Sky & Telescope - January 2024 - 16

Overlooked Nebula
NGC 2071
HD 290860
HD 290861
HD 38563
HD 290862
M78 = NGC 2068
EM* LkHA 309
EM* LkHA 312 and
EM* LkHA 313A
NGC 2067
LDN 1627
CXOU J054635.3+000858
and VSS VI-4
The Main Nebula and Friends
M78 is the largest and brightest region of nebulosity, and it's
what the three pioneering observers referred to above saw.
However, the first part of Messier's description doesn't really
match modern views of M78. Not only is there no star cluster
here, but there's also a noticeable lack of them around M78.
This has me wondering why he described it as a " cluster of
stars. " Where Messier quotes Méchain, though, is spot on,
and Herschel's precise notes confirm he was seeing M78, too.
Although my 28-inch sketch (on page 15) shows exactly
what I saw, let's go through some of the highlights. Notice
the sharp but slightly uneven northern boundary M78 makes
with the curved dark nebula LDN 1627. I saw one definite
PM J05472-0000
[SSC75] M 78 11
NGC 2064
notch and perhaps glimpsed another. To paraphrase Herschel,
" I am not quite so well assured of [its] reality, " but I did have
the impression that the northern border of NGC 2068 was
somewhat serrated.
The two lights illuminating M78, which I first saw with my
McNeil's
Nebula
V2764 Ori
EM* LkHA 301
[B77] 106
8-inch scope, stand out as equally bright and conjured a pair
of stellar eyes within a ghostly face. The northernmost star,
10.8-magnitude HD 38563, is a close double that I saw as a
single object, while the southern star, HD 290862, is a YSO
and is slightly brighter at magnitude 10.4. The third star that
Herschel mentioned, just south of the brightest part of M78,
is 13th-magnitude [SSC75] M 78 11.
The three seemingly nondescript stars trailing off to
LABELED NEGATIVE OF THE SKETCH Note that nearly every star is
a type of youthful star! Some sources place NGC 2064 within the outer
reaches of NGC 2068, but its actual location is as shown.
My notes from the first night read:
Two main clumps of nebulosity with an irregular arc of clumpy
nebula arcing around the brightest of the main areas. With the
curved dark lane highlighting the pervasive background glow -
which seems rather patchy - this is a lovely sight! 155×, 408×,
21.81 SQM [Sky Quality Meter]
On the second night I noticed two small nebulous glows
along the southern end of M78's extended nebulosity. I didn't
know their designations at the time, so I wondered if one
of those two knots might be McNeil's Nebula, a variable
nebula that American amateur Jay McNeil discovered photographically
in 2004. His object is reminiscent of a smaller version
of Hubble's Variable Nebula (NGC 2261). The illuminating
star for McNeil's Nebula is the protostar V1647 Orionis,
which, at magnitude 18.1, is very difficult to see.
After returning home, I looked up the location of McNeil's
Nebula and quickly confirmed that I hadn't seen it. Evidently,
no one has since 2018, but at least I know where to look for it
now. However, I did see quite a bit more of M78 and its surroundings,
and they proved to be plenty interesting.
16 JANUARY 2024 * SKY & TELESCOPE
the southeast from M 78 11 turn out to be rather interesting.
In descending order of brightness, we have the highproper-motion
star PM J05472-0000; the T Tauri star
EM* LkHA 309; and a close double comprising a YSO,
EM* LkHA 312, and a T Tauri star, EM* LkHA 313A, that
I saw as a single object. Don't dismiss stars in this region at
first glance - many turn out to be fascinating once you dig
into their true natures.
To my eye, LDN 1627 - as the dark backbone of this area
- helps define the northern and northwestern edges of M78,
while in the opposite directions its bright nebulosity gradually
fades to the south and east. The dark nebula is as visually
important as the bright portions, and I imagine it's brightly
illuminated all along its far side. In fact, it doesn't disappear
completely, because the entire area is dappled with a subtle
mix of dark and barely detectable bright nebulae, with the
most noticeable part straggling off to the south.
The Northern Area
NGC 2071 connects to the northern reaches of M78 by
the subtle and uneven glow of background nebulosity that
suffuses this area. It gives the strong impression that all the
brighter nebulae are part of the same complex and separated
by dark nebulae. The brightest part of NGC 2071 is punctuated
by the star HD 290861, a 10th-magnitude YSO.
The nebula surrounding HD 290861 is roughly circular,
colorless, but with noticeably irregular edges. It gradually
dims the farther it gets from the star until it joins the background
glow to its south and northwest, where it brightens
Sky & Telescope - January 2024

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