[Chaos-l] Observing Report From Medoc Mountain

[E. Allen Davis]

Thanks Robert for the report....it is nice to read this and go back over our observing for the evening.  The skies were generous to us for a while, and I certainly enjoyed the company.  All in all a SWELL few hours.allen


----- Original Message -----
From: "Robert Nielsen" <robertnielsen at nc.rr.com>
To: "Chapel Hill Astronomical Observation Society" <chaos-l at rtpnet.org>
Sent: Sunday, January 25, 2009 8:55:31 PM GMT -05:00 US/Canada Eastern
Subject: Observing Report From Medoc Mountain

Well, you might not believe this ... but there was a useful observing 
session at Medoc Mountain State Park last night.  I was there, along 
with Mark Lerch (from CHAOS) as well as Allen Davis (camped next to us 
at MASP) and two of Allen's friends - Tim and Don.   I got there a 
little early to setup my Mewlon in the daylight ... and yes, the skies 
were completely covered in clouds at the time (although during the drive 
over from Astronomy Days I could see breaks in the clouds).   Allen 
setup his 20" Obsession, Tim had some binoculars on a parallelogram 
mount, and Mark had his "minimalist" astrophotography setup with the 
AstroTrac.

It was a little odd setting up under the clouds, and taking on faith 
that the Clear Sky Clock was correct and that things would clear up ... 
but they did indeed ... actually an hour earlier than expected.   So we 
all got in some early observing starting around 7PM.   Then the wind 
changed and some clouds rolled in from the east.   While things clouded 
over, we sat under a picnic pavilion and enjoyed a fire provided by 
Allen.   In some ways, Medoc Mountain is a *more comfortable" place to 
observe since it has (heated) restrooms, a fireplace, etc. than other 
places we have gone.  Too bad it is 1.5 hours away!

Before the clouds rolled in, I had polar aligned my telescope, and took 
a quick look at M42 (to see how the skies were).  As predicted by the 
Clear Sky Clock, the transparency was very good ... although the seeing 
was not the best (more on that later).  I could pretty easily make out 
the fifth Trapezium star ... and the sixth flickered in and out.  But 
since the transparency was good, I decided to focus on the galaxies that 
I had chosen for the nights targets.

First up was NGC2403 ... a spiral galaxy in Camelopardalis that looks a 
lot like a miniature M33 (faint, face-on, with bright area that I think 
are star-forming regions).   It was faintly visible with the bright 
spots looking like little diamonds in the area of the galaxy.  It is 
framed nicely by two brighter stars on the two sides of the galaxy.   I 
was impressed by how much detail was visible with direct (not averted) 
vision.   I was also impressed with the skies at Medoc Mountain ... 
since I stayed almost the entire night at 225X while looking at all the 
galaxies in the northern sky.

I also checked out NGC2655, which was listed in some observation lists 
as "the western member of a pair of galaxies".  Well, 2655 was easily 
visible, but it's partner was much much fainter.   It was a nice galaxy 
viewed from the side (not really edge on) but it's partner was just a 
smudge.  I then moved to NGC1501, which is a planetary nebula also in 
Camelopardalis.   Very nice, with a easily visible central star.  That 
was the last thing I was viewing when the clouds rolled in ... and when 
the clouds cleared 40 minutes later, I could tell the mount was well 
aligned ... it hadn't moved at all in the field of view.

One of the nice things last night was that I could compare views through 
my scope with views through Allen's Obsession.   The first object we 
compared was NGC2403, and that started Allen on a tour of (as he put it) 
"10th magnitude galaxies in the northern sky".  By the fire, we 
discussed how amazing it was that his scope, built of wood and assembled 
with struts and collimated earlier, was able to locate objects (using 
the Argo Navis) and provide views that were that amazing.   It is 
amazing when you think about it.

After the clouds cleared, we branched out.   Actually, at this point, I 
think I should publicly thank Mark Lerch for appeasing the astronomy 
gods and providing the clear skies because during the cloud cover, he 
decided it looked bad and had packed up his gear (a sure way to cause 
the skies to clear).   I guess that's a side-effect of the difference in 
our gear.  His is so light and easy to setup (and take down) that you 
can make decisions quickly.  I, on the other hand, didn't want to take 
my gear apart and I waited (and hoped) things would get better.   But 
I'm glad to know that Mark got at least one good shot during the night.

