[vsnet-chat 3547] Re: Mon v651

["Stan Walker" <astroman@voyager.co.nz>]

Greetings,

The mention of V651 Mon (NGC 2346 in those days) brings back old memories.
In respomse to the article by Kohoutek (or perhaps an earlier mention by one
of the CV people)
we began an observing campaign in Auckland in 1982. It was unsuited to pep
so most
of the observations were by Harry Williams using a 54cm telecope
and a conventional camera with a yellow filter to reduce the PN
input. Reductions were made by Brian Marino. At the time the central binary
was also being obscured by something in the nebula itself so the light curve
appeared spectactularly eclipse-like. To add confusion, after a year or two
the phase of
the obscuration changed with the movement of the cloud. I made some UBV
measures at the time but they were difficult due to the bright (to the pm
tube) background. Such stars would make ideal objects for CCD measures,
provided that care was taken with the reductions. Automatic software using a
concentric sky background  might have problems.

Warner discusses these stars in 'Cataclysmic Variables' and gives a list of
34 pre-cataclysmic variables of which 10 are PNs. Two of these are 15.9 and
16.5 but the rest are reasonably bright. Most of the periods are 1-2 weeks
although MT Ser is 2.7 days at V = 15.4.

I think, from memory, that visual observers (RASNZ VSS) also tried these
objects but the
results were confusing and were not used in any of the analyses. So it's
best to use old
style photography or CCD imaging.

We've looked a few times since then but the spectacular behaviour of the
1980s has not recurred. And, I must admit to not having thought of CCD
measures.

Regards,
Stan


----- Original Message -----
From: <Afoevb@aol.com>
To: <vsnet-chat@kusastro.kyoto-u.ac.jp>
Cc: <mikesimonsen@mindspring.com>
Sent: Thursday, August 17, 2000 1:51 AM
Subject: [vsnet-chat 3546] Mon v651


> In vsnet-chat 3543 (unusual variable objects), M. Simonsen asked what is
the
> story behind V651Mon and are there more PN like it that are observable by
> amateurs? In the Sonneberg List I found for v651 Mon the reference :
> SCHAEFFER, PASP 98, 556, 1986. In our "Bulletin de l'AFOEV" (no 31, 1985)
Dr.
> A. ACKER (Strasbourg Observatory) wrote an article (in french) on "the
> evolution of the light curve of the central star of the PN NGC 2346" (If
M.
> Simonsen send his postal address, I am glad to send a copy). In bulletin
no
> 26, Dr. ACKER wrote an other article on this star and refered to L.
Kohoutek,
> IBVS 2113 (1982), Dr. Mattei, AAVSO Alert Notice 58 (1983) and B.
Schaeffer,
> IBVS 2281 (1983). She suggested the observation of the folowing objects
> FC      PK          NP          AR          dec (1950)  mv
> 28      165-15°1    NGC 1514    04:06:08    +30:38.7        9.5
> 43      215-24°1    IC 418  05:25:10    -12:44.3        9.7
> 74      215-24°1    AG-0 965    07:06:50    -00:43.5        11.3
> 86      235+1°1 VV1-7       07:39:01    -18:52.6        8.3
> 148 303+40°1    A 35        12:50:51    -22:36.1        9.6 = LW Hya
> 149 339+88°1    LoTr 5  12:53:08    +26:09.7        8.7
> 156 318+41°1    A 36        13:37:58    -19:37.6        11.5
> 279 96+29°1 NGC 6543    17:58:34    +66:38.1        9.6
> 350 50+3°1  M1-67       19:09:17    +16:46.5        11.2
> 381 25-17°1 NGC 6818    19:41:10    -14:16.4        13.0
> 383 83+12°1 NGC 6826    19:43:27    +50:24.2        10.2
> 403 54-12°1 NGC 6891    20:12:48    +12:32.9    11.8
> Charts were extract from "Catalogue of central stars of true, probable and
> possible planetary nebulae"
> E. Schweitzer - AFOEV
>
>

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