The following post updates an earlier one in this series; it was also published in Aurora, the newsletter of the Windsor Branch of the Royal Astronomical Society of Canada.
In earlier posts I talked about
astronomers who work their way methodically through object lists,
often to the detriment of the object. A quick glance, a note or two,
maybe a quick sketch and then they are off to the next object. All
well and fine if you are looking at 14th magnitude galaxies, but if
your list is packed with the brightest deep sky gems, what is the
hurry? 400 top objects could well last your entire life.
To make certain that I never finish my life
list, or run out of options on any given clear night, I chose the NGC
list a long time ago as my main deep sky emphasis. I will not pass a
Collinder or Berkeley cluster without a look, but my longest viewing
time is spent on the NGC list. In a lifetime of observing I have seen
and logged many of them. Ones seen
previously with the 8” scope are being reviewed with the 12”.
And some of the best ones are being glimpsed with my 2”
refractor. It’s fun to compare the notes of past
viewed objects when using a different scope.
The current edition of
Uranometria 2000 claims that more than 30,000 non-stellar objects are
on its charts. That's over 22,000 more than are in the NGC list. Good
grief. Makes me kind of thankful that I am not overly obsessed. Of
those 30,000 objects, nearly 26,000 of them are galaxies. Which means
that nearly 5 in 6 non-stellar objects viewable in the night sky with
amateur scopes are galaxies. Most of those are pretty faint, too.
Here is the breakdown, as reported on the atlas' back cover,
remembering that this encompasses the north and south skies:
25,883 galaxies
671 galaxy clusters
(Abell)
14 star clouds
1,613 open
clusters, including those in the Magellanic Clouds
170 globular
clusters
355 bright nebulae
367 dark nebulae
1,145 planetary
nebulae
260 radio sources
35 x-ray sources
I remember being very surprised when I first
learned how many galaxies were available to amateur astronomers (all
the ones listed in Uranometria are mag. 15 or brighter). I mean that
I was very surprised. Growing up loving the
Milky Way area and all of its clusters and nebulae, it was easy to
conclude that clusters of stars far outnumber galaxies. That, to say
the least, was an erroneous conclusion. If one decides to choose the
NGC for a life list, one must be prepared to see some galaxies. I
don't just mean the ones in the Messier catalog, either.
Finding and doing justice to galaxies requires
the very darkest of dark skies. I used to be able to
pick off 12th mag. galaxies from my back deck in Anderdon
with my 8" scope. Light pollution has increased so much in my
area that this is now almost impossible, even
with a 12”. If I want to do a decent job of
observing in Sextans this spring, I have to be prepared
to travel with the scope. This brings on an interesting conundrum. Do
I observe the brighter galaxies from my home, saving the fainter ones
for country skies? Though this is a feasible plan, I try to imagine
what brighter objects might look like from a dark sky.
If I can even glimpse it from home, then it should
be that much more impressive from a dark sky. Should I save all my
faint objects for darker skies? What about the Messier
list? What would these objects look like from a
really dark sky site, if only seen from light polluted ones?
One way to help tackle
this problem, which I'm certain many of us face all too often,
is to keep notes and report on the brighter ones as seen from home
suburban skies, but also return to them in dark skies and enjoy
another, more lingering look. Open clusters and
globulars that resolve, for example, will show many
more stars from a dark sky, and galaxies can be expected to show a
larger area and appear brighter, especially towards the center.
Light pollution filters work extremely well in light polluted
skies. However, their future under LED lights remains in flux.
Double star work can carry on quite
well, too, from poorer skies, often even during full
moon nights, though the rich background seen in a dark sky
might reveal a hidden gem or two to the very observant viewer that
would be otherwise unnoticed. However, I
am determined to do as much deep sky work in the darkest skies I can
reach, though I realize that time is running out for the
Windsor area. I've been spoiled by my northern Ontario early
years of observing, and even by Hallam when it was at its
best.
Messier Of The Month: M 43
M43 is also
commonly known as De Mairan’s Nebula, as well as NGC 1982. De
Mairan was a French scientist who lived from 1678-1771. He observed
the nebula in 1731, which Messier later added to his now famous list.
The sword area of Orion, which also includes the more famous and
much larger M 42, contains no less than 10 separate NGC numbers, and
makes for a fascinating hour of observing to tell one from the other.
This area shall be the subject of a future At The Eyepiece article.
M43 is not only
overshadowed by its bigger deep sky mate M 42, it is actually a part
of it. M 43 lies just barely north of M 42, separated from it by a
narrow dark lane, and is almost touching the main nebula. Look for
an ivory coloured 7th magnitude star north of the big
nebula. M 43 encircles this star, with more of it showing south of
the star than north. A fainter elongated segment lies north again,
towards another star. The nebula is easy to see without a filter,
and should be visible in scopes of 4”. Although noted in years
past with the 4.5” Tasco reflector, the above description was made
using the 12” Orion Dobsonian, from Hallam, on January 5th,
2019. Next time you are observing in this area, make sure to take a
look at Messier 43. An interesting article could also be written
about Messier objects that can be viewed with other Messier objects
in the same field of view. This is one of them.
Messier 43 (NGC
1982): 20’ x 15’; Emission and Reflection Nebula.
Clear skies, and happy observing.
Mapman Mike
