Sunday, August 28, 2016

Appulse Day!

Finally! Appulse Day has come and passed! You won't have to sit thru another blog post about the upcoming conjunction in the west till the next one rolls around! From Arizona it was great - not a cloud in the sky for much of the day - the monsoons are winding down, the temps have dropped below 100F and all is right with the world!

Besides visiting sis-in-law Maj, our friend Donna came down for the weekend from Phoenix, so left them instructions for viewing from our cul-de-sac and left Melinda in their capable hands to go observe the western horizon. Kitt Peak's profile has served as backdrop for a number of photo projects, from Solstice Sunsets to other conjunctions over one of the largest collections of professional observatories. The conjunction occurred almost due west, so found a spot about .6 miles south of milepost 37 on the Sasabe road for the perfect alignment. I arrived with a brilliant sun still up and it was uncomfortably warm till it sank below the level of the Coyote Mountains. The view at left shows sunlight streaming between the 4 mile separation of Coyote and Quinlan Mountains where Kitt Peak is located. Clear with a little haze in the air - visible when lit by that brilliant sun.

Well before the real sunset, I was anticipating trying to get a close-up view of the planets. I used the same setup put together to image the International Space Station earlier in the year - I used the XSi camera (APS sensor) with the TEC 140 along with a 2X Barlow to get a nice image scale with a minimum of blurring. While the combo worked for some images of the planets, moons and Observatory profile, I was afraid the twilight would be too dark at F/14 for video, so only used it for some images well before the planet-set. Shown here at left is the result of a 3-image stack to increase the signal for 1/2 second exposures. I didn't track, so exposures of the ultra-long focal length (at least about 2 meters) had to be under that magic number to prevent blurring from Earth's rotation to be objectionable... Still, I'm thinking the distortions of the atmosphere at low elevations were the major contributions of any unsharpness. Also visible is the atmospheric dispersion from the ocean of air overhead. At low elevations, due to the curvature of the earth the atmosphere acts like a prism dispersing light into a rainbow. Note the planets have a reddish lower limb and a blue-green upper edge caused by this effect. At right is a labeled version of the same image with the moons of Jupiter identified...

Before it had gotten too dark, I used the same setup to image the mountaintop as well. While I collected a full profile set to make a panorama, shown here at left is the part of the mountain where the planets later set. from left, the domes visible are the Burrell Schmidt of Case Western Reserve University, and right of the communications microwave tower are the UA's telescopes, the 1.8 meter and 36" Spacewatch telescopes, and at far right the flat-topped dome of the Bok Telescope, 2.3 meters diameter. As you will see in the video, both planets ended up disappearing behind the 1.8 meter Spacewatch Telescope. The combination of long focal length and 12 miles distance preserved pretty good detail at the Observatory. There are tricks to taking as sharp of images at possible though. With the nearly 2 meter focal length of the TEC plus 2X Barlow, I enabled mirror lockup in the camera, which moved out of the way when the shutter button was pushed. Then I enabled a 2-second delay to wait for vibrations to die down before the shutter was released. As a result you can easily see some details just a few inches across - not bad from 12 miles!

As the planets sank lower, I looked for Mercury, the third and least-mentioned addition to the party and spotted it briefly in binos. It is getting fainter, and hugging the horizon like it does here in the northern hemisphere I wasn't sure it could be recorded. I took a snapshot, shown here cropped from a 200mm shot with the XSi at 1/8 second. Not obvious, but can barely be seen in the full-size image if you click on it. Still not see it - well, check out the right image where it is labeled! Waiting for the sky to get darker doesn't work as it set a minute later... This one was stretched and cropped carefully to pull it out of the twilight.

With Mercury out of the picture, it was showtime! I set up the 300mm lens with Melinda's T1i camera for a wide-field shot - it does a good job of recording the scene as it appeared by eye or a little optical aid like binoculars. Unfortunately at this scale it shows some hints of the moons of Jupiter, the lower right of the pair, but doesn't resolve them well. Still, a nice view of the jewels hanging over the Observatory.

On the "big" scope (the TEC 140), I mounted the Canon 6D that had video capability. Since I had been recording the planets and mountain profile with the scope above, I didn't have time to change out the 2" adaptor to the field flattener and low-vignetting adaptor, so both here and in the video there is vignetting (darkening in the corners) from the 2" accessories blocking part of the image for the larger sensor. The image at right was taken just before starting the video, and clearly shows Jupiter's moons clearly resolved in the 30th of a second exposure (ISO 6400!). Similarly the video should have the same resolution, but is clearly degraded below.

Anyway, if you can tolerate a few minutes of my monotone narration, check out the video below. I did this live, so you get the full effect of the border patrol trucks zipping past my location, and catch me on a least 2 occasions calling "Venus" "Saturn"! In the meantime, there aren't any big events coming up on the horizon, so you will be spared my harping on you to get out and observe. I hope you checked it out - the girls at home enjoyed the view from the cul-de-sac, I hope you enjoyed it as well from your location!

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