A Bear Hunt

The last few nights have been clear and crisp in northern Arizona. Tuesday
night, I made the 15-mile drive to Anderson Mesa, Lowell Observatory's dark sky
site southeast of Flagstaff, for a short observing session. Two hours later,
I'd made observations and sketches of NGC 2742, NGC 2768, NGC 2841 (all three
are Herschel 400 objects), and the galaxy cluster involving NGC 2767, NGC 2769
and NGC 2771. All can be found in Ursa Major, the great bear, which is well
placed for observing right after sunset.

NGC 2742 (http://members.aol.com/billferris/n2742.html )
I observed this 11.4 magnitude spiral galaxy at 129X in the 10-inch Starfinder
Newtonian. NGC 2742 covers a 3'x1' area along an east-west axis. Its oval form
is highlighted by a slightly brighter core region. The bright star immediately
to the northwest is 7.8 magnitude HD 77726. A trio of 11th through 13th
magnitude stars stands sentry immediately to the west-southwest. 9.2 magnitude
HD 78124 is seen just inside the field boundary, 13' to the east. Eighteen
additional stars complete the view. NGC 2768 is located just beyond the field
of view, some 40' to the southeast. Look for NGC 2742 in the snout of the Great
Bear, about 5 degrees south-southeast from 3.3 magnitude Omicron (1) Ursae
Majoris.

NGC 2768 (http://members.aol.com/billferris/n2768.html )
I observed this 9.8 magnitude elliptical galaxy in my 10-inch Newtonian at
129X. The galaxy is centered and covers an area of 2'.5x2'. The faint outer
region is lost against the night sky. NGC 2768 features a bright stellaring at
the core and is elongated along an east-west line. A 10th magnitude star shines
about 5' due north. A star of similar brightness is seen 4' to the northwest.
9.0 magnitude HD 78297 simmers just inside the edge of the field some 15' to
the northwest of NGC 2768. Another 22 field stars complete the view. You'll
find NGC 2768 about 1.5 degrees south of 5.2 magnitude 16 Ursae Majoris. NGC
2742 is also nearby, just 40' to the northwest.

NGC 2841 (http://members.aol.com/billferris/n2841.html )
Ursa Major is home to several large, bright galaxies. NGC 2841 is among these
but not nearly as well-known as others, particularly those in the Messier
catalog. This 9.2 magnitude Sb-type galaxy was observed at 129X in my 10-inch
Newtonian. Elongated northwest-to-southeast, NGC 2841 covers an impressive
5'x2'.5 area. The inner 2'x1' region appears decidedly brighter and is
punctuated by a stellar core. An 11.1 magnitude star stands alongside the
northwest tip of the galaxy. 8.5 magnitude HD 80566 blazes some 4'.5 to the
east. Eighteen additional field stars provide context. NGC 2841 is located in
far southwestern Ursa Major, about 2 degrees southwest of 3.1 magnitude Theta
Ursae Majoris.

NGC 2767, NGC 2769 & NGC 2771 (http://members.aol.com/billferris/n2767.html )
Galaxy clusters are among my favorite objects to observe. It's astounding to me
that several stellar gothams can be viewed within the same slender patch of
sky. That's like collecting Tokyo, New York City and LA, side-by-side, on the
same patch of land. One such grouping includes NGC 2767, NGC 2769 and NGC 2771,
three galaxies in western Ursa Major. My observation was made at 129X in the
10-inch Starfinder. NGC 2767 is the fainter of the trio, with a blue magnitude
of 14.8. It's slender form is aligned roughly east-west and over a 60"x15"
area. 4' to the east, NGC 2769 emerges as a 60"x30" patch elongated
north-south. This Sa-type galaxy has a blue magnitude of 13.9. Finally, NGC
2771 resides 3' south of NGC 2769. This SBab-type barred spiral presents as a
30" diameter oval, very faint with a blue magnitude of 13.6. All three have
radial velocities of 4820 km per second per megaparsec to 5053 km per sec per
megaparsec, indicating they reside about 250 million light-years from the Milky
Way. Twenty-one stars populate the field. Among these is HD 78792, a 6.7
magnitude star near the eastern field boundary.

