Cassiopeia Observatory

Lunar Terminator Sunrise Video

Posted: 28 October 2012

Cassiopeia Observatory was opened Saturday, 27 October 2012, at 1745 MST, 76°F, clear sky. At 1752 MST, viewed the moon, low in the east, 77X. Switched from the star diagonal to the visual back and mounted the iPhone 4 to the 8" LX200-ACF using the MX-1 afocal adapter. Then took this photo (cropped), 77X:

While the iPhone was on the 8" telescope, I took this photograph of the telescope, the moon in the sky (overexposed), and the moon's live image on the iPhone screen:

I began lunar observing, 206X, at 1816 MST. Seeing was better this night than it had been on the last few nights. The southern end of this night's terminator was fascinating to view, with lots of foreshortened details visible. I switched to 364X, which provided nice views, but the best view of what I wanted to see as the sun rose was at 206X.

At 1835 MST, I began setting up for eyepiece projection (222X) imaging of the moon using the D7000 DSLR. I wanted to try a test and do a HD video recording of sunrise along the terminator. I selected Grimaldi and the surrounding area as the most likely to show a nice sunrise during a 20 minute recording. This "Hat Trick" single exposure, ISO 500, shows Grimaldi (mostly in shadow) just right of center:

I then did a short test video, followed by a 20 minute HD video, 1/250sec, ISO 5000. I processed the video in iMovie and time-compressed the 20 minutes to 29 seconds. Click the image below to see the video. The most noticeable affect of sunrise is the change of three small peaks near the center of the video (left of Grimaldi) being illuminated as the sun rose higher.

I plan to repeat the experiment on a future session when the terminator is well positioned to show rapid changes.

I removed the eyepiece projection adapter, added the focal reducer, and took this 1/500sec, ISO 100, prime focus image (cropped):

Ended imaging at 1923 MST. Removed the camera, focal reducer, and visual back, and switched to using the diagonal for some more lunar observing, 206X. I monitored sunrise at Grimaldi. At 1941 MST, I viewed the waxing gibbous moon through 7x50 binoculars. Very bright! At 1943 MST, I did lunar observing at 77X using a moon filter. The moon filter made the view easy on the eye.

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