Defining the Cone Nebula

[scarp15]

NGC 2264, the Christmas Tree Cluster is a seasonal popular favourite, observed in Monoceros and bound within this cluster, there are regions of nebulosity. To the south of the cluster lies the variable star S (or 15) Mon, where on nights of excellent transparency, a faint glow of nebulosity can be seen. Below this lies the star HD 47887, where there is a vague haze (a large patch of nebulosity), containing to the south of this star, a dark indentation - this feature is the Cone. 

Considered to be harder visually to achieve than that of the Horse Head and not unlike B33, a dark cloud / notch / indentation is embedded in the dim surrounding nebula. Any chance for seeing this will at the very least require a dark transparent sky, potentially large aperture, complete dark adaption, at a time when Monoceros is high in the South. A H-beta filter is considered the means to best achieve this observation and my understanding is somewhere in-between 70 - 120x in magnification. I expect that there will also be a debate on exit pupil size, which I think should be at least 4mm. Seeing nebulosity around S Mon is considered as the Litmus test for seeing the Cone, just as determining good definition for the Flame is the gateway to an attempt to observe IC 434 and B33.  

I have not tried to observe the Cone with any real commitment and unless I gain access to a larger scope sometime, it will not necessarily become high on my agenda. Yet it would be interesting to debate what actually defines the Cone Nebula and what aspects of this or associated nebula SGL members who have tackled successfully or otherwise consider that they have achieved - if not the Cone, then perhaps specific associated ' brighter' nebula. This is just my understanding as to what constitutes the Cone nebula, I would like to hear your version on the subject and correct any inaccuracies.

Therefore what would you consider defines the Cone Nebula and what would you suggest is required for attempting an observation?

[m.tweedy]

You could try our 18.5 Dob Iain. You never know it may show in that.

[jetstream]

6 hours ago, scarp15 said:

Therefore what would you consider defines the Cone Nebula and what would you suggest is required for attempting an observation?

A few years of trying to see it defines this object for me. Success came thankfully and this one isn't easy-for me anyway. Helix has good information on the Cone and what can be seen, hopefully she will chime in.

Another excellent thread Iain.

[Stu]

Great post Iain, a very interesting read which will hopefully generate some helpful responses.

I can't add anything myself, except to say that, coincidentally I was observing the Christmas Tree Cluster myself last night. Only a 4" scope and mag 19 skies so no hope of any nebulosity but still a very nice Cluster.

The Cone does appear to be a particularly hard challenge, perhaps the next for members to focus on now that the Horsey seems to have been tamed  

[scarp15]

12 hours ago, m.tweedy said:

You could try our 18.5 Dob Iain. You never know it may show in that.

That's a thought Michael, is the 18.5 truss dob getting some good use, such as at Millshields or perhaps plans to take along to the Spring Kielder Star Camp? Around that size aperture and larger of course is most likely what is required to make this observation a little easier. Just slightly off topic, are the SAS meeting at Millshields this Friday for the Geminids if clear?

[scarp15]

6 hours ago, jetstream said:

A few years of trying to see it defines this object for me. Success came thankfully and this one isn't easy-for me anyway. Helix has good information on the Cone and what can be seen, hopefully she will chime in.

Another excellent thread Iain.

Look forward to your reports when you get your 24" dob out there Gerry.

6 hours ago, Stu said:

Great post Iain, a very interesting read which will hopefully generate some helpful responses.

I can't add anything myself, except to say that, coincidentally I was observing the Christmas Tree Cluster myself last night. Only a 4" scope and mag 19 skies so no hope of any nebulosity but still a very nice Cluster.

The Cone does appear to be a particularly hard challenge, perhaps the next for members to focus on now that the Horsey seems to have been tamed  

Cheers Stu good that you got to observe the Christmas Tree Cluster, I look forward to this to. I have read on Cloudy Nights of the Cone being observed very vaguely in 10" to 14" scopes but realistically 18"+ for the UK would be a more reasonable approach, although I have not seriously tried with my VX14. Yes good question, after gaining the Horse Head where do you go from there? Lots of challenging Sharpless catalogue subjects, which are not necessarily in the realm of the big dob.

[Stu]

2 hours ago, scarp15 said:

Look forward to your reports when you get your 24" dob out there Gerry.

Cheers Stu good that you got to observe the Christmas Tree Cluster, I look forward to this to. I have read on Cloudy Nights of the Cone being observed very vaguely in 10" to 14" scopes but realistically 18"+ for the UK would be a more reasonable approach, although I have not seriously tried with my VX14. Yes good question, after gaining the Horse Head where do you go from there? Lots of challenging Sharpless catalogue subjects, which are not necessarily in the realm of the big dob.

I have a secret 10" mirror and secondary spider hidden away somewhere; really need to get a Truss dob built so I can see what I can do with that.

[Paul73]

Tamed Horsey???? ???

This one should be nicely placed for the next few months. There are a lot of Big Dobers who haven’t cracked this one.

Has anyone managed it from the UK?

Paul

[PeterW]

Yes, once with large dob, also with smaller dobs too. Need good transparency.

Stu I have some optics that need scoping too, maybe we should join forces?

 

peter

[scarp15]

The weekend forecast looks like its going to be a good one again up here, will take the VX14 out and determine if at least associated nebula can be observed. 

