Wednesday, February 11, 2015

A Wide-Angle Kinda' Night!

When we were on our Whitewater Draw excursion last weekend, I was thinking of taking advantage of some of the pristine skies in the area to shoot the Zodiacal Light, which is currently very prominent in the evening sky. But after hours of driving and bird watching, we decided heading for home.

So on Monday, even though I initially had plans to attend the astro-imaging SIG (Special Interest Group) to hear buddy George Hatfield about DSLR imaging, the siren call of the clear blue sky called me to fight rush hour traffic and head west towards dark sky. My destination was one of the upper overlooks on the Kitt Peak access road with an excellent vantage point to observe the western sky. Melinda joined me for the trip, arriving just a little after sunset.

Interestingly, the calm air in Tucson gave way to nearly 30mph winds at 6,000 feet elevation.  It wasn't cold, low 60s, but the wind was just howling!  I set up the tripod and tracking mount for taking some wide-field shots of the Zodiacal Light, but was called from my set-up duties by the constantly-changing views as it darkened.  At left, the golden glow of sunset was transitioning to crimson as the lights of Sells, the capital of the Tohono O'odham reservation became visible.  I used the Canon 70-200 zoom at 140mm for the 2-frame mosaic shown.  And at right, the view of Orion rising over the slopes of Kitt Peak above us were too scenic to overlook.  Even though just a 30 second exposure with a 14mm (Samyang, F/2.8), it caught the remaining light illuminating the hills, yet shows the Winter Milky Way and a pair of crossing satellites when clicking to load the full-size image.

It wasn't long till the Zodiacal Light became visible. It is caused by dust from asteroid collisions in the plane of the Solar System.  In the northern hemisphere, it is prominent this time of year because it stands nearly straight up from the horizon. While described in the link as "faint", near the sun it is certainly brighter than the remnants of the Summer Milky Way still above the horizon in the Northwest. The image at left is from an ultra-wide shot from an 8mm fisheye, that shows both the Zodiacal Light and Milky Way. From a dark sky location like Kitt Peak, it reaches clear up to the zenith splitting the star clusters the Hyades and Pleiades. Realize this is only an 80 second (!) exposure with the tripod-mounted canon 20Da and 6mm fisheye at F/2.8...

With the other camera (Canon XSi) and Samyang 14mm, stopped down to F/4, I was using the Polarie tracking mount to take 140s exposures, moving up from horizon to zenith, in hopes of doing a multiple frame high-resolution mosaic. They all looked good on the back of the camera, so had high hopes. The image shown here at left was assembled using Microsoft ICE (Image Composite Editor), before further manipulation in Photoshop.  Evidently they have a new version, but I'm still using the initial version. I'm constantly amazed by what this freeware program can do, aligning to star patterns! Photoshop gives up right away, so am constantly glad that ICE is a consistent tool. I was going through the frame carefully in order to label the brighter objects and constellations, and didn't see any missing stars or additional ones either, so did a great job. The image at left (and right with labels) are at the maximum image size I can show (1600 pixels tall), so be sure to click it to examine closely. Besides some good galaxies and clusters, Comet Lovejoy is still visible as a greenish smudge, and Uranus is smack in the middle of the Zodiacal Light with Mars and Venus.

While completing the above series of exposures, I even had time to shoot a self-portrait with the 8mm fisheye with the new van and Winter Milky Way high in the background. It is only a single exposure (80 seconds at F/2.8 and ISO 1600) on the non-tracked image, so is a little noisy, but still sensitive enough to see Milky Way, and even the upper tip of the Zodiacal Light to the right of Pleiades high in the frame. I had promised Melinda we'd return early, so with a few minutes to go after finishing the above sequence, I installed the 80mm lens at F/2.8 to take some pictures of Orion's belt. Shown at right is a stack of 6 exposures of 80 seconds each (8 minutes total).  Imagine an observing session when I actually had time to spend an hour or two on a field, instead of minutes.

Fortunately, with the blustery wind, I was able to get some good images out of the session.  I ended the imaging right at 9pm, and only missed our estimated 10pm return home by 15 minutes.  The little tracker and tripod shots survived the wind just fine - helped by the wide-angle shots taken that night.  Since we got home by "curfew" I should think more about these mini-sessions...

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