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Special Notice #254: T Pyx Campaign continues

September 10, 2011:  The outbursting recurrent nova T Pyx is past solar conjunction and is widely observable again. Arto Oksanen in Finland has been following it through July and August and reports it currently at 10th magnitude. Please add T Pyx back to your observing schedule if possible to follow the decline of its outburst. See AAVSO Alert Notice 437 and AAVSO Special Notice #244 for details on the T Pyx campaign organized by Dr. Brad Schaefer (Louisiana State University).

To see the impressive light curve of the current outburst of T Pyx to date, use the AAVSO Light Curve Generator.

Dr. Schaefer wants to continue the campaign until T Pyx has completely returned to minimum, and asks for ongoing coverage by AAVSO observers. He reports that the 2011 eruption has not been following the 1967 light curve for the past few weeks, so its future behavior is somewhat uncertain. In 1967, T Pyx took about 230 days to return to minimum from its outburst. As the 2011 outburst began April 14, T Pyx should return to minimum with a few months or so, even allowing for deviations from the 1967 pattern.

Dr. Schaefer writes: "My highest preference observations would be CCD time series for the whole time T Pyx is available, all in the V-band. Second preference would be to cycle back and forth between BVRI (or some combination) for time series in color.  My third preference would be for BVRI (or some combination) with CCD at one time each night. My fourth preference would be for V (or visual) magnitudes once a night.

"To make for a uniform magnitude scale by everyone, please use the following comparison stars:

COMPARISON: AAVSO="115" CD-31 6884  09:04:43.8  -32:24:47 B=12.12, V=11.52
CHECK:          AAVSO="125" 000-BBQ-223 09:04:35.7  -32:22:41 B=13.217, V=12.495
COMP2:          AAVSO="143" 000-BBQ-225 09:04:40.2  -32:22:03 B=14.903, V=14.285
Variable star:  AAVSO="84"  HD77938        09:04:29.5  -32:26:54 B=9.49, V=8.44, do not use

"Please use the COMPARISON star (AAVSO="115") for the differential photometry. Use the COMP2 star (AAVSO="143") as T Pyx returns to minimum.

"The reason for the time series is to look for flares (as first discovered for U Sco), and to pick up the start of the orbital modulations (on 1.7 hour periods).

"The science questions for the 'tail' of the eruption are (1) how is this different from 1967 {and then this needs an explanation from theorists}, (2) when does the orbital modulation appear and does it have a phase shift, and (3) what will the quiescent level be {this will tell a lot about the V1500 Cyg mechanism}."

Coordinates: RA 09 04 41.5  Dec -32 22 47.4 (2000.0)

Finder charts for T Pyx may be plotted using the AAVSO Variable Star Plotter (VSP).

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

This Special Notice was compiled by Elizabeth O. Waagen.
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