Sky & Telescope - October 2020 - 58

OCTOBER 2020 OBSERVING
Deep-Sky Wonders

7025

NGC 6956 displays a faint oval halo,
tipped a bit south of east, enveloping
the elongated form seen in the smaller
instruments. Its center harbors an oval
core aligned north-south.
Another globular cluster, NGC 7006,
ﬂoats 3.6° east of the Dolphin's nose.
It's smaller and fainter than NGC 6934,
but it's easily noticed at 37× through my
130-mm refractor, and it grows brighter
toward the center. The cluster is about
2′ across and slightly elongated eastwest. Two 14th-magnitude stars lie off
the edge, a shade west of south, but no
stars are resolved in the cluster.
Through the 15-inch reﬂector at
216×, NGC 7006 spans 3′ with a
mottled core about half as large. Faint
foreground stars graze the edge of the
cluster approximately north, northwest,
south, and east. Several extremely faint

Delights of the Celestial Dolphin
Object
Σ2735
NGC 6934
NGC 6928 (group)
Thompson 1
NGC 6956

Type

Mag(v)

Size/Sep

Double star

6.5, 7.5

2.0″

20h

Globular cluster

8.8

7.1′

20h 34.2m

Dec.

55.7m

+4° 32′
+7° 24′

Galaxy

12.2

2.2′ × 0.6′

Asterism

9.0

5.7′

20h 38.5m

+11° 20′

Galaxy

12.3

1.9′ × 1.3′

20h 43.9m

+12° 31′

20h

32.8m

+9° 56′

NGC 7006

Globular cluster

10.6

3.6′

21h

01.5m

French 1

Asterism

7.1

12.5′

21h 07.4m

+16° 18′

+16° 11′

NGC 7025

Galaxy

12.8

1.9ƍ × 1.2′

21h 07.8m

+16° 20′

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.

OCTOBER 2 02 0 * SK Y & TELESCOPE

S The photo above shows NGC 7025 hovering
near the easternmost star of French 1. Turn
the magazine 135° counterclockwise to see
why this asterism is called the Toadstool. The
sketch at left shows Finnish stargazer Jaakko
Saloranta's impression of the Toadstool at 96×
through his 8-inch telescope.

stars glimmer in the halo and some in
the outer core.
NGC 7006 is dimmer and more
difﬁcult to resolve than NGC 6934
largely because it's much farther away -
135,000 light-years compared to 51,000
light-years.
Sailing 1.4° east of NGC 7006, we
come to French 1, a 13-star asterism
of 9th- to 12th-magnitude stars. I call
it the Toadstool, because it looks like a
mushroom with its stem northeast and
the 12.5′-wide cap southwest. Washed up
against the foot of the Toadstool, we ﬁnd
a bit of celestial ﬂotsam in the form of
NGC 7025. Through my 105-mm refractor at 153×, this ashen galaxy shows
a broadly brighter, slightly oval core
encircled by a thin, faint, 45″-long halo
tipped northeast. In the 15-inch reﬂector
at 216×, it covers about 1½′ by 1′, its eastern ﬂank guarded by a 13th-magnitude
star and its western ﬂank by the golden
star at the base of the Toadstool.
For such a small constellation,
Delphinus certainly holds a wealth of
deep-sky objects. I hope some of them
will make a big splash with you.
Contributing Editor SUE FRENCH
wrote this column for the October 2009
issue of Sky & Telescope.

POSS-I / STSCI / CA LTECH / PA LO M A R OBSERVATORY

axis, and a small oval core, while UGC
11590B merely looks like a brightening
at its apex.
If you're looking for still tougher
game, download an image of the surrounding area and use it to help you
hunt down the plethora of faint galaxies
that wade in these celestial waters.
Now we'll leap up to Thompson 1,
whose three brightest stars are shown at
upper left in the chart on page 57. This
asterism was brought to my attention
by Canadian amateur John Thompson.
Through my 130-mm refractor at 63×,
it shares the ﬁeld with Iota (ι) Delphini,
which glistens 10.4′ west-northwest. I
count 13 stars, magnitude 10 to 13, in
a distinctive, 5.7′-long triangle whose
pointy end aims south-southwest.
Our next port of call is a galaxy that
exhibits interesting structure. NGC
6956 is a 1.5° voyage east-southeast
from golden Theta (θ) Delphini. In my
105-mm refractor at 47×, it's a small
hazy spot trying to hide in the glow of
the 12th-magnitude star on its eastern edge. At 127×, the galaxy appears
inclined north-northwest. My 10-inch
scope at high power adds little, other
than a faint double star just east of
the superposed one. But my 15-inch
reﬂector at 247× uncovers much more.

Sky & Telescope - October 2020

Table of Contents for the Digital Edition of Sky & Telescope - October 2020