Re: (IAAC) The interesting question of the Christmas Tree and the Cone

	working from the original NGC Dreyer says "15 Monoc, CL,**, ? neb". He
gives no size and no indication of any other neb. The discoverers are down
as William and John Herschel and I doubt with their mirrors they could have
seen the cone itself. There is emission nebulosity surrounding 15 Mon so I
guess that is what they are talking about. Interestingly in the IC2
supplement there is an additional set of notes.

"Delete the ? An eL neb 3 deg+- in diam, the densest part is 12' sp the
star 15 Monoc. Barnar Astr and Astrophys, xiii p 178; MN lvi p 63 and lix p
364; Roberts ibid lv p 398" 

As the cone is quite small it may not  have fitted Barnards catalogue. He
did not include other dark nebulosity that were already known either. I am
not sure who gave the Cone its name but that might help with who first
saw/photographed it. From the above references I would guess either Barnard
or Issac Roberts.

At 19:59 14/09/2001 -0400, you wrote:
>A recent short thread on IAAC centered around the best designation to use in
>refering to the strange, somewhat challenging Cone Nebula in NW Monoceros. It
>is very close to the lovely, visually *stunning* open cluster commonly known
>as the Christmas Tree cluster. The OC is clearly included in entry "2264" of
>Dreyer's New General Catalog, and the question naturally arose whether the
>Cone should also be associated with it, as a part of an "NGC 2264 complex".
>(The Cone also seems to have its own designation as LDN 1613, just as the OC
>and bright nebula have their special designations: Collinder 112, Melotte 49,
>S Monocerotis cluster, Sharpless 2-273, Lynd's Catalog Bright Nebula 76, etc.
>Many thanks to Jeff Bondono's 'dObjects' database, as always, for this info.
>BTW, I also raised the question of why the Cone was not included in the large
>Dark Nebula catalog published by E. E. Barnard. But that is another topic!)
>In response to this thread, I received a private communication from a very
>well respected source in deep-sky observing and identification, the gist of
>which was, "Given that NGC 2264 is half a degree away from the Cone, and the
>Cone has nothing to do with the Christmas tree cluster/asterism, obviously
>the NGC designation has nothing to do with the Cone." This was both welcome
>and helpful information, and yet it got me wondering...
>The original Dreyer description of N2264 (so far as I can glean it from other
>sources) seems to contradict this statement, as it both describes NGC2264 as
>actually consisting of both a Cluster and Nebulosity (C+N), and further, says
>the associated nebula stretches WELL beyond - actually engulfing - the Cone:
>>Type: C+N.
>>Description: eL neb, 3deg diam, densest 12' sp 15 Mon
>On the other hand, the NGC/IC Project database lists the cluster's size at
>just 20' - falling well short of the "top" (S vertex) of the Christmas Tree,
>and therefore of the Cone. This certainly seems to corroborate the source!
>What is more, the NGC/IC database entry (below) makes no mention of a member
>of the Lynd Dark Nebula Catalog (LDN) being involved with NGC 2264:
>>Cluster w/nebulosity
>> ...
>>LBN 911, Mel 49, OCL-495, Lund 246, Sh2-273,
>>H VIII-5, H V-27, h 401, GC 1440
>(Thanks to the folks of http://ngcic.org for that wonderful resource, BTW!)
>And yet, an examination of the Digitized Sky Survey (First Generation) adds
>to the confusion: a 60'-wide image centered on the Christmas Tree, clearly
>shows it embedded in (or at least visually suffused by) a large complex of
>nebulosity, just as Dreyer's description would indicate... And sure enough,
>impinging on this suffusing nebulosity, without any visible break, one sees
>the deep, dark cut of the Cone Nebula: it *appears* to be clearly involved.
>In the final analysis, it is possible a professional may choose to conclude
>that the dark nebula is in the foreground, and superimposed on the complex of
>bright nebulosity and cluster stars that are part of NGC 2264. (But is this
>actually the case? My own inexpert search for Abstracts turned up one or two
>papers which discuss the Cone as part of N2264, e.g. "1987A&A...181..112P".
>Then again, other references turned up by the same search were more vague.)
>But in any case, the NGC does double duty: as a referent catalog used in
>professional research papers, and as observing guide for amateur deep-sky
>observers and imagers the world over. From the amateur's perspective, it
>seems very tempting to include the Cone (LDN1613) with the Cluster (N2264).
>I welcome comments from others, especially the many folks on our list more
>experienced both in observing, and in catalog history and identification...
>Luckily, we Northern Hemispherians will have many long Winter months ahead,
>to enjoyably debate and consider such fine points of identification. :)
>Clear skies, and THANKS to all who contributed to this thread so far!
>Lew Gramer
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