Sky & Telescope - December 2024 - 31

NGC 2300 GROUP IN VISUAL: POSS-II / STSCI / CALTECH / PALOMAR OBSERVATORY;
NGC 2300 GROUP IN X-RAY: NASA
NGC 2300
IC 455
NGC 2276
HD 51141
IC 469
LITTLE GROUP NGC 2300 anchors a group of several galaxies. The
interactions between the members have bent several galaxies out of
shape, including NGC 2276, as shown on pages 26-27.
NGC 2268
HOT GAS This X-ray image obtained in 1992 with the German-led
project ROSAT (Röntgensatellit) shows that the galaxies of the NGC 2300
group are embedded in a hot gas, which is a tracer of dark matter.
Sharing the 25′ field with the galaxy pair is IC 455, a
small, 13th-magnitude lenticular that has a brighter core and
appears slightly elongated almost east-west. Edward Emerson
Barnard observed it in 1890 a month before Denning, but
because he never reported the find it's Denning who receives
credit in the Index Catalogue. It's interesting to contemplate
that two great observers were observing the same area of sky
at about the same time: Barnard with a 12-inch refractor at
the Lick Observatory in California and Denning searching
for comets with a 10-inch reflector in England. While Barnard
was rather sensitive about the priority of his discoveries,
he failed to report them on several occasions, a fact that Denning
was critical of in later life.
Jump 43′ southeast of NGC 2300 to land on IC 469,
which lies centered in a triangle of 9th- and 10th-magnitude
stars. A 13th-magnitude barred spiral, it's elongated along its
east-west axis and has a small, bright core. This is another of
Denning's 1890 discoveries in the area.
Denning also discovered our next galaxy pair. IC 499 and
IC 512 are separated by just 25.6′. But as they don't quite
fit together in my preferred field of view, I can relate to the
circumstance that led to him finding them some two weeks
apart in August (IC 512) and September (IC 499) of 1890.
From IC 469, slide some 1.2° northeast into Camelopardalis
to arrive at 12.5-magnitude IC 499, the closest IC object to
the north celestial pole - you should spot it 1.2′ southwest of
a 12th-magnitude star. An oval elongated almost east-west, I
see the object as fairly faint with low surface brightness but
with a brighter core. A 14th-magnitude star lies southwest
of the center. Slew about 25′ southeast of IC 499 to arrive at
12.2-magnitude IC 512, which appears almost round with
a very small brighter core. The halo has a rather blotchy
appearance. Denning first took this object to be a comet and
concluded it was a new nebula only after verifying that there
was no movement over a prolonged observation.
Moving Farther Afield
For our next stop, begin back at NGC 2300 and drop 3.3°
south to the 5th-magnitude variable star VZ Camelopardalis.
NGC 2336 is another 2.2° south of that marker and forms
a triangle with 10th- and 11th-magnitude stars off its west
side. Tempel discovered the 10th-magnitude galaxy in 1876
while observing at Arcetri Observatory. NGC 2336 is a giant
spiral ring galaxy: A star-forming ring encircles the central
bar - in fact, a 2018 journal article published in Monthly
Notices identified 78 star-forming regions in the ring and
spiral arms!
This fairly large galaxy is oriented nearly face-on and elongated
north-south. It has a small, gradually brighter core with
a strong central condensation. At 139×, the spiral arms show
as an extended halo that appears dappled and brighter to the
north. A 15th-magnitude star is just east of the core.
sk yand tele scope .o r g * DECEMBER 2024 31
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Sky & Telescope - December 2024

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