Sky & Telescope - December 2024 - 30

POSS-II / STSCI / CALTECH / PALOMAR OBSERVATORY
Northerly Targets
ence, Italy, with an 11-inch refractor. It's the most northerly
object attributed to him and the second-closest NGC object
to the north celestial pole.
Continue another 3.9° southeast to arrive at 12.9-magnitude
IC 442. My 30-inch Dob at 390× shows the hint of
a double nucleus in this small, round galaxy. There is no
sign of that feature in my 18-inch, which reveals only a very
slightly brighter center. British amateur astronomer William
Denning discovered this galaxy using a 10-inch reflector on
November 9, 1890.
From IC 442 turn north-northeast and slide 1.7° to reach
NGC 2268, an 11.5-magnitude barred spiral elongated
east-northeast to west-southwest. It appears fairly large and
relatively bright with a brighter core and a faint outer halo.
Observing from Marseille Observatory, French astronomer
Alphonse Borrelly discovered NGC 2268 in 1871 using a 7.2inch
comet-seeker.
At around the same time and using the same telescope,
STAR-HOP TO A PAIR You can use 6.9-magnitude HD 140363 (bottom
center) to star-hop to the 13th-magnitude elliptical IC 1143 (the
smudge left of center, arrowed) and the 12th-magnitude spiral IC 1139
(above IC 1143). How many of the fainter (magnitudes 15 to 16) galaxies
around this pair can you spot in your eyepiece?
position for the object, but the galaxy currently designated
NGC 5640 is nearest to his position.
Extending the Little Dipper's Handle
Following the arc of the Little Dipper's handle another 3.2°
from Polaris and into Cepheus, we find NGC 1544, a 13thmagnitude
spiral that appears round with an almost stellar
nucleus. A close pair of stars around magnitude 14.5 mark its
northern edge. German astronomer Wilhelm Tempel discovered
NGC 1544 in 1876 from Arcetri Observatory near FlorHistorical
Sources
The author has dipped into several online resources to
dig up the chronologies and historical facts connected
with the giants of visual observing. Below we list the
webpages of astronomy historian Harold Corwin,
visual observer extraordinaire and history sleuth Steve
Gottlieb, and German astronomer and author Wolfgang
Steinicke. If you're interested in the ins and outs of the
discoveries, cataloging, misidentifications (and more!) of
the NGC/IC objects, then these sites are for you:
http://haroldcorwin.net/ngcic/
https://is.gd/astronomy_mall
https://is.gd/steinicke_ngcic
Borrelly also came upon NGC 2300, which lies 1.4° northnortheast
of NGC 2268, but he missed nearby NGC 2276,
only 6.3′ to the west-northwest. It was German astronomer
Friedrich August Winnecke who discovered NGC 2276 about
five years later; he also independently noted NGC 2300.
The pair are the brightest members of a small group of
galaxies dominated by NGC 2300. There's strong evidence
of interaction between members of this group - in fact,
they're both listed in Halton Arp's Atlas of Peculiar Galaxies.
The NGC 2300 group was the first in which an X-ray emitting
intergroup medium was observed, thought to be related
to, among other things, shocks driven by merger events.
NGC 2276, in particular, contains several ultraluminous
X-ray sources. I, however, couldn't detect any visible evidence
of interaction at the eyepiece.
An article published in 2016 noted that the NGC 2300
group was " out of synch " with regard to stellar ages. Contrary
to expectations, the core regions of the galaxies closer to the
center of the group comprise younger stars than the spirals
on the periphery, which have much older nuclei and bulges.
In my scope, 11.0-magnitude NGC 2300 appears oval
with a bright core and a faint outer halo. NGC 2276 is an
11.4-magnitude, open-faced spiral of fairly low surface
brightness, a sharply brighter core, and a mottled outer halo.
An 8th-magnitude star (HD 51141) lies just 2.2′ to the southwest,
where it tends to overwhelm the galaxy.
30 DECEMBER 2024 * SKY & TELESCOPE
http://haroldcorwin.net/ngcic/ http://adventuresindeepspace.com/steve.ngc.htm http://www.klima-luft.de/steinicke/ngcic/ngcic_e.htm
Sky & Telescope - December 2024

Table of Contents for the Digital Edition of Sky & Telescope - December 2024
