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Home / Small Wonders: Delphinus and Equuleus
by Tom Trusock 08/19/04 | Email Author  Voice your opinion about this topic in the forums
Small Wonders: Del and Equ
Small Wonders:
Delphinus and Equuleus
A
Monthly Beginners Guide to the Night Sky
by Tom Trusock
A printable version can be found
here.
Wide field
Chart
Target
List
|
Name
Type
Size
Mag
RA
DEC
1
Equulei
Multiple
5.3 20h 59m
19.1s +04° 18' 40"
gamma Delphini
Multiple
4.3 20h 46m
53.1s +16° 08' 27"
gamma Equulei
Multiple
4.7 21h 10m 34.7s
+10° 09' 00"
NGC 6905
Planetary
Nebula
1.2' 11.1
20h 22m 36.1s +20° 07' 12"
NGC 6934
Globular
Cluster
7.1'
8.9 20h 34m
25.9s +07° 25' 14"
French 1
Asterism
21h 08m
01.1s +16° 21' 16"
STF
2703
Multiple
8.3 20h 37m 03.1s +14°
44' 41"
STF 2742
Multiple
6.7 21h 02m 26.8s +07°
11' 50" |
Challenge
Object
|
Name
Type
Size
Mag
RA
DEC
NGC
7006 Globular
Cluster
3.6'
10.6 21h 01m 43.2s
+16° 12' 22" |
A SkyMap Pro Target List for these
objects is available.
Note: the toadstool uses galaxy NGC7025 to mark it's base.
Dolphins and
Practical Jokes
This is something of a sparse piece of sky if you are only interested
in looking for bright showpiece objects. For small scopes, there
are a few nice deep sky targets in Delphinus, but little in
Equuleus. In fact, for small scopes, the only thing that Equuleus
really has to offer is some nice multiple stars. But, taking a
page from Walter Scott Houston - there's something to be found
even in the most barren area of the sky.
 While
there are at least three stories as to how Delphinus ( the
Dolphin) wound up in the night sky, there's something you might find a
little more interesting about this constellation - something that
revolves around a young man we'll call Nick Hunter. Something
that was more than likely a practical joke - and a rather stellar one
at that.
Do you know Nick Hunter?
Sometimes there's more than
meets the eye in the stars. Take Alpha and Beta Delphinus for
example.
Sualocin and Rotanev.
Odd names to say the least.
They first appeared in the Palermo Catalog of 1814, and for many long
years were a mystery.
It was English astronomer Thomas Webb who finally solved the
puzzle. He noticed that if you wrote them backwards, you
came up with Nicolaus Venator - the
Latinized form of Niccolo Cacciatore, the assistant and later successor
(1817) of the Italian astronomer Guiseppe Piazzi at Palermo
Observatory. Niccolo Cacciatore (in english - you guessed it -
Nick Hunter) is the only person who has ever successfully named not
one, but two stars after himself!
As you gaze at the Dolphin and its delights tonight, take a moment to
share a laugh with Nick Hunter. I've oft found it ironic that
Cacciatore picked the Dolphin for his joke - after all, Dolphins are
supposed to have something of a sense of humor.
A double and a triple in Delphinus
We'll start with a pair of
multiple stars that are easily found in in the main body of the
Dolphin. First head out to Gamma Del in the tip of the dolphins
nose. In the TV102, I see
two golden hued stars at low power with the one to the northern side
slightly dimmer. It's an easy split at 36x, and is even possible
at 22x, but increase the power, and you are in for a treat - one of the
components becomes an obvious blue green while the other remains gold.
Next head diagonally down to the opposite side of the body of the
dolphin. Just to the NW of Beta lies STF2703.
An easy catch, it's split easily at 36x, but higher
powers frame the barely obtuse triangle a little better. Look for
the colors - two reddish stars, and one with a blue white tinge.
Fair warning: For the rest of the objects this month, you're going to
have to work a little harder.
NGC 6934 - Globular Clusters Ahoy!
 For the remainder of
the targets this evening, you are going to have to do some very simple
star hopping. 
For our first target, we will head down the dolphins tail, and then go
about another tail length directly south.
Once you get to this area, start scanning the area at low powers for
globular cluster NGC 6394.
This is a cotton ball with no resolution in the 85mm and
102mm scopes, but still fairly bright and large. A 15" at 170x
brings a wealth of
fine detail and resolves stars across the outer
fringes, while 313x begins to resolves stars towards the center.
In fact, the view through the 15" reminds me of how M13 appears in a
good 4" scope on a a decent evening.
NGC 6905 - The Blue Flash
 
Lets go for lesson
#2 in star hopping - NGC 6905. Now, mentally, connect delta and
alpha
delphinus as shown in the chart above, and head out about 5 of the
"delta/alpha lengths". Once you are in the area, check through a
low power or finder view against the pictures shown above and see if
you can identify the field. It might take a little fishing
around, but don't give up. Remember that depending on the
equipment you are using, the view might be reversed right to left,
inverted top to bottom both or neither!
