Australian Sky & Telescope - 02.2019 - 03.2019

56 AUSTRALIAN SKY & TELESCOPE February | March 2019

GOING DEEP by Howard Banich

MASIL IMAGING TEAM

Fleming’s

semicircular indentation

Can you see the Horsehead Nebula? It’s all about contrast and scale.

I

got pretty excited the first time I saw the Horsehead Nebula.

Here are my notes from the early morning of October

13, 1991, which was also the first night I had my then-

new 50-cm f/5 Obsession Dobsonian under a dark and

transparent sky.

! Horsehead —

... I carefully pinpointed its exact location with Uranometria
and at 53× centred the field in the eyepiece. Then with the
16-mm at 182× and the O III filter I looked — nothing. Rats.
Let’s try the UHC — I looked — wait a minute, wait a minute —
a little more averted vision, then after all these 23 years I saw it
with my own eyes...
It was quite a bit larger (and fainter) than I expected (which is
what most people say, I hear). It was more like a darker notch
taken out of the sky rather than a silhouette against a bright
nebula. Although that may sound rather contradictory, that was
my impression. After looking at it in Chuck Dethloff’s 24-inch
and an h-beta filter (which showed it very clearly) he loaned
me the filter (which was a 2-inch) and I tried it on my 55-mm
Plossl at 53× — wow! Very obvious now with the filter and the
wider field of view.
This was the most satisfying view of anything I’ve ever looked
at. This was magical.

I was with a small group of observers at this dark sky site,

which later became the base for a regular star party. The

entire night was astounding, but seeing the Horsehead for the

first time positively blew me away.

Little did I know I didn’t need a 50-cm telescope to see

the Horsehead Nebula, and that I could have seen it with my

20-cm scope decades earlier if I’d been under a good enough

sky. But as a kid I didn’t even know it was possible to see the

Horsehead visually.

Today it’s one of the most famous deep sky objects and

after M42 probably the second most sought-after object in

Orion. However, the Horsehead is nearly impossible to see

from even mildly light-polluted skies, frustrating far too

many observers for far too long. But it’s surprisingly easy to

see under truly dark and transparent conditions — and with a

smaller telescope than you may imagine.

SICONIC NEBULA The Horsehead Nebula is silhouetted against the

brightest part of the emission nebula IC 434, which stretches horizontally

(south) through the centre of the photo from the bright star Alnitak (Zeta

Orionis, left centre), the easternmost star of Orion’s Belt. The naked-eye

star Sigma Orionis is just out of view at top. The Flame Nebula, NGC 2024,

is east of (below) Alnitak, and the much smaller NGC 2023 is due south

(right) of the Flame and northeast (below and left) of the Horsehead.

NE