M51, I think...

Hi Tom !

"bwhiting" wrote in message
...
Actually Allison, I completely agree with you....but BV is a newbie,
and the 81, 82 combo is a pain in the butt to locate, even for an
experienced observer....in fact, tonight I tried to hit on those
for 5 minutes and gave up...Yes, I used the diagonal thru the
bowl of the dipper, but then what? There are just no bright guide
stars around to hone off on....so you search and search...sometimes
you hit it lucky...sometimes you don't....those have to be, by far,
the *toughest* of the Messier objects to locate just by eyeball (telrad)
'sighting'. I hate them. But love to see them, especially 82
at ultra high powers.

I agree with you on those two! I've tried for years to find them, giving up
after
10 minutes or so, then some years back I finally snagged them, thanks to a
C-8.
After that, I could find them without trouble in smaller scopes, proving
once
again that it might take a large scope to first sight something, but then it
can be
seen in smaller scopes, since you know where to look and what to look for.
Even professionals in ages past found his out; look at the case of the
Martian
moon.



Someone once told me there is a little triangle of faint stars near
the duo...but I have yet to find it, or see it. Plus you probably
need 6.5 mag skies to see the stupid triangle.
If anyone has any easy way of sighting in on this duo, I would certainly
appreciate any help in this regard.
Clear Skies,
Tom W.

Star charts don't show anything bright in the immediate vicinity; like some
other objects, there's little bright to guide you once you get close. Large
finders make it a bit easier, but it's not easy in my books.

BenignVanilla wrote:
Took advice from the group and tried for M51...I was looking in the area,
that some star charts said it would be in, and I found a faint fuzzy. In my
excitement I bumped the scope, and lost the image. Never found it again.
*sigh*

Perhaps, the biggest key to starhopping is learning to translate the
finderscope and eyepiece views to the charted representation of the sky. Begin
by determining the area of sky encompassed in your finderscope. For example, my
8x50 straight-through finder shows about 5-degrees of sky. Even a unit-power
finder, such as the Telrad, will often include one or more rings which
correspond to a range of field diameters.

Next, determine the orientation of the sky in your finder. Unit-power finders
maintian the normal orientation and, in most areas of the sky, you'll want to
arrange your charts with north at the top and east to the left. A traditional
straight-through finder will both invert (flip from top to bottom) and reverse
(flop from side to side) the view. If this is the kind of finderscope you have,
simply rotate the charts 180-degrees so they're upside down. They'll be easier
to compare against the finderscope view in most parts of the sky.

The celestial pole is one area where these tactics often doesn't work. For
example, most charts present the Big Dipper asterism in Ursa Major with the
handle to the left and the bowl to the right. But many observers wait to scour
this part of the sky until the Dipper is at its highest elevation, which is
when the Dipper is upside down.

If you use a unit-power finder, then you'll want to rotate your charts to put
north at the bottom and east to the right. Since a traditional straight-through
finder already inverts the view, you don't need to rotate your charts when
observing in this part of the sky.

Which charts do you use in the field? You mention referencing several charts
when searching for M51 (=NGC 5194 & NGC 5195). There are a lot of good chart
sets, out there, but it's best to find one primary set that you rely on for
most of your starhopping. Over time and with practice, translating the
finder/eyepiece views to the chart will become second nature. And as you gain
experience, you'll find it easier to reference multiple charts for starhopping.
But until you attain that comfort level, choose one set of charts and run 'em
into the ground.

Good hunting,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond

"bwhiting" wrote in message
...
snip
Someone once told me there is a little triangle of faint stars near
the duo...but I have yet to find it, or see it. Plus you probably
need 6.5 mag skies to see the stupid triangle.
If anyone has any easy way of sighting in on this duo, I would certainly
appreciate any help in this regard.
Clear Skies,
Tom W.


If you don't have the light gathering power of a finder scope, then, yes,
you'd probably need pretty dark skies to see the triangles. I use a 50mm
finder, and a distinct pair of little triangles is visible, pointing the way
to M81/82, even in light polluted skies.

"G Owens" wrote in message
rthlink.net...
snip
If you don't have the light gathering power of a finder scope, then, yes,
you'd probably need pretty dark skies to see the triangles. I use a
50mm
finder, and a distinct pair of little triangles is visible, pointing the
way
to M81/82, even in light polluted skies.

And, here is my method for finding M81/M82, based upon star hopping using a
finder with at least a five degree field.
http://home.earthlink.net/~gsowens770/home/FindM81/

bwhiting wrote in message ...
Someone once told me there is a little triangle of faint stars near
the duo...but I have yet to find it, or see it. Plus you probably
need 6.5 mag skies to see the stupid triangle.

True, they are not very easy to locate. That little isosceles triangle
(composed of Rho, Sigma 1, and Sigma 2 UMA) is what I use to locate
M81 and M82 - I usually find it with binoculars (it's very distinctive
with binoculars and there is nothing else like it in the area) and
memorize that spot on the sky, then point the telescope in the general
direction and it shows up in my finderscope. I think the stars are
around mag. 5.5 roughly. The two sigmas are about 20' from each other,
with Rho about 1 degree northwest of them.

Anyway, once you find the damned triangle, there is a pair of about
6th mag. stars about three degrees to the northeast that are seperated
from each other by about the same amount that Rho is from Sigma 1 & 2.
M81 lies about a degree east of the southernmost of this pair. Using
this method I can find it with a finderscope without too much trouble,
but I guess it might not work too well with a telrad (I'm not familiar
with those).

