Photos By Terence Dickinson

First on our hook is Messier 30 in southeastern Capricornus. Some 26,000 light-years away, M30 is a globular star cluster whose diameter (11 arc minutes) and visual magnitude (7.2) place it well behind the best globular clusters. But M30 is alluring in its own way, as we shall see.

The route I take to M30 is easy using the telescope's finder. I begin at 2.9-magni-tude delta (6) Capricorni, which marks the northeast corner of the constellation. Eight degrees southwest of delta is 3.8-magnitude zeta (t). At zeta, I turn sharply east for nearly four degrees until my finderscope picks up 5.2-magnitude 41 Capricorni. At that point, I insert a low-magnification (44x) eyepiece in my 10-inch Dobsonian.

A gentle push westward from 41 Cap sweeps up the expected small, round smudge of M30 together with an 8.6-magnitude "guardian star" on its western flank.

An eyepiece delivering 82x transforms the smudge into a mass that is slightly elongated east-west and strongly brighter in the middle. Increased magnification resolves some 12th-magnitude cluster members scattered across the broad core and surrounding

Fomalhaut

Iialo. Curiously, the northern half of the halo appears unusually large and jagged.

Concentrating on that area at 200x, I note two stubby "legs" of 12th- and 13th-magnitude stars radiating northward in aV-formation.Two more strands issuing from either side of the core also curl raggedly northward.

Radial chains of stars are common in globular clusters, but those of M30 all trend in one direction, giving it a lopsided, leggy look. Someone recently dubbed M30 the Jellyfish Cluster, an appropriate name, indeed.

Resolving the details that I've noted here can be challenging for Canadian observers, because M30 rides low and consequently suffers from poor "seeing" (turbulence in the Earth's atmosphere). Situated 23 degrees below the celestial equator, M30 crests as high as the Sun does on the day of the winter solstice— which is to say, not very high at all. For the best results, try for the Jellyfish Cluster when it is near its maximum height above the southern horizon. M30 will be due south around midnight in early September, by 10 p.m. in early October and by 8 p.m. in early November.The Moon will be absent in each case.

The Helix Nebula, NGC7293, represents a different kind of challenge. This large but extremely pale object is a difficult catch unless you're far from city lights. The Helix sits almost 12 degrees east-northeast of M30 in an inconspicuous region of Aquarius. To locate the nebula, I employ the Great Square of Pegasus as a celestial pointer.

When I extend the west side of the Great Square downward in the direction of first-magnitude Fomalhaut, my sight-line passes by 3.3-magnitude delta (6) Aquarii. Delta tops a seven-degree-long line of three successively fainter stars slanting toward the nebula. The second star is 4.7-magnitude 66 Aquarii, and the third is 5.2-magnitude upsilon (u).The ghostly Helix Nebula floats 1.2 degrees west of upsilon.

Estimates ofNGC7293 s distance range from 400 to 650 light-years, which is relatively close by astronomical standards, and its visual magnitude of 7.3 is bright for a planetary nebula. But because the nebula's diffuse light is spread across a fairly large area of sky (16 by 12 arc minutes)—a bit less than half the Moon's diameter—its contrast is very low.

Enter my 8-inch f/4.5 Newtonian reflector, whose wide field concentrates the pallid nebula into a small space and provides a generous "frame" of dark sky around it. At just 38x, the Helix Nebula appears in my 8-inch as an oblong wreath of nebulosity with a large central hole only slightly darker than the surrounding haze. When I increase the power, I can detect the 13th-magnitude central star but the nebula itself becomes so large that it's washed out.

A narrowband O-III nebula filter or even a basic light-pollution-reduction filter enhances the contrast between the faint Helix Nebula and the surrounding sky. Away from city lights, my O-III filter gives the nebula a patchy texture that becomes more apparent the longer I look. At other times, I have to employ the filter just to delect NGC7293. Yet when conditions are right, I've been able to spot that misty cloud in 7x50 binoculars. Don't give up on the Helix!

ASTROPHOTOGRAPHERS ' X

EdgeHD Optics! www. khanscope -com - ;

CGE pro 1100

The Celestron CGE Pro 1100 EdgeHD is an aplanatic ^fei—

Schmidt telescope designed to produce aberration-free """ ^

images across a wide visual and photographic field of view — Pi^T^ffi

• Superior edge performance not only creates rounder. /

more pleasing stars but actually improves the resolution ^^^«L ^

and limiting magnitude of instruments of similar / ' E, apertures '

The NexStar 6" & 8" instruments combine jW"T t lightweight versatility with heavyweight ' 'I

performance \ ^

• Powerful and easy-to-use SkyAlign1" Software \ ■ jf' ^ "x ™

• Includes NexRemote" Telescope Software for "4* IN advanced control of your telescope via computer SS? STOCK!

• The SKY'" Planetarium Software—with 10.000-object nexstar 6 & 8 se database, printable sky maps and enhanced images

Was this article helpful?

0 0
Telescopes Mastery

Telescopes Mastery

Through this ebook, you are going to learn what you will need to know all about the telescopes that can provide a fun and rewarding hobby for you and your family!

Get My Free Ebook


Post a comment