| |
Main
Date: 28 Jul 2006 11:40:12
From: Willie R. Meghar
Subject: 28 July 2006 UT Obs. Report
|
Latitude: between 45 and 46 degrees North
Telescope: 13cm (5.1 inch) f/6 apochromat
Zenithal Naked-Eye Limiting Magnitude: 6.0
Seeing: I to II on Antoniadi Scale
Magnifications used: 21x through 210x
The Session in Brief:
Pluto hunting, Barnard's Galaxy, and NGC 6818 (the planetary nebula
near Barnard's Galaxy). This session was also first starlight for a
new set of Orion Highlight Plossls (26mm, 20mm, 17mm, 12.5mm, 10mm and
7.5mm) and a Shorty-Plus 2x barlow.
Prior to darkfall a thin haze from a distant fire was apparent, most
noticeably near the horizon; but the entire sky was affected to some
degree. Nevertheless, I went ahead with a plan that started with a
Pluto hunt (thanks to Martin Howell's suggestion).
After darkfall an aurora was quite apparent in the north. The display
was fairly bright encompassing quite a bit of sky; but devoid of any
noteworthy structure.
The combination of the thin haze and aurora adversely affected my
limiting magnitude by 0.5 magnitudes. Nevertheless, since I had
planned to shoot for Pluto I made that my first target. I gradually
increased magnification until I got to a 7.5mm Plossl. Then I settled
down and sketched the star field in the region around Pluto's known
position. A few faint stars were seen that were absent from my GSC
printout. One of these would briefly appear near enough to Pluto's
known position to gain some serious suspicion. I switched to a 6mm
Orthoscopic eyepiece and the suspicious star's presence became more
convincing, but was still invisible more often than it was visible.
This star's position seemed to differ from Pluto's position by just
enough to raise a bit of doubt, yet it was tantalizingly close. I'll
need two better observations separated by at least a day before I'll
feel confident that I've found Pluto. On better nights, during
previous years I've seen Pluto with this scope as well as with a 10
inch Newtonian stopped down to a 4 inch clear aperture.
I plopped in the 26mm Plossl, pointed the scope at Dabih (Beta
Capricorni) swept in RA and was able to detect Barnard's Galaxy as
soon is it entered the field of view. The galaxy was large (about a
quarter of a degree in diameter), very faint, and very diffuse. The
galaxy seemed a little better with a 27mm Panoptic. I finally dropped
down to 21x with an old Meade 40mm SWA eyepiece. I felt the galaxy
was better with the Panoptic. The background sky may have been
brightened too much with the 40mm eyepiece and its large exit pupil.
Next I experimented with the Plossls, gradually increasing the
magnification on Barnard's Galaxy. The 20mm and 17mm Plossls showed
the galaxy; but with the 12.5mm I was beginning to need a bit of
imagination in order to maintain the galaxy's visibility. That seemed
to be the right place to stop. At least in my memory, this galaxy was
better a few nights ago using mounted 25x100 binoculars. That was a
more transparent night with a magnitude 6.5 sky.
On to NGC 6818, the planetary near Barnard's Galaxy. This object was
bright and easy to identify even at low magnification. Unlike nearby
stars of similar brightness, direct vision would render the planetary
invisible. Also, at low power the planetary had a slightly 'fuzzy'
appearance that helped make it look just a little different than a
star.
This was a good object to increase magnification on (besides, I wanted
to try out a new barlow). I slipped in the barlow and went through
all the Plossls. The view with the barlowed 7.5mm Plossl was very
nice and sharp (remember, the seeing was quite good this night). The
planetary at high power was a bright, featureless, circular disk --
looking very much like a distant gas giant planet. A star was visible
about two planetary diameters to the east of the nebula.
I finished off the evening with a quick look at M13, again going
through the barlowed Plossls. At all magnifications the stars in the
cluster would 'snap' into focus at one precise position as the focuser
was worked. This evening may have been rather poor in the
transparency department; but it was better than usual in seeing. I'm
very happy with the performance of the new Plossls and barlow, at
least for deepsky observing.
