wants to see the famous Horsehead in Orion, but few beginners realize
just how difficult an object it is. It is important to consider
that this object's fame came about in long exposure photographs which
show much more than you can see visually. To see the Horsehead
for the first time you will need to be fully dark adapted, have clear,
dark skies, and a large aperture instrument (probably something on the
order of a 16"). A narrow band filter such as an H-Beta or
UHC filter can really help, and may make it visible in smaller scopes.
Having someone who has seen it coach you can also be a great help.
one of those objects that gets easier once you learn to see it.
As usual, knowing what to look for is the key. Eventually you
will be able to find it in smaller instruments or without a filter.
to start is the Flame Nebula (NGC 2024) which lies just to the
northeast of Alnitak, the easternmost star in Orion's belt. If
you can't see this nebulosity there is no point in looking for the
much more difficult Horsehead. In fact, you need to be able to
clearly see the dark lane that crosses this nebula if you are going to
have any chance at all. Spend some time here trying to see as
much detail as possible--it's great practice.
also want to try and see NGC 2023, the nebulosity surrounding HD
37903. This 7.8 magnitude star lies to the southeast of Alnitak
and is pretty much on the way to the famous Horsehead. NGC 2023
isn't all that difficult, except that it has a relatively bright star
within it. Some people (myself included) seem to have more
difficulty making out nebulosity that surrounds a relatively bright
star. In any case, seeing the NGC 2023 nebula may be a good
confidence builder as you move to the main event. Look for a faint,
oval haze surrounding the star.
stop should be HD 37805, a 7.5 magnitude star that lies about 8' to
the southwest of HD 37903. The Horsehead nebulosity passes
pretty much north-south just to the west of this star. Look for
a faint, elongated skyglow. This area of the sky should look
ever so slightly brighter than the surroundings. An H-Beta
filter can really bring it out. Don't be afraid to use high
magnification to increase the contrast, particularly if you aren't
using a filter. But you also don't want to use so much that the
nebula fills most of your field of view. This can also make it
hard to detect against the background. You may want to place HD
37805 out of the field, if possible.
that you are comfortable and spend a lot of time looking. A
quick look just won't do--you have to relax and work at it. You
should be sitting down, if possible. It can help if you can keep
both eyes open as you look. If there are any stray lights in the
area, sometimes placing a cloth or towel over your head at the
eyepiece can make all the difference.
are confident that you can see the feeble glow of the nebula, look for
a notch or hole about 8' due south of HD 37805. Use averted
vision. If you can convince yourself that you have seen a notch,
then you can claim success! With practice over time, and on one
of those rare excellent nights, you may see this notch well enough to
make out the familiar Horsehead shape. As always with difficult
objects, the best chance for success is to keep looking over and over
again. You may be surprised how much more you can see if you
just keep at it!
This is the
view in a 12-inch LX200 at 76x. The red areas are where you should
look for faint nebulosity. The field of view (circle) is 51'.
North is down and east is to the right.
faint nebula is IC 434, but it is the intrusion of the nearby B33 dark
nebula complex that creates the famous silhouette of the horses head.
B33 is actually a much larger complex of obscuring dust, stretching
several degrees, most of which is found to the east of the IC 434
Horsehead with a filter is a real accomplishment; finding it without
one is something to very be proud of!