Regards,

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

I am definitely going to bring a copy of this posting out with my sons and
me on our next observing session! A 10" newt may not do a great job for
observing spiral arms, etc, but it does nevertheless provide a lot of fine
galaxy views. I think this is one area where a 10" scope is much superior to
an 8" scope. A few of us in our club claim to see spiral structure in M51
and M101 at 10", while others kid us a lot about "averted imagination".
Clearly, not all eyes (or imaginations) are created equal. Great info -
thanks.

Dennis

Dennis Woos confides:

A few of us in our club claim to see spiral structure in M51
and M101 at 10",

Big pupils. . .I wish I had 'em.


--
Martin

Martin R. Howell wrote:

Dennis Woos confides:

A few of us in our club claim to see spiral structure in M51
and M101 at 10",

Big pupils. . .I wish I had 'em.

--
Martin

Hey, last Saturday I was convinced that I'm seeing spiral
structure in M51 in my 8". And that was under much less
than ideal conditions - not very good transparency and some
light pollution.

So, now I have to ask myself: Do I have really good eyes or
really good imagination? :-)

....but also: Does it make difference which one is the case?

- Alex

Alexander Avtanski wrote:
Hey, last Saturday I was convinced that I'm seeing spiral
structure in M51 in my 8". And that was under much less
than ideal conditions - not very good transparency and some
light pollution.

So, now I have to ask myself: Do I have really good eyes or
really good imagination? :-)

Dunno. It depends on what you mean by "hints of spiral structure." I
think I've seen the spiral structure in my 5-inch SCT, but that may just
mean I set myself a lower bar at the time for "hints" than other people
would. For what it's worth, I would not submit that one as a reliable
observation.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Brian Tung says:

I think I've seen the spiral structure in my 5-inch SCT, but that may just
mean I set myself a lower bar at the time for "hints" than other people
would. For what it's worth, I would not submit that one as a reliable
observation.

Haven't I heard somewhere that perception is reality or something to that
effect? I would say that if you think you've seen something that by its
nature is elusive in even a somewhat larger instrument then that is a
positive sighting. . .at least for the observer involved.


--
Martin

Martin R. Howell wrote:
Haven't I heard somewhere that perception is reality or something to that
effect? I would say that if you think you've seen something that by its
nature is elusive in even a somewhat larger instrument then that is a
positive sighting. . .at least for the observer involved.

Do you believe everything you've heard?

More seriously, I'm not sure what you mean by "positive," and I'm also
not sure whether you're supporting my observation or casting doubt on it,
but I myself would not consider what I saw a reliable observation. In
other words, there is a significant chance that I was mistaken. (I'm
sure at the time I didn't think so, but in retrospect, there has to be
that chance.)

The reason I *did* think I had seen it, however, was that my immediate
impression was, "Hey, something is wrong; I'm seeing the wrong thing,
because the spiral is going the wrong way." Only just afterward did it
occur to me that I was observing through an SCT with a star diagonal,
and in such an arrangement, the spiral *should* go "the wrong way."

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Alex posted:

Hey, last Saturday I was convinced that I'm seeing spiral
structure in M51 in my 8". And that was under much less
than ideal conditions - not very good transparency and some
light pollution.

So, now I have to ask myself: Do I have really good eyes or
really good imagination? :-)

I think that you probably did see the sprial structure, as I have seen it in
my own 8 inch Newtonian on a number of occasions (from a dark sky site of
course). It isn't quite as obvious as the structure is in my 10 inch (where I
can see some of the individual arm segments or the larger star clouds), but
you can easily see it as more than just mottling. One night at my dark-sky
site, I stopped my 10 inch down to 94mm (3.7 inches) to see how M51's
appearance changed. M51 did not show clear spiral structure at that aperture,
but it did show sort of a diffuse irregular ring-like structure around the
brighter core which was distinct enough from the nuclear region to be quite
noticable. At 80mm, the galaxy looked like a circular fuzzy spot with maybe
just a hint of mottling, a small brighter core, and the companion galaxy next
to it. Below 80mm, all hints of mottling vanished. Last night, I had the
NexStar 9.25GPS on M51, and it was one of the finest views of the galaxy I
have ever had with such an aperture. The arms were dim but quite obvious, and
the galaxy took even 297x well, although it was better at 168x. The night was
good enough that I could even glimse the faint connection between M51 and its
companion, along with one of the tidal plumes. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

"Brian Tung" wrote in message
...
Martin R. Howell wrote:
Haven't I heard somewhere that perception is reality or something to
that
effect? I would say that if you think you've seen something that by its
nature is elusive in even a somewhat larger instrument then that is a
positive sighting. . .at least for the observer involved.

