(IAAC) Obj: M 27 - Inst: 24 cm dobsonian, f/6.6

Thu Aug 26 12:57:12 EDT 2004

Hi Lew:
Your comments triggered a remembrance of an outrageous night at sea level when seeing and transparency was outstanding. One of the best ever. Clark Creek is located on the Pamlico Sound near Stumpy Point with an unobstructed view to the South and East toward the Atlantic Ocean. (75:51:12W; 35:35:53N)
The following is pasted directly from the evenings report.

‘Fabulous Skies at Clark Creek’

6 Nov. 2002
14:30 EST
I arrived at the Clark Creek observing site in time to enjoy a colorful sunset between torrential showers and swarms of mosquitoes. As the rains came down I waited around for Eric Honeycutt. I finally decided that it was a bad evening and I wasn’t about to get out to be carried away by the hoards of flying villains so I drove back to the highway to wait for Eric. Along about 18:30 Eric arrived and he wanted to go on to the observing site and wait out the showers. He had verified that clearing was eminent, so back to the end of the access road named Pamlico Road that ends in the swampy grassland along the north side of the Pamlico Sound Between Stumpy Point and Engelhard south of US264.

Sometime between 19:00 and 20:00 the sky mostly cleared and as the rain soaked into the sandy soil we decide to set up the scopes and prepare to stay the course. We laid every thing out on a tarp, but by the time we had both the 12” SCT and the 22” Dob set up the puddles were all gone, but things were still wet. A breezy wind was blowing which helped dry things and kept the mosquito hoards at bay.

While there were clouds scudding by, we noticed a weak but broad light dome to the north about where the bombing range is located and another to the west at Engelhard. As the clouds thinned out the light domes all but disappeared and a few scattered clouds were like black ink blots moving across the sky. The sky transparency was phenomenal and seeing not so good toward the north. However to the south and east out across the water the seeing had to be 8/10 or better.
The 3rd diffraction ring was visible most of the time in the 12” even if it did quiver a lot. The transparency was great right down to the horizon. About a quarter of a mile to the south of Clark creek is a levee with small scrub pines and the stars of Orion were showing through the limbs of the trees as the constellation rose above the horizon. Absolutely unbelievable transparency. Later as Triangulum was nearly at the zenith, M33 appeared as a fingerprint on the celestial window. It was the first time I have seen it without carefully star hopping to get the correct location and then seeing it as a faint smudge with averted vision. It was as easy to see as M31 is normally. This time it was a real attention getting experience to be remembered forevermore. I don’t believe I ever remember a better sky anywhere and I have seen some beautiful skies in the Carolina and Virginia mountains and the Southwest and in the high plateau in Washington State, but none were remembered to be as good as tonight at Clark Creek and it at sea level. 

I observed M33 with the 12” and the spiral arms really stood out against the blackness of the sky, black not deep blue. NGC604 was obvious and IC143 was suspect. All this in an f:10; 12”; SCT. It just isn’t possible, but I saw it, no doubt about it. The view was just overwhelming. I revisited NGC206 in M31 to confirm what I recorded at MASP on 02, Nov., 2002, on Figure D34A, I recorded Globular Cluster, G52 near NGC206. It is the first truly extragalactic Glob that I am aware of seeing. I observed it at MASP with the 22”, but I could also see it in the 12” at Clark Creek.

Regards,
Jim Anderson
************************************************************************

From: "Lewis J. Gramer" <lgramer at upstream.net>
Date: 2004/08/26 Thu AM 11:32:54 EDT
To: "'IAAC: Internet Amateur Astronomers Catalog of Visual
	Deep-SkyObservations'" <netastrocatalog-announce at visualdeepsky.org>
Subject: Re: (IAAC) Obj: M 27 - Inst: 24 cm dobsonian, f/6.6

Limiting Magnitude is indeed a very observer-specific thing. I don't
believe it's COMPLETELY subjective - otherwise, the meteor data-
gathering methods of the IMO would never work! And recent success
in predicting meteor outbursts proves that they do in fact work well.

Anyway, that's off-topic for IAAC: but I did want to mention that LM
is primarily dependent on clean air, and on lack of light pollution -
and NOT necessarily on altitude above sea level! I observe meteors
(and deep sky) frequently from spots around the US (and one very
wonderful week in China for the 2001 Leonids). And my experience
is that skies in the Florida Keys - if one can still manage to escape
the ubiquitous European-style resort hotels that are sadly marring
the landscape more and more down there - can be just as dark as
those at altitudes of 2000m or more in the American Southwest.

The only observing site that I can unequivocally say has shown me
better Limiting Magnitudes than I often got on the best nights from
the Florida Keys in the past decade - would be the 2700m site on
Mauna Kea in Hawai'i! (The actual observatories up at 4100m could
assuredly give still better skies - but my flatlander, swamp-bottom
lungs sadly just could not manage too well up at that height! :->)

Now this isn't to say that the skies at SOME sites near sealevel
aren't completely overcome by heavier moisture condensation in
the air - coupled with light and air pollution... My observing in the
Florida Everglades in recent decades makes that sadly clear.

All of that said, of course, there is some reasonable debate as to
whether EXTENDED faint objects are better perceived at altitude,
than they are at sea level: I think there is definitely something to
this, particularly near the tropics, where the effects of airglow (the
natural emission of night-time atmosphere that has been bathed
in sunlight all day) can be very prominent indeed from dark sites.
And of course, where you have less air, there's also less airglow!

Clear skies all!
Lew

-----Original Message-----
From: netastrocatalog-announce-bounces at visualdeepsky.org [mailto:netastrocatalog-announce-bounces at visualdeepsky.org] On Behalf Of
Tudorica Alexandru
Sent: Thursday, August 26, 2004 7:32 AM
To: IAAC: Internet Amateur Astronomers Catalog of Visual Deep-SkyObservations
Subject: RE: (IAAC) Obj: M 27 - Inst: 24 cm dobsonian, f/6.6

That sky I had only once in my entire astronomer life and i think that it was an atmospheric anomaly, becouse from that point the
best sky I had it was only +7.0. I determined the limit magnitude then with the limit magnitude areas of IMO, in Boo an Cyg, where I
almost didn't had almost any star to count. (only three left). I am at 260 m altitude, but the highest observing place i can get in
Romania is at about 1800m. Two weeks ago at the perseids I had at best +6.94....
  And don't forget that the limit mgnitude is an subjective thing...
Clear skies, 
Alex

Natko Bajic <natkobajic at yahoo.com> wrote:

Wow, +7.45 sky! I had once about 6.75, maybe even 6.8,
from my observation place, 40km from cities! Amazing,
but more than a half magnitude deeper looks incredible
from "normal" altitudes. That should be over 2000m or?
We in Croatia do not have so high mountains...

I saw color in M 42 once, with 12cm refractor, but
with averted vision only, and just in traces...

Regards,N.

--- Tudorica Alexandru wrote:

> I did't used any sort of nebula filter, but i
> usually see different colours than others in nebulae
> and comets. I saw once on M 27 a green hue, but
> witht the 9 cm refractor, in +7.45 sky... I see
> colours in telescope very rare, only three times
> until now.
> Clear skies,
> Alex
> 
> 
> 
> 
> "Lewis J. Gramer" wrote:
> This was an interesting log, Alex. Were you using
> any sort
> of nebula filter (e.g., NarrowBand, UHC, OIII, or
> similar),
> when you noted the color of the Dumbbell as
> "yellow-red"?
> 
> Clear skies!
> Lew
> 
> 
> 
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