But under the new clear skies, I borrowed Allen's hydrogen-beta filter 
and tried once again to see the Horsehead Nebula through my scope.  Some 
of you may remember from MASP that Allen let Michael Hrivnak and I 
borrow the filter, and we both tried to see the Horsehead ... Michael 
with immediate success ... but nothing but frustration for me.   
Admittedly, I have 12-inches of aperature, compared to Michael's 18 and 
Allen's 20 ... but Allen thought I would be able to see it in my 
scope.   Well, after MASP I researched Hb filters and found some 
interesting articles on the filter and *exit pupils*.   The summary of 
the articles I read was that because the Horsehead is so faint, you need 
an exit pupil of at least 5mm to see it optimally.   Well, the exit 
pupil is calculated by dividing the eyepiece focal length by the 
telescope's focal ratio.   Allen's and Michael's telescopes?  Both 
around f/4 or f/5.  Mine?  f/11.9!!!!  So to get to that point, you need 
a long eyepiece.   I hadn't tried that at MASP (since I didn't know ... 
sorry to Jim Pressley who explained this to us once at a CHAOS meeting) 
since I didn't own an eyepiece long enough.  Now I have a 55mm Plossl.   
The exit pupil for this eyepiece in my scope?   55/11.9 or 4.62.   Not 
optimal ... but close.

And yes, it was close.   Both Allen and I could ... when your eyes were 
dark adapted ... and you stared long enough to get good conditions ... 
just barely see it.  In Allen's Obsession ... no problem.   I guess I'm 
just not going to be able to see that object well in my Mewlon.   But 
galaxies and planetary nebulae ... it is really great!

Which is why I switched to the Eskimo Nebula next.   My scope does a 
really, really good job of viewing it.  You could definitely see the 
radial spikes in the "fur".   And the skies allowed me to push the 
magnification to 400X.   About that time, Allen had the Rosette Nebula 
in his obsession, with a very nice German widefield eyepiece.   Again, 
the skies allowed the nebula itself to be wonderfully bright, with lots 
of structure.   Couldn't get it all in one field of view ... but it was 
great shifting the view and looking at all the complexity of that nebula.

While Allen and I were hunting galaxies and nebulae, Tim was searching 
the skies around Canis Major for clusters, including M46 (the open 
cluster with the embedded planetary).   I tried looking at the Perseus A 
Galaxy Cluster (which was amazing at MASP) and I could see NGC1725 
clearly ... but the other galaxies were a little dim.  I probably waited 
a little too long ... and Perseus was getting low in the sky.   With 
Perseus low, Leo was getting higher in the sky, and that meant Saturn 
was visible.   I was really looking forward to seeing Saturn in my 
scope, which is supposed to be good for planets, but I had forgotten 
about the seeing conditions ... and sure enough, Saturn was wobbly.   It 
was an interesting sight ... with just *lines* sticking out of each side 
(since the rings are almost edge-on) but it never settled down.  In 
fact, at 2 AM when Allen and I were getting ready to leave, we took one 
last look at it higher in the sky.  Still wobbly.   I need to wait for a 
better night, with better seeing.

Before it set, we looked at Hind's Crimson Star (R Leporis) which was 
bright orange.   And before we left, Allen looked at a couple of objects 
rising in the east.   M51 (Whirlpool) was about the best I had seen it 
in a long while.  With direct vision, you could see the arms clearly in 
the larger galaxy of the pair, and definitely some structure even in the 
smaller galaxy.   Allen got NGC4565 (a nice edge-on in Coma Berenices) 
in his scope, and it was beautiful.   And we looked at M3, one of my 
favorites.  It was a little low in the sky, but still beautiful.   Can 
you tell I was having fun?

I was debating whether to stay after Allen left, but decided I needed to 
get back ... which was a good thing since I started seeing more and more 
clouds as I drove back to Chapel Hill.  So it was just a matter of time 
before it got to Medoc Mountain.   But still, it was an amazing night, 
especially considering the clouds and rain and such that has been 
happening recently.   I hope next time that everyone can join us over there!

Sorry for the long post, but a lot happened.   I'm really happy I 
went!   Moral of the story: trust the Clear Sky Clock!

Robert