested, in V and B if possible. Other
bands and visual observations are also strongly encouraged. 

Coordinates: R.A. 15 59 30.16  Dec. +25 55 12.6  (2000.0)

Editor:
Finder charts with a comparison star sequence are on the BAAVSS site. Please
send results to Gary Poyner for TA at the end of each month and also input
to the BAAVSS database.

Guy M Hurst