Discovered in 1782 by William Herschel, this planetary is surprisingly
accessible even to small scopes. On a good dark night, I've caught this
in an 85mm scope and it's nothing to write home about, but you can tell
there's something
there. Usually, from my site fairly dark site, it takes a 4" or
larger scope to pull this one
out, and it's pretty faint at that. Larger scopes turn it from a faint
wisp into spectacular site: In the 15", it clearly shows
structure similar to the
photos above - a ragged oval embedded in one side of a trapezium.
It's a real showpiece with some aperture and dark skies.
Look for a faint
haze in a fairly recognizable grouping
of stars as shown in these images - three of the keystone stars are
recognizable in a 4" scope. Be sure to use averted
vision.
Gary Gibbs has
viewed it in his 10" SCT
and Collins I3 from a light polluted site, and notes"...it was very
hard to see. Same goes for visual. I did see it with the I3 using
averted vision..." As you can see by the smaller picture - Gary
had more success with imaging.
If you are viewing 6905 with a larger scope, try upping the power -
regardless of what the seeing conditions seem to be. I usually
find my best views of planetary nebulas to be around 400-500x in my 15"
(or even higher). Planetaries are one of those targets it's ok to
"bend" the sane magnification rules.
This is also a good time to break out the UHC or OIII filters as
planetaries typically respond fairly well to these sophisticated tools.
French 1 (The Toadstool)
 For this
one, mentally draw a line between gamma and alpha del, and extend that
line about 2.5 times from the body of the dolphin and just a little
south to hit French 1 - Sue French's ToadStool. This is a very
nice probable asterism located on the far eastern side of Delphinus.
(B. Alessi independently discovered this grouping, and notes that the
proper motions of the brightest stars are somewhat similar, so it may
in fact be an actual cluster - Star Clusters: Archinal and
Hynes).
While French notes that it's best viewed at moderate powers, I found it
to be nicely framed and easily picked out at low powers (22x) in a 4"
scope. I saw 10 - 11
stars in a fairly obvious toadstool shape with the cap of the shroom
pointing to the South, and I found the best views were in a 30mm
wide field that yielded 27x and around a three degree true field of
view. The galaxy at the base of the celestial mushroom is NGC
7025 - listed at map 12.9, and a size of 1.9' x 1.2' - what's the
smallest scope you can spot 7025 in?
I thought this was the one of the better objects in the area, easily
visible in a small scope. And while it seems a little dim and
small, I have to wonder - Has anyone managed to pick it out in
binoculars?
Doubles in the Colt
Since it's brightest and only named star (Kitalpha) shines at a
somewhat paltry magnitude 3.97, Equuleus can be a difficult
constellation to find, let alone star hop in. You might want to
scan this area in a pair of binoculars to see if you can get a good
idea of where the four brightest stars are located and familiarize
yourself with the area. I've found an optical finder is a great
help in getting around areas like this..
But even so, there are at least three worthy doubles for a small scope
in this seemingly barren area.
Gamma Equulei: A wide and bright double, use low powers -an
incredibly easy split at 22x in a 4" scope - this star probably can be
split with binoculars, but I haven't tried it. Give it a shot,
and let me know.
STF 2742: First observed by F.G.W Struve in 1831, This is a much
closer double than our first stop. At
36x, it's a straight line with no separation visible. At 200x, it
looks like eyes staring at me out of the dark of space.
1 Equulei (STF 2737) - Two golden hued stars in my 4" scope, one much
brighter than the other I found my best views at 200X.
Challenge Object: NGC 7006
 It's
almost not fair to give a challenge object this month. If you
have made it this far, you've already hit targets harder than in any of
my other columns. HOWEVER... this is a rather interesting target
and well worth a stop if you can find it. At a distance of 185000
light years, NGC 7006 is one of the farthest globulars known to be
associated with our galaxy.
In a 4" scope, this is a difficult target to say the least. On a
superb night, I found that at 36x I
could hold it with direct vision only about 70 percent of the
time. In
a 15" scope, my notes say that I picked up a few stars across the face
at higher powers.
Additional Reading:
For a twist, I thought I'd recommend a few
resources that don't require electricity this month:
Deep Sky Wonders - Walter Scott Houston: This is a
classic written by one of the most prominent deep sky observers of our
time. Scotty was a long time observing columnist for Sky and
Telescope, and this book is the distillation of his columns
Observing Handbook and Catalog
of Deep Sky Objects - Christian
B. Luginbhul and Brian A. Skiff: A compilation of observations
with scopes from 60mm to 12", this is an incredibly helpful tool to
have when planning your own starhops.
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