Serendipitous Observations

The recent lunar eclipse has come and gone. Like many other
observers, I went out to see what I could see from my location.
Unfortunately, my location on the Earth's surface placed me at a
distinct disadvantage. I was able to see only the last nine minutes
of the umbral phase of the eclipse.

It's very rare that I observe celestial objects as they are rising or
setting; but after doing so I've never regretted it. Under such
circumstances it's possible to see phenomena that are not otherwise
visible.

On this occasion I was treated to two phenomena of interest. First
was the observation of a full Moon, in partial eclipse, distinctly
flattened along its vertical axis by atmospheric refraction. Even
without an eclipse, this was worth observing.

The second phenomenon involved color. Fortunately I had chosen to use
a small, 102mm SCT that was relatively free from chromatic aberration.
(My 80mm, f/5 achromat was left inside!)

A thin, distinct ring of color hugged the lunar limb. The bottom
portion of the ring was red. On both sides of the Moon, as I observed
the ring progressively higher up, I was treated to a familiar sequence
of colors. In order, the colors we red, orange, yellow, green, and
blue.

For me, the highlight of this eclipse were the above mentioned colors,
not artifacts from a telescope, but the result of atmospheric
refraction.

As it turned out, my location on planet Earth wasn't all that bad
after all!
--
Bill
Celestial Journeys
http://cejour.blogspot.com

This reminds me of one night years ago when I was casually sitting out
on my lawn looking out over the open fields to my East with a pair of
11x80 binoculars. I saw a glow over the hill which forms my horizon,
and homed in on it to watch the moonrise. I wasn't expecting much, but
when the limb of the moon rose over the hill, it was outright shocking!
Even with the atmospheric distortion, the just past full moon looked
like a giant, three dimensional golf ball rising up behind the hill!
Hardly a scientific observation, but I've never forgotten it!
Marty

On Mon, 5 Mar 2007, (Marty) wrote:

This reminds me of one night years ago when I was casually sitting out
on my lawn looking out over the open fields to my East with a pair of
11x80 binoculars. I saw a glow over the hill which forms my horizon,
and homed in on it to watch the moonrise. I wasn't expecting much, but
when the limb of the moon rose over the hill, it was outright shocking!
Even with the atmospheric distortion, the just past full moon looked
like a giant, three dimensional golf ball rising up behind the hill!

One tends to remember such observations.

On one night I was anxious for a quarter moon to set so I could begin
some deep-sky observing; but the Earth wasn't rotating fast enough to
satisfy me. So, I pointed the telescope at the soon to be setting
moon. The large scale atmospheric turbulence appeared to move in
S-L-O-W motion -- creating another memorable observation.

On a different occasion I couldn't resist 'playing with' a new
apochromat refractor. A few nights earlier I had checked out Venus
(when relatively high in the sky) and noticed no false color; but on
this occasion Jupiter had just made its way above my horizon. I
pointed the scope at Jupiter and was greeted by a sight similar to the
one that started this thread: Adjacent to Jupiter's upper limb was a
blue glow, while the lower limb was adjacent to a red glow. It was
somehow satisfying to use a refractor to observe well-defined,
atmosphere induced, false color!

Now I'm reminded of another truly serendipitous observation: I was
observing Uranus (or was it Neptune?) one evening when I noticed a
'star' that showed some very obvious motion relative to the planet. It
didn't take long for me to realize that the 'moving star' was in
reality neither moving, nor a star. I had stumbled upon a
geosynchronous satellite!
--
Bill
Celestial Journeys
http://cejour.blogspot.com

but the Earth wasn't rotating fast enough
to satisfy me.

Gerald oughta be satisfied with this...
Now I'm reminded of another truly
serendipitous observation: I was
observing Uranus (or was it Neptune?)
one evening when I noticed a 'star' that
showed some very obvious motion
relative to the planet. It didn't take long
for me to realize that the 'moving star'
was in reality neither moving, nor a star.
I had stumbled upon a geosynchronous
satellite!

Cool! I've never (knowingly) seen one of those...
Marty

Marty wrote (about geosync sats):
Cool! I've never (knowingly) seen one of those...

The geostatationary satellites (a subclass of geosyncs that stay more or
less above the same spot on the Earth's equator) cluster around the
celestial equator, for what I hope is a reasonably obvious reason, so
looking just south of the equator if you're in the northern hemisphere,
or just north of it if you're in the southern hemisphere, will allow you
to pick one up eventually. I've seen a couple of them while observing
the Trapezium.

Puzzle: Estimate my latitude.

--
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.html

Brian Tung wrote:
Marty wrote (about geosync sats):
Cool! I've never (knowingly) seen one of those...

The geostatationary satellites (a subclass of geosyncs that stay more or
less above the same spot on the Earth's equator) cluster around the
celestial equator, for what I hope is a reasonably obvious reason, so
looking just south of the equator if you're in the northern hemisphere,
or just north of it if you're in the southern hemisphere, will allow you
to pick one up eventually. I've seen a couple of them while observing
the Trapezium.

Puzzle: Estimate my latitude.

Answer #1: google isi.edu, see that it's in Marina del Rey, CA =
latitude is about 33 degrees. ('Tis a shame Google Maps lacks lat/lon
grids....)

Answer #2: Geosynchronous radius is R = sqrt (GM/n^2), with
GM = 398600 km^3/s^2, n = 2pi/86164 radians/sec, so R = 42164 km.
Declination of the Trapezium is -5.4 degrees. I'm not going to
try an ASCII plot, but it's obvious that
tan Dec = -r sin lat / (R - r cos lat)
with r = Earth's radius (assuming a sphere) = 6378.14 km.
The solution is
lat = Dec - arcsin (R sin Dec / r)
= +33.07 degrees.

Thanks for giving me a little bit of fun this evening.

-- Bill Owen

P.S. I've seen a geostationary satellite show up in my pictures too.
Nice straight line running e-w, and if you take the same field one
sidereal day later, it'll still be there. Perplexed the heck out of
me until we figured out what it was.

Puzzle: Estimate my latitude.

Brian, you overestimate my intelligence by several magnitudes. However,
playing with a globe, a ruler, the Scalnate Pleso Atlas, and a trig site
on the internet, (I don't know trig...) and hopefully remembering the
distance of the geostationary satellites as 22,000 miles, I'd crudely
guesstimate around 35 degrees...??
Marty

The solution is
lat = Dec - arcsin (R sin Dec / r)
= +33.07 degrees.

Bill,

I get that but only after dropping the sign in sin Dec.
Isn't that a trigonometric sin?

Ben

On Mar 6, 9:03 pm, (Marty) wrote:
Puzzle: Estimate my latitude.

Brian, you overestimate my intelligence by several magnitudes. However,
playing with a globe, a ruler, the Scalnate Pleso Atlas, ....

You got a Skalnate Pleso Atlas? !!! Where on Earth did you
get it? I looked for one for the longest time and came up zilch.

Ben

You got a Skalnate Pleso Atlas? !!! *
Where on Earth did you get it? I looked
for one for the longest time and came
up zilch.
Ben

I bought it when it was new.
Marty