Do you believe everything you've heard?

More seriously, I'm not sure what you mean by "positive," and I'm also
not sure whether you're supporting my observation or casting doubt on it,
but I myself would not consider what I saw a reliable observation. In
other words, there is a significant chance that I was mistaken. (I'm
sure at the time I didn't think so, but in retrospect, there has to be
that chance.)

The reason I *did* think I had seen it, however, was that my immediate
impression was, "Hey, something is wrong; I'm seeing the wrong thing,
because the spiral is going the wrong way." Only just afterward did it
occur to me that I was observing through an SCT with a star diagonal,
and in such an arrangement, the spiral *should* go "the wrong way."


I certainly was not casting doubt on your observation. . .I was affirming
that to you it may have been undifferentiable from an undeniable sighting
when using such a small scope -- insofar as to what detail is revealed to
the YOUR eye.

But. . .what is satisfying for one is not necessarily satisfying for all.
Believe me, I found this out the hard way when I submitted an observation
report to s.a.a. which included some nebula in which I claimed to have seen
a rather straight and pronounced edge. This was maybe 18 months or so ago.
I think it was Tom Trusock who replied that he could not see what I was
referring to. (I know, a preposition is a hell of a thing to end a sentence
WITH). ;o) I checked the image of it on LEDAS and the "straight edge"
was not there either, yet, at the time, I was so sure of what my eyes saw
and brain perceived that I would have bet a hundred bucks that the straight
edge was real. I'll have to take another look at it if I can locate its NGC
number in my log.

As for M51, with my 12.5 inch dob and a 6th magnitude location, the best I
can do on the arms is to get a core surrounded by a halo which appears to be
*slightly* more congested in a pattern of regularity which suggests an armed
structure.

--
Martin

In article ,
David Knisely wrote:



I think that you probably did see the sprial structure, as I have seen it in
my own 8 inch Newtonian on a number of occasions (from a dark sky site of
course). It isn't quite as obvious as the structure is in my 10 inch (where
I
can see some of the individual arm segments or the larger star clouds), but
you can easily see it as more than just mottling. One night at my dark-sky
site, I stopped my 10 inch down to 94mm (3.7 inches) to see how M51's
appearance changed. M51 did not show clear spiral structure at that
aperture,
but it did show sort of a diffuse irregular ring-like structure around the
brighter core which was distinct enough from the nuclear region to be quite
noticable. At 80mm, the galaxy looked like a circular fuzzy spot with maybe
just a hint of mottling, a small brighter core, and the companion galaxy next
to it. Below 80mm, all hints of mottling vanished. Last night, I had the
NexStar 9.25GPS on M51, and it was one of the finest views of the galaxy I
have ever had with such an aperture. The arms were dim but quite obvious,
and
the galaxy took even 297x well, although it was better at 168x. The night
was
good enough that I could even glimse the faint connection between M51 and its
companion, along with one of the tidal plumes. Clear skies to you.


One three nights in February 1993, while at Winter Star Party in the
Florida Keys, I could detect both the spiral structure and the bridge
separating M51 and NGC 5195. In all three cases, I was observing by
myself in the early morning hours, when M51 was at altitudes of 60-70
degrees.

Seeing and transparency at the time were excellent, and I spent at least
an hour on only M51. The bridge was a certainty whenever I would let
the companion drift into view first, before the light of M51 could
interfere.

The scope employed was my 6" f/9 AP Starfire, with magnifications of
160X and 190X providing the best views. I have not repeated the
observation with that scope since, although I have also not considered
it a priority. My 18" f/4.5 usually shows the spiral structure quite
easily in a decent sky.

Starry Skies,
Rich