I believe that some people have claimed to see M81 with the naked eye
from extremely dark sites, but they might be lying.

(Jon Isaacs) wrote in message ...
[snip all]

At the top of this thread, BenignVanilla asked how to refind M51:[i]
lost the image. Never found it again.

Benign -

The following links display a couple of charts (15 deg and 5 deg
fields) at my personal web site marked with M51 and the two pointer
triangles mentioned by others in this thread. Star hops from Eta Usa
Maj and 24 CanV are also marked. These may help you get pointed back
in the right direction:

http://members.csolutions.net/fisher...deg_finder.gif

http://members.csolutions.net/fisher...deg_finder.gif

- Kurt

P.S. -

Online star charts like:

http://www.fourmilab.to/yoursky/

will allow you to print a horizon star chart for your city.

The "Your Sky" site also includes point-and-click features to print
star charts to find each of the Messier "M" objects:

http://www.fourmilab.to/yoursky/cata...atalogues.html

"bwhiting" wrote in message
...
BV, find dark skies, and put in your lowest power eyepiece. Take those
last two stars of the handle of the Big Dipper, and mentally draw a
90 degree angle downward (evenings, this time of the year)off that last
star in the handle...M-51 is pretty close to a 90 degree downward angle,
at about 1/2 the distance between those last two stars of the Big
Dipper, underneath the last handle star. (This is how I find it).
At least this gets you into the ball park, but you'll have to slowly
scan that region to find the fuzzy, M-51. Once found, then you can up
the power....
and plan on a 2 to 3 minute search, as its not exactly a 90 degree angle.
Hope this helps.
Clear Skies,
Tom Whiting

Thanks Tom...that is an alternate search method that I have not heard. I
will give it a try.

BV.

"David Nakamoto" wrote in message
...
Clear and Steady Nights for you Benign !

[getting into the lotus position and humming a little before . . . ]

And this is where, child, you learn the Zen of amateur Astronomy; never
get
too excited about seeing anything through a scope lest in your excitment
you
ruin the view, and deal quietly and calmly with disapppointment, even if
you're
alone in the dark.

This weekend I am going to Shenandoah to camp for four days with
friends...Hmm do I bring the climbing gear or the scope...Hmm...

BV.

"BenignVanilla" wrote in message ...
Awesome thanks!

Just to add my practical experience to the many others who provided
good advice in this thread, the first time I tried to find M51, I had
problems like you have described. I am principally a binocular
amateur. The first two times I tried to find M51, it was in less than
the best skies and the faint M51 was not visible. Like you, I became
suitably frustrated. Finally on the third try, after driving away
from the city and getting some 6.5+ skies, I was able to zero in M51.

In pointing your scope, I also find it helpful to know how to eyeball
rough angular measurements in the night sky.

The angular distances in the night sky can be estimated using your
fingers and hands:

Table of angular distance estimates:

width of index nail at arm's length: 1 degree
1st-2nd knuckles of clenched fist at arm's length: 3 degrees
2nd-4th knuckles of clenched fist at arm's length: 5 degrees
1st-4th knuckles of clenched fist at arm's length: 8 degrees
span of open hand at arm's length: 18 degrees
two clenched fists, end-to-end, at arm's length: 30 degrees

Adapted from Sidgwick's Amateur Astronomer's Handbook at p. 522.

First, identify suitable locator asterisms around the target object.

An asterism is a miscellaneous grouping of stars (on a
sub-constellation level) that suggest a pattern, like a triangle, a
square, a half-circle, a pointing line of stars, etc. An example of
an asterism are the two triangles marked on the sample M51 finder
chart. When composing useful asterisms, I find right-triangles,
pointing isoceles triangles, pointer-lines and half-circles to be the
most useful asterism patterns.

Second, eyeball the suspect location using the above technique without
your scope. M51 is about 8 degrees on the right-angle below eta Ura
Maj.

Third, point the scope finder at your eyeballed location.

Fourth, repeat the above and double-check you are pointing the scope
in the right general area.

Fifth, in the 5 degree finder field, get your bearings to your
locator asterisms and stars.

Sixth, use the low-power eyepiece and again get your bearings to your
locator asterisms and stars.

You may need to select another group of finder asterisms composed of
mag 8-9 stars for use in your low-power field.

Seventh, repeat the above and double-check you are using the right
locator asterisms.

Eighth, then follow your locater asterims to hone-in on the target
object.

Ninth, if it's still not there and you are sure you are pointing to
the right place, check the magnitude of the object and the background
sky brightness in the area of observation. The skies may just be too
light polluted to see it on that night. Defer to another, darker
night.

Occasionally, a random-search pattern can work. After you are honed to
the most probable location, eight circles of view-finder surround your
current field of view. (Visualize 8 circles packed around the outside
of one circle.) Go to each circle, one-at-a-time, overlapping a star
in the corner of your current field. After looking at one adjacent
field-of-view-circle, return to the home position.

Regards - Kurt

Second, eyeball the suspect location using the above technique without
your scope. M51 is about 8 degrees on the right-angle below eta Ura
Maj.

8 degrees? No way!!....M-51 is almost exactly 3.5 degrees from Eta UMa.
(Perhaps you were thinking of M-63 (Sunflower Galaxy) which
is almost exactly 9 degrees from Eta, and almost on that same line,
but not quite.
Clear Skies,
Tom W.