Io Shadow Transit, M104 Sombrero Galaxy Tests
Posted: 12 May 2015
After two nice clear nights, clouds returned on Monday, 11 May 2015. But about an hour after sunset the sky had mostly cleared.
Open: Monday, 11 May 2015, 1935 MST
Conditions: Mostly clear
1942 MST: viewed Venus, then Mercury, 83X. Next, viewed Jupiter. Three moons were visible: Europa, Callisto, and Ganymede. Switched to the Baader 8-24mm Zoom Eyepiece to try to pick up Io, which was in transit. Unsuccessful. Added the Televue 2X PowerMate. The view at 333X was pretty good, but still no luck seeing Io.
2042 MST: Io's shadow began its transit of the planet. I mounted the D7200 DSLR at prime focus + 2X PowerMate, did a focus test on the star Regulus using the Bahtinov Mask. This is a stack of 1839 frames from the HD video, 1.3X crop factor, 60 fps, 1/100sec, ISO 2000, showing Io's shadow at the right between the equatorial cloud bands:
2102 MST: removed the camera and took a last look at Jupiter, 166X. Still could not pick up Io in transit.
Began setting up to do some imaging tests of M104 (Sombrero Galaxy). Added the Antares f/6.3 focal reducer and mounted the D7200 DSLR at prime focus. Did a focus test on the star Spica with the Bahtinov Mask. I then did 10 1 minute, unguided exposures of M104 at ISO settings from 3200 to 25600. During post-processing I tried merging the images using Photoshop to see how well the galaxy would show. That test didn't work out and didn't improve the image. This single full-frame ISO 12800 image shows M104:
2137 MST: getting breezy.
I also did 10 unguided 1 minute ISO 6400 exposures of M104. During post-processing I stacked the 10 images using Lynkeos, for this effective 10 minute exposure:
This resulted in a better image, but still need longer exposures (or higher ISO) to best capture the galaxy. Will do more tests on the next session.
2152 MST: ended imaging. 2159 MST: viewed M104, 83X. Then viewed Saturn, 83X, low in the southeast. The view was not very good this night.
Close: Monday, 11 May 2015, 2210 MST
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