Australian Sky & Telescope - June 2018

52 AUSTRALIAN SKY & TELESCOPE July 2018

TARGETS by Sue French

(atmospheric steadiness) and very high

magnification.

Although M57 looks like a simple

ring, its structure is actually much

more complicated. You could think of it

as a bright doughnut wrapped around

the middle of a faint AFL football, all

embedded in a complex, tenuous halo.

The ring structure dominates largely

because we’re gazing down the pole of

the planetary nebula. If we could see

the Ring Nebula from the plane of its

equator, it might look much like our

next object, the Dumbbell Nebula

(M27) in Vulpecula, the Little Fox.

Swept up by Charles Messier in 1764,

M27 was the first planetary nebula ever

discovered. It rests 24′ south-southeast

of 14 Vulpeculae and can be recognised

through my 9×50 finder. When seen

through my 130-mm scope at 23×, the

Dumbbell Nebula looks substantially

larger than the Ring Nebula. Its bright

region is shaped like an apple with

the sides munched away. Protruding

from the sides of this apple core is a

dimmer region that turns the nebula

into a football. At 48× the apple core’s

rims shine brightest, and its pinched-in

sides are more obvious. There’s also a

fairly bright bar diagonally connecting

the caps from east-northeast to west-

southwest. The football extensions

stand out best at 63×, but it’s a rather

plump football. Upping the power to

164 × the apple core displays brighter

wedges hugging the narrower angles

where the bar meets each cap. At 234×,

the southwestern wedge seems brighter

than its counterpart in the northeast.

The Dumbbell’s central star is

easier to spot than the Ring’s, but it’s

still not easy. The smallest scope I’ve

seen it through was my husband’s

erstwhile 140-mm refactor, employing a

magnification of 300×.

Next we’ll visit the gorgeous Lagoon

Nebula (M8), named for the darkling

STheauthor’ssketchofM57,theRingNebula,

as seen through her 130-mm refractor at 234×,

shows the nebula’s gauzy, circular interior.

Ring Nebula

Sue’s winter favourites

Object Type Mag(v) Size/Sep RA Dec.

Ring Nebula (M57) Planetary nebula 8.8 1.6′ × 1.1′ 18 h 53.6m +33° 02 ′

Dumbbell Nebula (M27) Planetary nebula 7.4 8.0′ × 5. 5 ′ 19 h 59.6m +22° 43 ′

Lagoon Nebula (M8) Emission nebula 3.0 45 ′ × 3 0 ′ 18 h 04.1m –24° 18 ′

Omega Nebula (M17) Emission nebula 5.5 20 ′ × 1 5 ′ 18 h 20.8m –16° 10 ′

Butterfly Cluster (M6) Open cluster 4.2 33 ′ 17 h 40.3m –32° 16 ′

Angular sizes and separations are from recent catalogues. Visually, an object’s size is often smaller than the catalogued value and varies according to the aperture

and magniication of the viewing instrument. Right ascension and declination are for equinox 2000.0.

SUE FRENCH (4)

STheauthorsketchedtheLagoonNebulaas

viewed through her 130-mm refractor at 48×.

SSometimes called the Swan Nebula due

to its evocative shape, the Omega Nebula

improveswhenviewedthroughanOIIIor

narrowband ilter. The sketch shows the view

througha130-mmrefractorat63×.

SThe Butterly Cluster really sparkles with

binoculars or a small scope. The sketch shows

the individual lights as viewed through a

130-mm refractor at just 48×.

9 Sgr

BM Sco

7 Sgr

NGC 6530

Lagoon Nebula

Omega Nebula Butterfly Cluster