Expert: Tom Whiting - 6/14/2004

Question
Hi!

Just one more small question... Is it worth it upgrading to a 8 inch in a light polluted sky?

Thank you!


-------------------------
Followup To
Question -
Hi!

I own a 4.5 inch reflector telescope and have been looking at the sky "manually" for a few months.

But I was tired of always looking at the planets, the moon, etc. so I decided to look at the deep sky objects. However, since most of the DSO are not naked-eye, I was going to need the right ascension and the declination on my telescope (german equatorial mount).

So I then decided to try polar aligning and then use the RA/Dec coordinates to find objects. I was sucessfully able to polar align my telescope. However, I couldn't locate any objects because of one reason... I didn't know which way to use the RA/Dec quadrants (clockwise or counter-clockwise).

That is my question. Once you have polar aligned the telescope/mount, how do you use the RA and Dec hours/degrees to find objects in the sky?

Thank you very much!

P.S. And what do you have to do so your telescope doesn't hit the mount while you're rotating it?
Answer -
Deeb,
Small scopes, even my old Celestron 8 came with RA and Decl.
circles...but they put them on those scopes mainly for
looks and not actual useage; they are so small and difficult
to use, I would highly recommend you do it the way almost
all of us amateurs do it, and that is to learn to star-hop
to the DSO's off a known naked-eye star or stars. It really
isn't that hard to do.

But to answer your question, the best way to set the RA and
Decl for use, is to...as you said...polar align, then point
your scope to a bright star of known RA and Decl...say Vega,
and while pointing to Vega, make sure your RA dial reads
18 hr 37 min and your Decl reads about +38 degrees 47 minutes.  But those small dials are so hard to read, if
you get within 1/2 degree of Decl and 10 min of RA, you'll
be very lucky.  
Better to star-hop..manually...and quicker too, IF you have
a reflex device like a telrad on your scope.  I would not
even own a scope without a telrad, in fact, my 30 inch
portable has 2 of them on it...one for initial sighting while standing on the ground, and one for up at the eyepiece on a 10 foot ladder.  A telrad gives you positive control over your scope, just like a rifle finderscope gives on a rifle.

Ok, technique is a learning experience...for instance, you
want to find the Ring Nebula...center your Telrad (and scope)
exactly midway between the stars Beta and Gamma Lyrae out
on the end of the parallogram in Lyra...and Bingo, there
it is.
Or a tougher one, M-51 (Whirlpool galaxy) is right off the
end of the Big Dipper...on a right angle off the last 2
stars of the handle end of the Big Dipper kind of southward.
So take the visual distance between Mizar and the end star
of the Dipper, 50% of that distance, and move scope on
a right angle southward a bit...and there is M-51.

Ghost of Jupiter (NGC 3242) no problem...locate the star
Mu Hydrae, offset scope 2 degrees due south, and Viola..
NGC 3242...anyway, that's how I recommend doing it.

To be honest, never used an equatorial mount...I'm all
DOB and alt-azimuth..my own goto and my own clock drive
with muscle power...no electric except for a telrad and
a mirror fan and secondary dew heaters.

Hope all this
helps,
Tom Whiting
Erie, PA

PS...for fine pictures of the 30 inch portable scope,
please visit our club website at:
http://www.velocity.net/~bwhiting/


FOLLOW UP:
Oh, BTW, if you take an interest in DSO's you are going
to have to move up the aperture scale...a 4.5 inch just
won't hack it except for the bigger and brighter DSO's...
the Pleiades, the Beehive, the Lagoon, and a few others...
minimum recommended aperture for DSO's is typically 8 or
10 inches, or better yet, bigger.  So your 4.5 is typically
only for lunar and planetary detail, and splitting the
wider, brighter, double stars.  That's what it was made for,
not faint DSO's.

Hey, scopes are like airplanes...all airplanes fly but
you don't send a fighter to do a bomber's job....
So if you really want to specialize in DSO's, you HAVE
to upgrade to a bigger aperture, unless all you want to
see is small, dim fuzzies with minimal detail.
For DSO's, you need more light grasp than what a 4.5 inch glass can do.
FWIW,
Tom Whiting

Answer
Deeb,
Yes!  Most definitely, as long as you stick with high
quality equipment...right now stick to the 3 best names...
Orion, Discovery, and Hardin who is the 'new guy on the block'
so probably has the best optics for the most reasonable price.

Because if you become really engrossed in the hobby like the
rest of us, you won't stay in your light polluted skies that
much, but rather travel out into the country to darker skies.
(So the key today is to remain portable at all times, even
with a 30 inch scope like I do)...BTW, I use an 8 inch
Coulter Newt. Reflector as my *finderscope* on the 30 inch.

I travel up to 3 hours on New Moon weekends, specifically
to Cherry Springs State Park in PA for a weekend enjoyment
out under a really dark sky.

I would avoid Celestron and Meade...what used to be top
names in the scope field...the former is bankrupt, and the
latter went public, so their quality of optics really took
a tumble, as they are out to please the stockholders.
(All in my opinion)

Also, its probably time to upgrade to a descent set of
atlases....you can't look for DSO's with just a little
planetsphere..you need a copy of Norton's Star Atlas or
Cambridge Star Atlas....I have the Cambridge....OR, eventually when you get up to larger apertures, you are
also going to need a copy of Uranometria Star Atlas, or
its equivalent...the last star charts you'll ever need
no matter what size aperture you go to.

Also, consider joining a club...look thru other peoples
scopes, determine what you want to specialize in, get other
opinions, etc. etc.  Then this will help you decide what
you want to eventually specialize in.  (Because you will
eventually specialize as there is too much out there not to.)
If you are strictly visual (not photo's) as I am, and many
others are, consider a DOB mounted scope with a telrad
for positive control allowing you to place the scope exactly where you want to point it....this allows you to spend more
for bigger and excellent quality optics without the use
of equatorial, which is only good for photography anyway;
also avoid those goto's and tracking motors...don't be
lazy...learn the night sky yourself...self teach yourself..
it ain't that hard....if you can memorize PA, OHIO, IND, ILL
4 adjoining area's, then you can also learn and memorize
Gemini, Cancer, Leo, Virgo...4 adjoining areas also.
It's basically the same thing.
You can't find the armory in Columbus OHIO until you first
know where OHIO is, then Columbus (a star), then offset
10 miles the the south to the Armory (a DSO)...this ain't
rocket science...we do exactly the same thing in the night
sky!
Hope all this helps,
Clear skies,
Tom Whiting
Erie, PA



PS..Oh, and for any future help, feel free to write me
directly at bwhiting@velocity.net


FOLLOW UP:

Oh, the upgrade itself is fantastic! (Using area = Pi r
squared)  You would be going
from about 15.9 sq. inches of glass, to 50.3 square inches
of glass....an over 3 times increase!  Better than one
whole magnitude gain (which takes 2.5 times increase)...in fact, your 4.5 is probably good
down to about 12th magnitude objects; an 8 inch is good
down to about 13.3 or 13.5 magnitude. Go for a 10 or 12 and
you'll reach 14th magnitude objects in a dark sky.
Clear Skies,
Tom W.