[AZ-Observing] Thanksgiving Sky
- From: Andrew Cooper <acooper@xxxxxxxxx>
- To: TAAA Forum <taaaforum@xxxxxxxxxxxxxxx>, AZ-Observing <az-observing@xxxxxxxxxxxxx>
- Date: Thu, 23 Nov 2006 20:11:44 -0700
Sometimes you just need someone to give you an excuse.
Some time ago I had answered some questions about observing sites around
Tucson for a fellow amateur visiting the Tucson area. Now actually here
Renato del Rosario asked if anyone would like to join him for a night
out. As life had conspired to keep me from observing the previous
weekend I was more than amenable to a night out. I was not alone, Sam
Rua was also looking for an excuse to get out and Renato offered just
such an excuse.
Read on or read full article
<http://www.siowl.com/index.html?thanksgiving> complete with photos and
the animation.
The proposal was made to head for Las Cienegas, always a beautiful site,
an entire broad valley free of lights with desert mountains on the east
and western horizon. Better with a group as there is some concern about
illegal immigrant traffic in the area. Plans were made, a rendezvous set
and we caravanned together out to the site.
A few cirrus clouds concerned us as the sun set. But these only served
to make the sunset more dramatic as they dissipated or passed to our
north. This left us with a beautiful Arizona sky for the rest of the
night. Seeing wasn't to sharp, maybe a 6 or 7 most of the night, and
transparency suffered from a little dust, giving us a magnitude 6 sky,
maybe a little better. No complaints, as I sit here the next day writing
this it is nearly completely overcast, sometimes the weather gods smile.
As the sky darkened I sat beside the scope and contemplated the beauty
of the scene. The thin moon setting over the rugged profile of the Santa
Rita Mts. and beauty of the Summer Milky Way through Aquila, Cygnus and
Cassiopea. Just what I come out into the Arizona desert for. Then the
cell phone rings... fortunately, or unfortunately depending on your
point of view, there is good cell coverage of the Las Cienegas site. Yes
dear, everything is fine, yes I will remember to bring home a gallon of
milk for Thanksgiving, Love you. A moment later the phone chirps again,
a text message "remember milk..." She knows me far too well.
Observing as a group offers many advantages, company, sharing as well
additional security. How many times have I had an observing session
saved when something forgotten was supplied by an observing buddy. A
bolt, cable, battery, or all of the little details than can cause
trouble at the wrong end of an hour's drive. This night we swapped gear.
Sam realized he had forgotten a Telrad, I lent him mine once I had
gotten the digital setting circles aligned. Later in the night I
borrowed a 2" Hydrogen beta filter. With mutual support the night
proceeded smoothly.
Early in the evening I setup the Canon 20Da on the eastern horizon with
a wide angle lens. With a timer set for a 1 minute exposure every three
minutes I hoped to gather the material for an animation of Orion rising.
This worked pretty well, even with having to shoot a bunch of test
images attempting to balance exposure length while minimizing the
trailing for the stars. The finished result can be seen below.
The observing list was a number of objects that I had added to my
observing database but had no observations for. Just a smattering of
stuff I had never before observed and a few random selections from the
Night Sky Guide. This was between looking at a few objects in Either
Sam's scope or Renato's, or just sitting back watching the meteors that
streaked the night.
The real surprise of the night was NGC2359, also known as Gum 4 or
Thor's Helmet. This great nebula is in Canis Major, a really spectacular
object with a very visible Wolf-Rayet sphere. With an OIII filter the WR
structure showed a sharp outer shell and several filaments. It was even
better in Sam's 25" where the spherical structure showed even more
detail as well as structure in the surrounding dimmer nebulosity.
A few selected observations of the night...
IC410 Very faint but distinct nebula laced through the moderately rich
open cluster NGC1893, an irregular glow most noticeable in the cluster
and just west of the cluster, UHC filter necessary
IC417 Extremely fain nebula through a bright thicket of stars just south
of M38 and NGC1907, edge of nebula most evident on the north edge
towards the clusters where the background becomes noticeably darker
NGC2359 Large, bright nebula with a complex structure, visible as a
large glowing patch without the filter, with the OIII filter the
structure becomes far more interesting, a circular structure dominates
the north side, a hard brighter northern edge and a filament just inside
this emphasize the spherical nature of the structure, a bright
protrusion is on the south edge and continues west, there is extensive
dimmer structure surrounding the sphere, particularly to the north and
east, with Sam Rua's 25" even this extended exhibits structure with a
few knots and filaments, rich winter Milky Way starfield
NGC1990 Very faint and extensive nebula centered on Epsilon Ori, best
detected by panning though the field and noting brightness changes in
the background, looking straight at Epsilon the background is clearly
not very dark at the center of the nebula
NGC 2023 A bright reflection nebula surrounding the 7.8th magnitude star
HD37903, round with no other detail, about 10' across, just off the edge
of IC434 and the Horsehead B33
Trumpler 6 Modest open cluster in a rich Milky Way starfield, distinct
cluster well detached, reasonably rich a good population of dimmer
members around a few brighter members, about 5' across, fairly round.
Dawn was beginning and Mercury rising in the east when I broke down for
the run back to Tucson. And I didn't forget the milk.
Andrew
Andrew Cooper
----------------------------------------------------
http://www.siowl.com
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