M101 ?

What is the trick to seeing M101. I am using an 8" SCT and accurate star
maps....but it just will not materialize.

Gary Earle posted:

What is the trick to seeing M101. I am using an 8" SCT and accurate star
maps....but it just will not materialize.

1. A dark moonless sky away from bright city lights.

2. Low to moderate power (40x to 60x) and a wide field of view (as close to a
full degree as you can get).

3. Good dark adaptation (15 minutes in total or near total darkness).

4. Proper use of averted vision (ie: look away from the object, as the edge of
the eye's field of view is more sensitive to light than the center).

5. Getting to the proper field. There aren't a lot of good guide stars in the
area, so it can be tough to get on the correct location even with good star
charts. I like using the "chain" of 5th magnitude stars (81, 83, 84, and 86
Ursa Majoris) which runs from Mizar up to the east to within about 1.5 degrees
of M101's location. If you can get onto 84 Ursa Majoris, just have your scope
on a wedge and slew it about 2.4 degrees straight east of it to get to M101.

6. Knowing what to expect. M101 is large (nearly half a degree across) and
has a *very low* surface brightness (14.0 mags/square arc second), so it will
look like a vague brightening of the sky background with a slightly brighter
middle. With some study, some vague mottling can be seen, but otherwise, this
spiral can be difficult to see (I regularly see it in my 8x50 finderscope
however). For a somewhat easier target, try M51 or the nice pair of galaxies
M81 and M82. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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"Gary Earle" wrote in message
newsOljc.1419$iy5.503@okepread05...
What is the trick to seeing M101. I am using an 8" SCT and accurate star
maps....but it just will not materialize.



1) A dark sky
2) Dark adapted vision

M101 has a low surface brightness and it is very hard to find in a light
polluted environment. One thing you might try is to slowly move your scope
around the location where M101 would be. As your eyes are sensitive to
motion, it will be easier to pick up the faint smudge that is M101 as it is
moving within your field of view.

Anyway, what you will be able to make out in an 8" scope will probably be
nothing like the beautiful spiral you see in astrophotos.

Jeroen.

"Gary Earle" wrote in message
newsOljc.1419$iy5.503@okepread05...
What is the trick to seeing M101. I am using an 8" SCT and accurate star
maps....but it just will not materialize.

Get out of the city and go to your best dark sky site. From the listed
magnitudes, you would expect it to be easy. But those list the total
magnitude and M101 is really spread out. Surface brightness is low. The only
way to have enough contrast between M101 and the sky is to get extremely
dark skies.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/
And the Lunar Picture of the Day http://www.lpod.org/
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