[vsnet-alert 1090] V651 Mon - call for observation now!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

    I have received the following message from Rafael Costero, and forward
this with the permission of him and cited observers (via Costero).
Observations (though very difficult) right now are very critical in
understanding the current, extremely rare, fading episode of this unique
binary planetary nebula nucleus.   Any attempts are highly appreciated.

Regards,
Taichi Kato
--------------------------------------------------------------------------
From costero@astroscu.unam.mx Wed Jul 30 15:38 JST 1997
Date: Wed, 30 Jul 97 01:40:04 CST
Subject: V651 Mon

V651 Mon is now barely observable in the (cold) morning twilight (for those 
brave observers in the southern hemisphere). In spite of extremely difficult 
observing conditions, a few admirable observers secured some estimates before 
the object became truly unobservable in late May and mid-June, and again are 
now doing their best, weather permitting. They have recently obtained four 
very valuable estimates of the object. I consider their measurements very 
much worth being known by vsnet members, so asked for their consent to share 
the data with your organization, thanks to which I learned of the current 
occultation episodes on this interesting object (or are they over?). 
Their estimates are listed below: 

  V651 Mon (Last two months)
  Date		Mag.  Observer
YYMMDD(UT)  	(vis)	Code
___________________________________
970529.701	<13.2	JAN
970530.701	<13.2	JAN
970530.384	<14.4	Stu
970602.389	 12.0	Stu
970602.701	 12.8:	JAN
970603.361	 12.0	Stu
970604.363	 11.8:	Stu
970605.369	 11.2	Stu	!
970606.360	 11.3	Stu
970607.363	 11.3	Stu
970608.351	 11.5	Stu
970608.379	 11.6	Far
970610.343	 12.5:	Stu	!!
970615.347	<13.2	Stu	!!!
970617.344	 12.0	Stu	!!
970618.348	 11.8	Stu
970619.349	 11.4	Stu
970620.347	 11.2	Stu
970622.358	 11.2	Stu	!
------------------------------------
970723.775	 11.0:	Jo
970724.769	 11.2	Jo
970724.840	 11.4	Stu
970725.772	 11.3	Jo

Key to observers:
Far: Fraser Farrell	Jo: Albert Jones
JAN: Jan Hers		Stu: Rod Stubbings

Weather in Australian and New Zealander mornings has prevented any further 
estimates since July 25. It is very important to know if occultations are 
still  going on. My guess is that, if so, the object should be weaker than 
mag 12 or so any time between July 27 and August 5, or during all that time 
interval. I'm sure you will understand the importance to have at least one 
estimate during these days. Sure it's hard, the object beeing so close to the 
Sun; it is, I am sure, imposible for us northeners. But I call again for your 
very valuable help for the case of this very interesting object. With the 
moon now waning and comet Hale-Bopp not far from V651 Mon (about 12 degrees 
south and 10 min further east), the early-rising might worth the effort!

I am very much endebted to all those observers that had already tried and, in 
many occations, obtanied the valuable observations needed to know the nature 
of the occulting dust-cloud passing in front of V651 Mon, the ~16-day period, 
spectroscopic binary central star of the planetary nebula NGC 2346.

With my deep gratitude to you and all vsnet-ers,

Rafael Costero
Instituto de Astronomia, UNAM
P.O. Box 70-264
04510 Mexico, D.F.
costero@astroscu.unam.mx

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp