[AZ-Observing] I Found An Elephant Last Night...
- From: "David M. Douglass" <dmdouglass@xxxxxxxxxxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Mon, 21 Jul 2014 11:11:44 -0700
Well, at least his “trunk”… (IC 1396 – The Elephant Trunk)
[... I realize that we have an ongoing discussion regarding links to images.
I do not post most of my images, trying not to "clutter" the email boxes. I try
and save the posts to the unusual ones, or special ones (for whatever reason).
I really love the Large FOV nebulae, especially in Ha. All reply comments are
welcome, but in the interest of keeping the peace, please send them to me
"offline" at my email address, shown above, or below in my signature. Thank
You. ...]
Actually, I have noticed recently that most people just image the “trunk” area.
I wonder how many people realize that actual “object” structure is much larger.
IC 1396 is cataloged at 170x170 ArcMin. This is just short of 3 Degrees square.
That is a Large FOV. In this case, my image is a composite of four (4) separate
images (a Mosaic), taken with my wide field of view (FOV) 80mm telescope. Each
frame of the four is a stack of 3 20-min exposures, using a Ha filter. Total
capture time is about 4.5 hours. You can see it here, if you wish:
http://www.az-dahut.net/Obs-Log-Sheets/IC-1396-07202014.jpg
The Astronomical League program “Bright Nebulae” contains so many beautiful
objects to view and enjoy. And so many “critters”……
We in the Astronomy hobby are so fortunate to be able to observe, and capture
images of these fantastic objects. It is hard to realize that probably 90% or
more of the masses (people) never get a chance to see either the actual object
(visual), or, as in this case, a locally captured image of them.
The real challenge to many, as I read in the various forums, are these Large
FOV items. They are difficult to “view” in a single FOV. The best method seems
to be imaging, and that requires multiple frames, and a method to create the
“mosaic”. Although named “Bright Nebulae”, the list (about 130 items) is
mostly a collection of very dim objects. This one (The Elephant Trunk) is
pretty bright (in Ha). But there are so many that are dim dim dim. Trying to
capture them with the camera, even with 20 minute exposures, is sometimes just
on the edge of possible.
David M. Douglass
dmdouglass@xxxxxxxxxxxxxxx (secondary)
david@xxxxxxxxxxxxxxx (main)
Cell (602) 908-9092
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