Calabash nebula observation

Hi All,

Steve Gottlieb, Jerry Morris, Jim Chandler and I had a positive observation of the Calabash Nebula last Friday night with my 48"F/4 reflector.

RA
07 42 16.8

DEC
-14 42 52
Attachment 96

The Calabash nebula is a protoplanetary near NGC 2438 in M46 it is bracketed between a 13.7 V MAG star and a 13.2 V MAG star and on one end of the nebula is a 16.7 V Mag star. The nebula only appeared with averted vision and the best view was with a 7MM TMB supermono at 697X unfiltered. It looked a lot like a very faint edge on galaxy and in moments of good seeing it looked to my eye to be approximately 27" long. I did not see any hint of the bright knot in the image. I tried a DGM NPB filter with no results. I hope Steve Jerry and Big Jim will share there observations here.

Attachment 97

Hi Jimi,

great observation of the "Rotten Egg/Calabash". I tried the ProtoPN several times with different aperture up to 27" but could not see any elongation. The minimum aperture was 16" - I could see a very faint stellar spot of light which I could hardly hold with averted vision.

I asked Brian Skiff about the magnitude of the deeply buried central star -- QX Pup -- which is a variable discovered in the infrared. He responded the magnitude is down around V = 18.5-19 (at least currently), so unlikely to be seen visually. But according to a AAVSO page on QX Pup (http://www.aavso.org/qx-pup), the reflection off of the bipolar nebula mimics the variation of QX Pup, so it's very possible the nebula may be brighter at other times and easier to view than our experience.

By the way if anyone else wants to give the Calabash Nebula (AKA the Rotten Egg Nebula), the position is just 6.5' ENE of the annular planetary NGC 2438 in M46!

Steve,

This is the USNO image that you sent me.
Attachment 107

It sounds like this object needs to be looked at periodically. I would really like to see it in outburst! I am going to keep a eye on it for a while,do you know when the last outburst was?

Uwe you might want to keep a eye on it also with your 27".

I viewed the Calabash on 4-20-12 with my 32" at TSP. Using a Type 6 Nagler 5 mm eyepiece at 650X I was able to see the central star and suspected the nebulosity that extends to the north and south for several arcseconds. The part to the north, which to me appears as the "top of the bowling pin", is quite visible on the POSS 2 red plate and I was able to see that, almost more clearly than the central, obscured area containing the evolving star.

The next night at Jimi's 48" I stole a peek as we were examining NGC 2438, and had about the same view, with a sky inferior to the 20th.

Dave Tosteson

This article was published today about this proto-planetary nebula:

http://aasnova.org/2017/07/26/the-ma...netary-nebula/