Willie R. Meghar
|
|
| |
Date: 28 Jul 2006 19:43:59
From: SkySea
Subject: Re: 28 July 2006 UT Obs. Report
|
Thanks for the report.
A couple of ideas:
I've found that if Pluto is close enough to another star, you can see
Pluto's position change over the course of one night (when not near a
standstill). You may not need to wait for another night.
It will vary enough over 24 hours that the field of view can be
radically different. So I'd recommend sketching both where you think
you see it on the observing night (later, "Aha! That was it!"), and
for the next night. That way, you'll already have accounted for all
the stars you can see in your scope, so anything new would likely be
Pluto (unless you're seeing another moving object).
Happy hunting!
>On Fri, 28 Jul 2006 11:40:12 -0600, Willie R. Meghar
>Then I settled
>down and sketched the star field in the region around Pluto's known
>position. A few faint stars were seen that were absent from my GSC
>printout. One of these would briefly appear near enough to Pluto's
>known position to gain some serious suspicion. I switched to a 6mm
>Orthoscopic eyepiece and the suspicious star's presence became more
>convincing, but was still invisible more often than it was visible.
>This star's position seemed to differ from Pluto's position by just
>enough to raise a bit of doubt, yet it was tantalizingly close. I'll
>need two better observations separated by at least a day before I'll
>feel confident that I've found Pluto. On better nights, during
>previous years I've seen Pluto with this scope as well as with a 10
>inch Newtonian stopped down to a 4 inch clear aperture.
=============
- Dale Gombert (SkySea at aol.com)
122.38W, 47.58N, W. Seattle, WA
http://flavorj.com/~skysea
|
| |
Date: 28 Jul 2006 11:25:57
From: RMOLLISE
Subject: Re: 28 July 2006 UT Obs. Report
|
Willie R. Meghar wrote:
>
> The Session in Brief:
> Pluto hunting, Barnard's Galaxy, and NGC 6818 (the planetary nebula
> near Barnard's Galaxy). This session was also first starlight for a
> new set of Orion Highlight Plossls (26mm, 20mm, 17mm, 12.5mm, 10mm and
> 7.5mm) and a Shorty-Plus 2x barlow.
>
Hi:
If you can do Pluto with a 5-inch refractor, my hat's off to you. I did
it some years back with a 12.5-inch Newtonian from the dark skies of
the Texas Star Party. My notes?
"Pluto can be held fairly steady with direct vision at about 400x, but
it is D-I-M!"
Keep us posted on your efforts.
Peace,
Rod Mollise
Author of:
Choosing and Using a Schmidt Cassegrain Telescope
and
The Urban Astronomer's Guide
<http://skywatch.brainiac.com/astroland >
The Annual SCT User Imaging Contest is Underway!
<http://www.rothritter.com/contest/2006/ >
|
| |
Date: 02 Aug 2006 12:36:10
From: Arnold
Subject: Re: 28 July 2006 UT Obs. Report
|
Willie R. Meghar wrote:
> At least in my memory, this galaxy was
> better a few nights ago using mounted 25x100 binoculars. That was a
> more transparent night with a magnitude 6.5 sky.
Good day
I'm interested in buying a pair of 25x100's later on.
What make of binoculars are you using? How do you mount them?
Your general impressions?
Regards
A
|
| | |
Date: 02 Aug 2006 13:21:54
From: Willie R. Meghar
Subject: Re: 28 July 2006 UT Obs. Report
|
Arnold wrote:
>Good day
>
>I'm interested in buying a pair of 25x100's later on.
>
>What make of binoculars are you using? How do you mount them?
>Your general impressions?
Hi Arnold,
I use Orion 25x100s. The mount I use is based on the pattern shown on
the following web page:
http://www.rangeweb.net/~sketcher/Binos.html
This mount isn't well suited for sharing views with other observers,
nor is it suitable for viewing objects at high elevations. Other than
those disadvantages it's a pleasing, economical, and effective mount
for astronomical and terrestrial use.
