Expert: Tom Whiting - 11/15/2004

Question
Hey!

... So I bought a nice 200mm apeture telescope(Celestron C8-N), and based off of my research, I should be able to see Deep Sky Objects with a fair amount of sharpness and detail (in other words, not a blur). However, I've discovered a little problem in actually finding those objects (M15, M3, M51, etc...), and I think it's a problem either with my polar alignment, RA/Dec, my star charts, or all three.
  Before I take my scope out, I print out a sky chart with the RA/Dec locations of DSO's along with the nearest visible stars to them, and for the planned time I'd be searching for them. I'm a little confused with RA/Dec because even though the stars move throughout the night, like the sun during the day, the RA/Dec stays the same...? Doesn't make sense, shouldn't they change in relation to the objects' apparent motion across the sky?
  Any ways, I've got my charts with coordinates, I set up the telescope, align the polar axis to Polaris (that's how to do Polar Alignment, right?), and I get the scope pointing towards Vega to set my RA/Dec settings. This is where I get really confused... The setting circles on my scope are sooo small, with very limited detail, that I can't possibly get the accurate coordinate of 18h 36m (I can get on 18, and try to go as close as possible to what I believe is 36, since they read like the dials of a clock). And Dec is even more confusing! I set the Dec to 38 degrees (again as close as possible, very little detail on the dial) but the Dec circles go from zero to 90, and then back down to zero, and back up to 90 and it does that about three times around the whole circle! How would I know a positive Dec from a negative? What if in my searching I cross the 0 or 90, wouldn't it throw off all of my coordinates. No indications what-so-ever.
 Any ways, I've got my coordinates as close as possible to those of Vega, so I decide to view M57, which isn't far from Vega. I move the scope in RA/Dec until they match M57's coordinates. Nowhere near the M57. Infact, Vega is still visible in my scope. Is this something where I would just guess, that is, find a star close to the object, and try to move the scope to where I believe the object is at? Should I not even worry about RA/Dec? Why do they read like a ruler (a number, say 10, followed by some dashes, then another number, say 20) when it's obvious I need more precise settings to find these DSO's.... This is a long question, but thank you very much for any insights you could provide me.

John-Mikael

Answer
Hi John,
Ok, everyone that's been in astronomy for a while knows that
those RA and DECL setting circles on C-8' s and other scopes of that size, are mainly there for looks,  and are not very useable for "dialing in" anything.
But after you calibrated it on Vega at 18 hr 35 min RA, and
+39 degrees Decl., you should be able to move the scope
to 18 Hr 54 min RA, and +33 degrees Decl. and be pretty close
to M-57 (Ring Nebula)....if not, something is wrong; either you haven't locked down the RA circle, or the Decl circle is not rotating with the scope....I don't know which, and besides, there is an easier way. You are correct- there is a much better, easier, quicker sure-fire  way!   Us who have been in amateur astronomy for a number of years, NEVER use setting circles....we find it's  much easier just to learn (memorize; self-teach yourself) the constellations and star-hop from there...it's far easier on the nervous system and eyes to do it that way, and believe it or not, it's much, much faster and actually more easy once you do it a while (and actually more fun too).....I can even beat out those computer driven scopes 95% of the time....while they are slewing, I'm near, then on the object before their RA motor quits running.

(Using method below, you don't even have to polar
align your scope, in fact, it's better if you work in the
alt-azimuth mode, so throw away that equatorial wedge,
and just set up in Altitude-Azimuth mode...its quicker-your
RA knob becomes the Azimuth, and your DECL knob
becomes your altitude control).

