Astroblog

April 15, 2011

Further to AAVSO Alert Notice 436
(http://www.aavso.org/aavso-alert-notice-436), a fast photometry
observing campaign has been initiated by Dr. Bradley Schaefer
(Louisiana State University) to monitor the recurrent nova T Pyxidis
throughout its current eruption. (see also GRAS NEWS- 
Caught in the Act! Nova T_Pyxidis in Outburst) 
Brief summary of eruption: The recurrent nova T Pyx was discovered in
outburst by M. Linnolt (Hawaii, United States) at visual magnitude
13.0 on 2011 April 14.2931 (JD 2455665.7931), and confirmed by
A. Plummer (Linden, NSW, Australia) at visual magnitude 12.2 on April
14.3847 (JD 2455665.8847) and S. Kerr (Glenlee, QLD, Australia) at
visual magnitude 11.3 on April 14.4410 (JD 2455665.9410).  This is
the first outburst of T Pyx since December 7, 1966, nearly 45 years
ago. As of April 15.6271 (JD 2455667.12708), it had brightened to
visual magnitude 8.3 (A. Pearce, Nedlands, WA, Australia). If it
behaves as in past eruptions, it can be expected to brighten to
magnitude 6. All observations -- visual, CCD, and PEP observations,
and CCD time series -- are encouraged.

Campaign: Full details of the campaign may be found on the T Pyx
campaign information page (http://www.aavso.org/campaign-monitor-
recurrent-nova-t-pyx-throughout-2011-eruption). The following is
a description of the campaign summarized from that page:

"The goal is be to get nearly-fulltime coverage of T Pyx with time
resolution of minutes throughout the entire eruption up until T Pyx
is lost behind the Sun around the start of August. This will require
many observers, widely spaced around the world, each taking long runs
of CCD images.  The eruption takes roughly 9 months to go back to
quiescence, but we will only go from now until the end of July (3.5
months) when T Pyx is lost behind the Sun.

"...V filter is preferred for CCD observations, with second choice
being B filter, third choice R, and last choice unfiltered.  (T Pyx
should be magnitude 6-10 over this whole time interval, so a filter
will help against saturation.)  To make for a uniform magnitude scale
by everyone, please use the following comparison stars:

COMPARISON: AAVSO="93"  HD77862    09:04:09.4 -32:11:16 B=9.85,V=9.31
COMP2:      AAVSO="69"  HD77645    09:02:51.8 -32:26:24 B=6.90,V=6.93
COMP3:      AAVSO="115" CD-31o6884 09:04:43.8 -32:24:47 B=12.12,V=11.52
Variable star (do not use):
          AAVSO="84"   HD77938    09:04:29.5 -32:26:54 B=9.49, V=8.44


Please use the COMPARISON star (AAVSO="93") for all the differential
photometry as it will have nearly the same colors as T Pyx.  Use the
other backup comparison stars only if you have troubles with field size,
saturation, or SNR problems. With the bright stars and differential
photometry, T Pyx can be followed down low on the horizon.

"T Pyx is only one of ten known recurrent novae in our own Milky Way
galaxy.  It has erupted in 1890, 1902, 1920, 1944, and 1967...we...are
not missing any eruptions in this time interval...Judging from the 1967
eruption light curve, the current eruption light curve will stall out
of its rise at around V=8 around 15 April,  slowly rise to a peak near
V=6.4 around 20 May, slowly fade to V=10 by middle August, then have a
sudden drop by two magnitudes over the next 20 days (with drop being
invisible due to the Sun)...


"Recurrent novae...are one of the best candidate systems for being the
progenitor of Type Ia supernova.  This progenitor problem is a long
standing sore mystery...Indeed, in last year's Decadal Survey, the
National Academy of Sciences identified the progenitor problem one of
the four most important problems in all astronomy...T Pyx...[is] the
lynchpin of many arguments and discussions for the progenitor problem.
The work on this eruption will largely be aimed at testing whether
T Pyx will become a Type Ia supernova.

"...Only one nova has large amounts of fast photometry...the recurrent
nova U Sco, which erupted in 2010.  For this, I organized a large
worldwide collaboration of (mostly amateur) observers, and we measured
37,000 magnitudes..With this awesome data set, we discovered two
completely new phenomena...who knows what more will be discovered for
the second very-well-observed nova.


"I envision a repeat of the wildly successful U Sco worldwide
collaboration of astronomers, so that we can get very detailed light
curves of T Pyx and all its expected-complicated variations throughout
the eruption. The goal is to follow all the big and subtle variations
in exquisite detail so that we can understand their causes...All
contributing observers will be included as authors of the resulting
papers..."

Coordinates: RA 09 04 41.5 , Dec -32 22 47.4 (J2000.0)

Charts for T Pyx may be plotted using the AAVSO's Variable Star Plotter:
http://www.aavso.org/vsp


Please use the current chart which has the most up-to-date comparison
star magnitudes.


Please promptly submit all observations to the AAVSO International
Database using the name "T PYX".

Thank you in advance for your participation in this very exciting
campaign and for your contributions to this fundamental research!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

-------------------------------------------
SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:

http://www.aavso.org/observing/submit/

Labels: nova, variable star

# posted by Ian Musgrave @ 2:23 pm