Sky & Telescope - April 2025 - 60

LEGACY SURVEYS / D. LANG (PERIMETER INSTITUTE) / CC-BY-4.0; SKETCH: UWE GLAHN
APRIL 2025 OBSERVING
Going Deep
TYC 3009-19-1
SHAKHBAZIAN 1 The first galaxy group
Romela Shakhbazian identified lies between
the hind paws of the Great Bear. It's the most
challenging collection described here - Glahn
sketched the four brightest members using his
27-inch under pristine conditions.
SHK 1-1
my 18-inch - a ghostly bead of light less
than 3′ southeast of 10 Com.
Next up is SHK 352, which occupies
a cramped 2.5′ × 1.5′ plot of celestial
real estate nearly 700 million lightyears
away. To locate our target, point
towards Tau (τ) Leonis, also known as
84 Leonis, in the southeastern corner
of the constellation. Tau consists of a
wide pair (1.5′ separation) of 5.1- and
7.5-magnitude stars tinted light yellow
and blue. It forms a binocular " doubledouble "
with 83 Leonis, a neighboring
pair 20′ northwest of Tau and consisting
of 6.6- and 7.5-magnitude stars
29″ apart. From Tau, scoot 1.7° to the
west-northwest, and you can't miss
10.4-magnitude NGC 3640. SHK 352
lies just 22′ to its south-southwest.
Through my 24-inch Dob at 380×,
I found a clump of four petite galaxies.
SHK 352-1 appeared as a faint, gray
stain measuring at most 20″ × 15″. Three
smaller and dimmer spots, SHK 352-2,
SHK 352-3, and SHK 352-4, adjoin its
north and east. Moving 5′ south of SHK
352-1, NGC 3644 is a brighter 14thmagnitude
spiral, but it's a foreground
imposter at half the distance. When I
examined SHK 352 through Jimi Lowrey's
jumbo-size 48-inch in west Texas,
four new members (numbers 5 through
8) joined the heap.
Challenges in Ursa Major
SHK 5 is better known as HCG 50 and
is considered the most difficult of the
100 Hickson groups. Locating the field
is easy - just head 20′ east-southeast of
M97, the Owl Nebula. But SHK 5's five
members are stuffed into a minuscule
40″ circle, with daunting magnitudes
ranging from 17.2 to 18.7.
The key to pinpointing the group is
an isosceles triangle formed by two 13thand
15th-magnitude stars separated by
Shakhbazian Galaxy Groups
Object
Brightest
Member
SHK 16
SHK 166
SHK 202
SHK 352
SHK 5
SHK 1
PGC 59049
PGC 59174
PGC 39737
PGC 34794
PGC 34447
PGC 32808
Mag(v)
14.6
14.9
14.6
14.6
17.2
17.2
Size
5.2′
7.8′
9.5′
2.7′
0.7′
1.2′
2.7′ east to west. A fainter 16th-magnitude
star 2′ south completes the triangle.
You'll need to spot this star easily, as the
members of SHK 5 are much dimmer.
Using my 24-inch scope at 200×, I navigated
to the field and centered the star.
I bumped the magnification up to 450×
and bingo! SHK 5-1 (HCG 50A) popped
into view just 20″ northeast of the dim
star. The subtle, very compact glow was
quite satisfying, considering the ancient
light was emitted 1.9 billion years ago!
What about SHK 1, the prototype?
Detecting any of its members requires
large optics, dark and transparent
skies, and an experienced eye. I've only
observed the cluster through Jimi's
48-inch and McDonald Observatory's
82-inch Otto Struve Telescope. However,
German amateur Uwe Glahn
sketched the four brightest members
in superb conditions using his 27-inch
reflector at 419× to 586×. To locate this
formidable target, steer 50′ west of
5th-magnitude 47 Ursae and 5′ southsouthwest
of a 10.3-magnitude star.
When I peered into the 48-inch at
375×, I noticed a faint, lumpy patch
1′ in diameter with a 15th-magnitude
star 1.5′ to its northwest. Increasing to
488×, 17.2-magnitude SHK 1-1 resolved,
along with several other gossamer spots.
The closest is 18th-magnitude SHK 1-2,
barely off its east edge. Using 813×, I was
amazed to see SHK 1 fracture into seven
teensy galaxies down to magnitude 18.5!
If you have a large telescope and
RA
16h 49.2m
16h 52.8m
12h 19.9m
11h 21.5m
11h 17.1m
10h 55.1m
Dec.
+53° 25′
+81° 38′
+28° 23′
+02° 53′
+54° 55′
+40° 27′
Angular sizes 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.
enjoy viewing galaxies in bunches, the
SHK compact groups could be your next
observing project. Alvin Huey provides
an observing guide with finder charts
and images at www.faintfuzzies.com to
help you get started.
¢ Contributing Editor STEVE GOTTLIEB
enjoys viewing galaxy groups of all sizes
from northern California. For more of his
favorite observing projects, see
adventuresindeepspace.com.
60 APRIL 2025 * SKY & TELESCOPE

http://www.faintfuzzies.com http://www.adventuresindeepspace.com

Sky & Telescope - April 2025

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