Notice that the constellation Lyra is the two stars above Vega  which form an equilaterial triangle Epsilon and Zeta on your star chart), and an attached parallogram toward the south-southeast....the entire constellation is about the length of a cigarette held at arm's length....now those two bright stars out on the southern end of the parallogram, the Ring Nebula is almost directly between those two stars (Beta and Gamma Lyrae on your star chart), so just grab the friggin'  scope, set the cross hairs of your 6 x 30 finderscope (or the center circle of your Telrad), directly mid-point between those two stars, lock it down, and look for the little white, powder-sugared doughnut in the primary eyepiece...the ring Nebula!
It's there, not very big, mind you...its the smallest of the
Messier objects at only about 60 arc-seconds so at low
power, don't expect something huge....just a little bigger than
a stellar image and not very bright using an 8 inch....it will
look like an out-of-focus star initially, until you realize that
all the other stars in the FOV are in perfect focus;
remember, you don't have the preferred Deep Sky Scope with
that 30% central obstruction....you bought convenience and
portability, not a true Deep Sky Object Scope....you bought
a compromise instrument....I mean they are nice for portability;
I still have my original orange Pumpkin tube C-8 from 1974.....
but I accept the compromise with that instrument.
The Ring Nebula is not quite centered between those 2 guide
stars, but you'll be close enough that you can scan around
that area, and you'll quickly run into it, if you remember that
it's just a little south and east of the mid-point of those two
stars, Beta and Gamma Lyrae.  Remember to scan s-l-o-w-l-y...
Use your lowest power (maximize field of view -FOV), then
once you find it, you can change to a higher powered
eyepiece.  This is the very best way to do it, believe me.....
forget the setting circles, learn you constellations, then learn
how to star hop, in other words, how much to offset your scope from a particular naked-eye star to find the object you want to observe.....learning the constellations is not that hard
as they are just area's of the sky, just like states.  If you can
learn and memorize PA, OHIO, IND, ILLINOIS, 4 adjoining areas,, then you can also self-learn and memorize Gemini, Cancer, Leo, Virgo. (Again, 4 adjoining areas of sky).
They are all just area's for identification purposes...you can't
find the Armory in Columbus Ohio until you first know where
Ohio is (constellation), then the city of Columbus (a guide
star or two), then offset 10 miles to the south to find the
armory....offset one or two degrees to the south to find your
Deep sky Object....this ain't rocket science...it's exactly the same process!  It's glorified bird-watching, except our "birds"
don't move, relative to the rest of the birds!  They are always
there.

Then, do you want positive control over exactly where your
scope is pointing? Spend the 40 bucks or so on a Reflex
Telrad, and put it on your scope...to be honest, those little
6 x 30 finders are almost worthless for most observing......
In fact, I use 2 Telrads on my 30 inch portable, AND a
9 x 60 Meade finderscope so I can actually see those fuzzy
Messier objects in the optical finderscope, or if I'm going after something  really faint....not visible in the 9 x 60, then I have two telrads which I can point to the exact position of say, Stephan's quintet in Pegasus at 15th magnitude as I know almost exactly where it is in the night sky....you have to know all this first.  And this is why you don't get a scope right away;
You have to first learn the naked eye night sky for 4-6 months (how long did it take to learn the States of the USA?)
and also join up with others....before buying a scope,
what do you want to specialize in.....Deep Sky Objects, variable stars, lunar/planetary detail, splitting double/multiple
stars, comet Hunt, asteroids, etc etc....there is a scope out
there that maximizes your particular speciality.....Scopes are
like airplanes; all airplanes fly, but you don't send a bomber
to do a fighter's job...scopes are exactly the same way....
otherwise, we'd all own the exact same type of scope, wouldn't we?  But we don't.  

But since you already have a descent scope, its now a good
incentive to learn the night sky....you'll be miles ahead of
all those that have coding elements and clock drives....I've
seen those people take an hour to set up, find their computer
system isn't working or their battery failed, or something happened, and they were out of luck, under a beautiful
clear, dark sky, so they had to quit.  If they had taken the
time to learn the night sky...even just a little of it....they could
have kept observing manually, like the rest of us do it all
the time.  I am my own GOTO, and my own drive....I'm not
lazy, and sounds like neither are you.

Once you learn most of the constellations, you quickly learn
that the globular M-13 is 1/3 the way on the western side
of the Hercules Keystone; the Dumbbell Nebula (M-27)
is exactly 3 degrees north of the eastern tip star (Gamma
Sagittae) in Sagitta.  The Ghost of Jupiter (planetary nebula
NGC 3242) is exactly 2 degrees south of the star Mu
Hydrae in Hydra......Globular M-56 in Lyra is almost exactly
halfway between Gamma Lyrae and Albireo, tail end of the
Northern Cross (Cygnus)....which, BTW, is the prettiest
double in the N. Hemisphere...Albireo (Beta Cygni) is.....
and you'll be on your way.
Hope all this helps....
let me know how you do, I'm at
bwhiting@velocity.net

Clear Skies,
and happy hunting, after all, part of the fun is in the hunting
and seeking,
Tom Whiting
Erie, PA

Please visit our club website for great picts of the new
30 inch DOB portable truss scope, largest in Pennsylvania
(I believe)
http://www.velocity.net/~bwhiting/





FOLLOW UP:
Oh, BTW, an 8 is fine over a 6, but not by much, relative
to DSO's....many Messier objects will still just be a bigger
blur....you have to get up into the range of a 12 or 13 inch
mirror before you can really start resolving the globulars
and planetary nebulae to their cores....but since you already
have an 8 incher, start with it....the knowledge you gain will
be super-useful later, and you'll be more appreciative of what
a 12 or 14 inch truss DOB will do for you later down the road.
But an 8 inch will do a nice job on open clusters....actually a
bigger scope doesn't do much more for the Open Clusters...
they all look pretty much the same.