What’s California doing in space? Drifting through the Orion Arm of the spiral Milky Way Galaxy, this cosmic cloud by chance echoes the outline of California on the west coast of the United States. Our own Sun also lies within the Milky Way’s Orion Arm, only about 1,500 light-years from the California Nebula. Also known as NGC 1499, the classic emission nebula is around 100 light-years long. On the featured image, the most prominent glow of the California Nebula is the red light characteristic of hydrogen atoms recombining with long lost electrons, stripped away (ionized) by energetic starlight. The star most likely providing the energetic starlight that ionizes much of the nebular gas is the bright, hot, bluish Xi Persei just to the right of the nebula. A regular target for astrophotographers, the California Nebula can be spotted with a wide-field telescope under a dark sky toward the constellation of Perseus, not far from the Pleiades. (From APOD)
A test shot from my backyard at Sunnyvale, CA to test ATR8 reducer on AT111EDT.
Overall star shapes look fine across entire field, though at corners the stars are not round, and some even have weird shapes, which might have something to do with focus and tilt of focuser and 2″ EP connector.
Another note is that bright stars in L frame are much larger (and have bigger halos around them), so LRGB combination not only brings out many faint stars, it also makes bright stars much bigger, which swamps the center area of both clusters. To mitigate the issue, I generate a star mask of only small stars in L frame and apply it to RGB frame, the halo issue of bright stars get resolved and it does not affect faint stars either.
Date: 10/25/2017, 10/27/2017, 10/28/2017
Location: Sunnyvale, CA
Condition: Excellent transparency, Excellent seeing, light dew
Exposure: Ha – 29x900s
Telescope: Astronomics AT111EDT + ATR8 reducer
CCD: SBIG STF8300M + Baader LRGBHaO3S2 filter