Saturday night found me at Chews Ridge along the Tassajara road, 2.6
miles from the crest at moonset with my flocked C14. I was limited by
time, so I hit a few peices of eye candy with 31mm and 22mm nagler eps
(126x and 178x). Finder scope was 9x50mm stock. The scope did not have
time to cool before I started to view; it might have been even more
breathtaking. I noted hot air pillars when I looked at Merak at 126x.
No twinkling of fant stars was apparent, and M13 was visible with the
unaided eye easily with averted vision, and fleetingly with direct vision.
M51 was easily presented in the finder, and with the C14 at 178x was
spectacular, with spiral arms traced around the entire nucleus. The
bridge to the satellite was clearly observed. Best view ever.
The view of M13 I had was simply the best I ever had through my C14.
The ball was brightly resolved to the core. I had the impression that
there wasn't anything more to resolve. M3 was great, resolved to the core.
M97 showed up as a huge cotton ball at 178x. It was visible in my
finder, but the eyes were only fleetingly visible at this mag, although
my companion saw them right away.
M108 and M109 were equally easy. M108 exibited a clearly mottled
appearance. M82 had the distinct mottled appearance as well.
M101 was found in a few moments in my finder, and filled the field at
126x; my observing companion also noted some of the HII regions near the
edge of the field.
BTW I got there late and had to search for my companion's dog which
decided to jump out at the crest, if anybody was bothered by my
headlights at the fire road at 3.1 miles past the crest I apologize.
Unfortunately, fell asleep sometime around 3am and never saw the
comets. Can't wait to get out again in two weeks.
****************************************
Yes, I believe seeing conditions matter a whole deal to the faintness of
the objects you'll be able to see, and the quality of views you receive,
all things being equal. Seeing may have as much a deleterious effect as
transparency (just plain secZ or atmospheric extinction).
For example, a night that shows 1" seeing may allow you to see a 6.5 mag
star under good conditions. On another night with 2" seeing, the light
will be more or less spread out with 1/4 the light across the circle
atmospheric blur. Hmmm...that is log(4) = 0.6 magnitudes. Not a small
difference.
If you consistently get 0.75" at Chews Ridge, and get 1.5" at FP (these
would both be good nights, I think) then you are picking up an extra 0.6
mag in addition to the darker sky.
But does it equate to a better view for extended objects? Maybe not
for nebulae and galaxies, which are below the resolution limit of most
scopes, but on globulars, where a large telescope is going to be able to
show points of light, I think you are going to see a great benefit in
the number of stars resolved, and conversely the view.
David Kingsley
> Ralph Seguin wrote:
>
>> I don't really anticipate much variation in seeing from one site to
>
>> another, but you never know.
>
>
>
> I think seeing conditions deserve much more attention than they
> usually get when choosing observing sites. The steadiness of the sky
> makes a huge difference in the amount of detail that can be seen in an
> observing session, and how faint you can go when pushing the limits
> for hard objects. Seeing often depends on local topology and is not
> well captured by light pollution maps or typical measures of sky
> darkness. I think there is a lot of variation in seeing from one
> site to another, and that some sites tend to have better steadier
> average skies because of a combination of altitude, topology, and
> proximity to other features that may disrupt laminar flow. My own
> experience has been that Bumpass Hell parking lot tends to have
> steadier skies than other sites around Mt. Lassen. In the Bay Area,
> both Mount Hamilton and Fremont Peak have had more consistently good
> seeing than the other sites I have tried.
>
> There was a pretty good example of this from just last Thursday night
> if you compare observing reports from observers at four different
> locations. (This is one of the reasons I enjoy reading observing
> reports on TAC- simultaneous experience collected from a range of
> locations).
>
> 1) Henry Coe (4/22/2004):
>
> "Star images were not crisp. Jupiter was swimming, though it offered a
> wonderful sight as
> always with its satellites." ---- William Schultz
>
> 2) Montebello (4/22/04):
>
> "The sky was good... seeing on the planets seemed good... I had saturn
> at about 240x mostly solid w/ occasional bluriness" ---Jeff Crilly
>
> 3) Courtyard/driveway on the east side of Morgan Hill (4/22/04)
>
> "Jupiter was initially doing the backstroke, but was definitely
> looking better as time went on. Although the initial seeing was
> pretty soft, it was still far from the worst I've ever experienced."
> ----Bob Czerwinski
>
> 4) SW lot of Fremont Peak (4/22/04) Two reports
>
> "The seeing was remarkably sharp throughout the breezy period until it
> calmed
> down by 10pm. Planetary detail was very good on Jupiter with many whit
> ovals
> following the GRS at mid-disk. .... I was able to split doubles as
> tight as 0.5 arc-sec and
> tries alpha Coma B. at 0.4 arc-sec. It didn't split but was a clean oblong
> airy disk shape with nice diffraction all around. " ----Peter Natscher
>
> "The wind disappeared and the seeing only got better as the night
> progressed."
> ---John Gleason
>
>
> That's just one night, but is a good example of how much seeing
> conditions can vary from site to site. It is also a good example of
> why I still often head to Fremont Peak when I am looking for altitude
> and steady skies in the Bay Area.
>
> --David Kingsley
Received on Mon Apr 26 15:23:33 2004