Sky & Telescope - March 2024 - 57

BERNHARD HUBL
Also visible, barely, is an 11.3-magnitude
star inside the triangle. Hallelujah!
- that teeny-weeny dot belongs to NGC
2420. Provided I cup my hands around
the eyepiece to block out stray light, and
scan the field with averted vision, I can
usually perceive the cluster as an illdefined
yet tantalizingly granular mist.
This grainy texture becomes more evident
when I increase the magnification
to 93×. Detecting these subtle features
proves that NGC 2420 isn't completely
beyond the range of my smallest scope.
Faint praise, I know.
Thankfully, NGC 2420 improves
with more aperture. My 7.1-inch MakCass
cruising at 90× picks up six family
members. The three brightest outline
a roughly equilateral triangle, a couple
of arcminutes wide, in the southern
portion of the distinctly grainy mist.
Doubling the power gives me up to nine
more stars down to at least magnitude
12.5. I'm uncertain about the total
number because some of those dim
flecks waver at the threshold of visibility.
NGC 2420 puts on a brave face in
my 10-inch. At 48×, the Dob shows the
seven-star neighborhood clearly, and a
mottled patch in the correct location
establishes the cluster. Boosting the
magnification to 95×, the six brightest
stars in the patch are obvious, including
the embedded equilateral triangle
mentioned earlier. When I push the
scope to 169×, NGC 2420 yields 12
stars, maybe 15 during instants of
steady seeing. Admittedly, the three
most feeble pinpoints are " difficult to
hold " in deep-sky-speak.
Ultimately, my Trusty Ten produces
no additional threshold stars beyond
what the Mak-Cass shows, but the extra
aperture resolves the coarse scattering
better and slightly intensifies the grainy
background mist. Indeed, by staring
patiently for several minutes with
averted vision, I get tantalizing hints of
a densely populated cluster. NGC 2420
isn't a phantom after all! I'll take it.
Satisfaction Guaranteed
I'd like to suggest one final bit of
sightseeing. Two stars hang about ¼°
south-southeast of NGC 2420. The
pREMOTE CLUSTER Approximately 9,000 light-years from Earth, the relatively old open cluster
NGC 2420 is populated with hundreds of intrinsically dim stars. NGC 2420 is no match for the
famous Double Cluster in Perseus, which is only slightly closer yet appears much brighter.
9.3- and 9.6-magnitude suns, about
80″ apart, catch my attention because
of their warm hues. The brighter one
radiates yellow-orange, the other is
closer to pure yellow. These amber
lights, together with a 10.2-magnitude
star northward, make a skinny triangle
that's a miniature version of the slender
shape framing the diminutive cluster.
Yes, NGC 2420 is one tough target
for suburban scopes. My attitude is
to embrace the challenge. By applying
just enough magnification to spot the
cluster's triangular neighborhood, then
additional power to nail the cluster
itself, I can honestly say I enjoyed a
worthwhile observing experience.
Detecting stuff at the threshold of visibility
might not be exciting, but it sure
is satisfying.
¢Despite the quality of his night sky,
Contributing Editor KEN HEWITT-WHITE
likes star clusters of all kinds.
A Gemini Neighborhood
Object
Type
Castor AB
Castor AC
κ Gem
Σ1124
Double star
Double star
Double star
Double star
VAS 14 AC Double star
VAS 14 AD Double star
VAS 14 AE Double star
NGC 2420
Open cluster
Mag(v)
1.9, 3.0
1.9, 9.8
3.7, 10.0
9.1, 9.3
9.1, 10.9
9.1, 11.3
9.1, 10.4
8.3
Size/Sep
5.6″
71.6″
7.0″
19.3″
78.3″
106.3″
125.9″
6.0′
RA
7h 34.6m
7h 34.6m
7h 44.4m
7h 41.0m
7h 41.0m
7h 41.0m
7h 41.0m
7h 38.4m
Dec.
+31° 53′
+31° 53′
+24° 24′
+21° 28′
+21° 48′
+21° 48′
+21° 48′
+21° 34′
Angular sizes and separations are from recent catalogs. Visually, an object's size is often smaller than the
cataloged value and varies according to the aperture and magnification of the viewing instrument. Right
ascension and declination are for equinox 2000.0.
sk yand tele scope .o r g * MARCH 2024 57

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Sky & Telescope - March 2024

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