[Stu]

2 hours ago, PeterW said:

Yes, once with large dob, also with smaller dobs too. Need good transparency.

Stu I have some optics that need scoping too, maybe we should join forces?

 

peter

Good plan!

[Mark at Beaufort]

Nice thread Iain. I have the feeling that members of the Dob Mob recently had a go at the Cone. Perhaps they will come along shortly and report their efforts.

[Doc]

According to my notes:

22nd Dec 2009
Meade Lightbridge 16" F4.5 Fl 1829mm
Slight Crescent Moon gone by 21.30
Very cold -1° to -4°

Next onto Ngc2264 The Christmas Tree Cluster in Monoceros, this is such a delightful cluster and really does look like a christmas tree, in the 28 Uwan at x65 I counted approx 30 stars many over mag 8 in brightness. Around the bright star at the base of the tree there is alot of nebulosity which with averted vision has a triangular or cone shape cut out. With prolonged observing the nebulosity seems to stretch further into the tree but this is very subtle. I cannot be sure I saw the cone nebula but with averted vision and the 7 Uwan inserted I might have.

[John]

Very interesting thread and a tough challenge indeed !

I seem to recall that I have tried to see the Cone a couple of times but not with any real "vigour". As I'm now getting the Horsehead in my 9x50 finder every other night () I'll take up the Cone challenge again

 

 

 

[alanjgreen]

Last night (in a clear "hour") I popped out for another crack at the cone in a "race against the clock" session (using 20" dob).

I had some success on 10 December, with 13Ethos (scope fl with paracorrr =2089 so x150 mag) and O3 filter - the seeing was good on that occasion. There had been plenty of nebulosity around 15Mon and plenty more to the right side of the cone. It was late in my session and I was cold, as was the rest of my kit and so I was stuck with what I had in the scope at the time.

See

Last night, as I was "straight outside" (with all equipment warm and useable) I tried Ethos8, 10, 13 & 21 paired with Astronomik UHC, O3 and Hb. The seeing was not as good, NGC891 (galaxy) was a lot less giving than it had been on 10 Dec (I checked this first off).

In the Ethos8, the cone looks like it should fill the FOV (x250), the cone area was nice and black but the view lacks the nebulosity to the side so you can "get your eye in". Similar with the 10mm.

The 21mm provided a less dark background so I decided that 13mm was the best chance.

With the O3 and Hb then nebulosity is easily seen around in the area. With the UHC less so.

There was a nice "glow" around the double star at the tip of the cone. With averted and staring the "straight right side" seemed to come and go. At one point I thought I saw a "gap" open up between the cone blackness and the double star (but only glimpsed) as the cone does not come all the way up to the double star.

In conclusion, I did not "see" the cone last night but I was maybe an hour too early for it to be best placed for me & the seeing was off. I will be back for another crack on Friday when it is forcast clear. Hopefully this little practice will help me out then?

Interesting that @Doc saw it in a 7mm EP, so maybe I will keep trying with the Ethos8 too ...

[Stu]

Nice one Alan. I'm assuming you are referring to transparency being poor rather than seeing? I know high power is being used so potentially both are important, but poor transparency is what normally kills galaxies and nebulosity off.

Just checking for my own understanding. Might try and buy one of those finders John has got....  

[scarp15]

7 hours ago, alanjgreen said:

In conclusion, I did not "see" the cone last night but I was maybe an hour too early for it to be best placed for me & the seeing was off. I will be back for another crack on Friday when it is forcast clear. Hopefully this little practice will help me out then?

Interesting that @Doc saw it in a 7mm EP, so maybe I will keep trying with the Ethos8 too ...

Friday forecast looks excellent Alan, (north Cumbria, north east), look forward to hearing how you get on.

[scarp15]

The size of the Cone, its dark mass, is very similar to that of the Horse Head, so I have read. I think that I might experiment with a variety of eyepieces to include 20mm and 25mm plossl's (x92 / 3.78mm exit pupil, x74 / 4.72mm exit pupil) as well as ultra wide 21mm and 13mm. I have read accounts of up to 6mm exit pupil being used, quite a variation it would seem from between low to medium / high power. Could become an interesting session, warming up the eye towards some familiar targets to begin such as NGC 2174 Monkey Head nebula and regardless of the outcome, facing the right way for any Geminids. Good luck for anyone able to get out on Friday night.

[estwing]

[estwing]

https://www.skyhound.com/observing/archives/jan/NGC_2264.html

[estwing]

http://www.deepskyforum.com/showthread.php?678-Object-of-t-he-Week-January-25-2015-NGC-2264-the-Cone-Nebula

[scarp15]

I have that page (Skyhound) printed, in conjunction with Interstellarium Deep Sky Atlas, that chart may be helpful.

Edit: I had not read that deep sky forum account, interesting that observations are possible within SQM 21.4 skies, which is typical to some of my observing locations. My scope maybe a little too modest in aperture ambition, it would be interesting to explore the area, perhaps at least resolving certain aspects of the surrounding nebula. 

[estwing]

worries me that folks with 24"+ struggle on good nights....all down to the skies Iain

[PeterW]

If Owen found it hard then we may need to start munching on more carrots....

 

peter

[scarp15]

Yes as Ronnie Corbett had once said "I know my place".