My general impressions of the Orion 25x100s:
As long as the object of interest is kept near the center of the field
of view (where the image is sharpest), these binoculars provide
exceptional performance.
I'm very pleased with the deepsky performance (star clusters,
galaxies, nebulae, etc.) when used under a magnitude 6+ sky. Some of
the views are quite awesome! The moon is a very impressive sight as
well -- sharp with a great deal of visible detail.
Eye lenses are large. Eyecups are closely matched to best eye
placement. Eyecups can be folded down for use with eye glasses if
necessary.
Collimation (at least in my pair of 25x100s) is for all practical
purposes 'perfect'.
One problem (for some people) is the interpupillary distance. Minimum
IPD is about 63mm. By removing some aluminum from the hinges it's
possible to bring this down to 60mm (at which point the two barrels
make contact).
If one wants to be nit-picky one may criticize edge of field
performance; but as long as one is concentrating one's attention near
the field center (using binoculars in a manner in which binoculars
should be used) this will go unnoticed. Likewise, some false color
will be visible along the lunar limb; but this can be easily ignored
by those who are more interested in observing details on the rest of
the lunar disk.
Exit pupils are not perfectly circular disks; but they're 'close
enough' for those more concerned with looking *through* the binoculars
than looking *at* the binoculars. For the price, one cannot and
should not expect perfection. I'm happy with my Orion 25x100s and
have no intention of getting rid of them.
Willie R. Meghar
|
| | | |
Date: 11 Aug 2006 10:37:24
From: Arnold
Subject: Re: 28 July 2006 UT Obs. Report
|
Willie R. Meghar wrote:
> Hi Arnold,
>
> I use Orion 25x100s. The mount I use is based on the pattern shown on
> the following web page:
>
> http://www.rangeweb.net/~sketcher/Binos.html
Hi Willie
Thank you for the information on the Orions.
My local planetarium imports Orion equipment, so it will be a bit
cheaper to order from them rather than buying from Apogee Inc and having
it shipped here with Priority delivery. The Priority service is so much
more expensive than normal shipping but I am not really willing to take
a risk with snail mail either.
Take care
A
--
25° 45' S
28° 12' E
GMT+2
Join the Planetary Society
http://www.planetary.org
|
| |
Date: 11 Aug 2006 09:50:28
From: darkness.lumpy@gmail.com
Subject: Re: 28 July 2006 UT Obs. Report
|
Willie R. Meghar wrote:
> Next I experimented with the Plossls, gradually increasing the
> magnification on Barnard's Galaxy. The 20mm and 17mm Plossls showed
> the galaxy
Hi Willie,
Enjoyed your report. Curious is you could detect any HII regions in
Barnard's Galaxy either in your 5.1" refractor or the binos.
|
| | |
Date: 12 Aug 2006 00:18:10
From: Willie R. Meghar
Subject: Re: 28 July 2006 UT Obs. Report
|
"darkness.lumpy@gmail.com" wrote:
>Enjoyed your report. Curious is you could detect any HII regions in
>Barnard's Galaxy either in your 5.1" refractor or the binos.
Hi Lumpy,
I saw no trace of HII regions with either pair of large binoculars. I
recall seeing (or imagining) at least one piece of "lumpy brightness"
with the refractor when using, IIRC, the 12.5mm (62x) eyepiece; but
the galaxy itself was enlarged to the point of being mostly invisible.
I didn't mention it in my report, but after seeing or imagining this
lump I immediately thought "HII region or stellar concentration". At
that point I tried a filter (I think it was a 1.25" Ultra-Block. I
would have had to pull out the diagonal in order to screw in my 2"
OIII). With the filter only a few stars remained visible -- nothing
else. Any galaxy or lump of brightness was completely invisible.
A night of better transparency will be needed before I'll be able to
clarify the observation. If the night had been more transparent I
would have taken more time and tried the OIII filter.
Willie R. Meghar
|
|
