Sky & Telescope - January 2025 - 57

DSS2 (2)
pSTELLAR CLUSTERS Left: The side-by-side clusters NGC 1807 (right) and 1817 (left) are loose collections of mostly dim stars. However, each one
features a colorful mixture of blue-white and yellow-white suns, with a distinctly orange star lying near the south edge of NGC 1817. The blue star at
the north end is a binary named HJ 3269. It consists of 8.7- and 10.8-magnitude components 20.0″ apart. Right: The cluster identified as NGC 1746
is likely two clusters located at different distances. The western portion is designated NGC 1750, while the eastern section is called NGC 1758.
and 6th-magnitude stars. From south
to north, the Flamsteed four are 104,
106, 105, and 103 Tauri (I almost got
drawn off-course by 4.6-magnitude Iota
Tauri, 1° west of 105 Tauri). Finally, a
gentle nudge of the Dob 1° west-southwestward
from 103 Tauri grabbed NGC
1746, a cluster that easily outclassed the
previously observed ugly ducklings.
NGC 1746 weighs in at magnitude
6.1 and is about 40′ across. The 8-inch
Newtonian captured upwards of five
dozen blue-white stars, all except one
under magnitude 8.5. The coarse bunch
includes AG 313, a delicate duo southwest
of center. Its 9.4- and 10.0-magnitude
components are 19.8″ apart. In
addition, NGC 1746 is bordered along
its eastern side by a sharply bent fence
of five 7th- and 8th-magnitude orange
stars. Bumping up to 135×, then concentrating
on where the fence bends, I
glimpsed a 10′-wide clump of at least 20
exceedingly faint pinpoints. This pallid
bunch is possibly an unrelated cluster
far beyond NGC 1746.
Shifting the telescope 6¼° southwestward
toward Aldebaran swept up
6.4-magnitude NGC 1647 (it's 3½°
northeast of Aldebaran). The finderscope
couldn't detect the cluster but it
netted two neighbors just to its south
- 6.0- and 7.5-magnitude yelloworange
stars, 5′ apart, oriented southeast-northwest.
Together they act as a
signpost for the thin glitter lying ¼°
northward. Working at 41× again, the
8-inch corralled perhaps 60 stars, all
below magnitude 8.0, covering 40′ of
sky. The jewel in the NGC 1647 crown
is AG 311, a quickly spotted double
consisting of 8.9- and 9.3-magnitude
stars separated by 33″.
From NGC 1647, I headed home to
Aldebaran. Jupiter, beaming at magnitude
-2.6, adds luster to the scene as it
plies a retrograde course slowly westward,
just north of our modest targets.
Brave the January chill and go get 'em!
¢Contributing Editor KEN HEWITTWHITE
is a seasoned connoisseur of
clusters, bright and dim.
Treasures in Eastern Taurus
Object
Aldebaran
NGC 1807
NGC 1817
Cr 65
S 478
Σ730
H 3275
Σ697
NGC 1746
AG 313
NGC 1647
AG 311
Type
Star
Open cluster
Open cluster
Open cluster
Double star
Double star
Double star
Double star
Open cluster
Double star
Open cluster
Double star
Mag(v)
7.0
7.7
-
12.0′
20.0′
220′
Size/Sep
RA
5.1, 8.8
6.1, 6.4
7.7, 8.2
7.3, 8.1
6.1
9.4, 10.0
6.4
8.9, 9.3
+0.9 - 4h 35m
5h 10.8m
5h 12.5m
5h 26.1m
5h 24.4m
5h 32.2m
5h 29.8m
5h 23.5m
5h 03.8m
5h 03.6m
4h 45.7m
4h 45.9m
106.7″
9.7″
56.1″
25.4″
40.0′
19.8″
40.0′
33.0″
Dec.
+16° 31′
+16° 31′
+16° 41′
+15° 42′
+17° 23′
+17° 03′
+18° 25′
+16° 02′
+23° 46′
+23° 39′
+19° 07′
+19° 11′
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 * JANUARY 2025 57

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Sky & Telescope - January 2025

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