DSLR Imaging: Nebulae, Uranus Moons
Posted: 23 November 2016
Saturday, 19 November 2016, dawned clear but windy. Clouds from an approaching storm system arrived mid-day. Sunday morning, 20 November, I was briefly in the observatory for some testing of a new version of the "ScopeBoss" AutoStar handcontroller iOS app for the developer. Didn't need a clear sky for the tests; didn't even open the observatory dome. Received 0.02" rain by the end of Sunday, and then 0.45" on Monday, 21 November. Tuesday, 22 November, dawned clear. Went to the observatory mid-morning to do more ScopeBoss tests.
Open: Tuesday, 22 November 2016, 1805 MST
Conditions: Mostly clear
1810 MST: LX600 ON, StarLock OFF, High Precision OFF.
1813 MST: viewed Venus and Mars, 102X.
Then began preparing for 12" telescope prime focus imaging of several nebulae using the D7200 DSLR. 1830 MST: mounted the DSLR at prime focus. Focused on the star Fomalhaut using a mask. Locked the focus with the mirror lock bolt.
1842 MST: StarLock ON for autoguiding. Seeing was apparently not very good at the location of the object as I frequently saw StarLock guiding statuses of >10 in Right Ascension and Declination, regardless of the StarLock guiding rate percentages I set. Greater than 2 is not good. The best image of Abell 70 is this one, 1 minute, ISO 6400, White Balance 4000K, cropped from the full-frame image:
The streak is a bright satellite that passed through the field-of-view. The planetary nebula is at the center. The bright object at the top of the nebula is actually a distant galaxy (PGC187663). I will try again to image this neat object next year when it is better placed for imaging.
1902 MST: Wi-Fi OFF. High Precision ON.
Slewed to NGC7008 (planetary nebula). Guiding rates were better here (StarLock guiding rate percentages were set to 66%). This is a 2 minutes, ISO 6400, White Balance 4000K, image, cropped from the full-frame image:
1942 MST: some breezes were picking up. Had some difficulty with High Precision pointing. Ended up turning High Precision OFF for the remainder of the session. Also, had some difficulty getting the mirror lock bolt tight enough to prevent mirror movement during slews, which would change the image focus. With HP OFF and StarLock autoguiding ON, I managed to get these images, all cropped from the full-frame image:
NGC1514 (planetary nebula), 2 minutes, ISO 6400, White Balance 4000K
NGC1333 (nebula), 5 minutes, ISO 6400, White Balance 4000K
NGC1491 (nebula), 5 minutes, ISO 6400, White Balance 4000K
NGC7662 (Blue Snowball, planetary nebula), 1 minute, ISO 2500, White Balance 4000K
I'm not happy with the Blue Snowball image, so will re-image it on a future session.
2047 MST: ended Deep Sky Object (DSO) imaging. StarLock OFF.
Slewed the planet Uranus. Took this 5 seconds, ISO 5000, WB 4000K image (cropped) showing four of the planet's moons:
2057 MST: ended imaging.
Viewed NGC253 (Sculptor Galaxy), 102X. Nice view of this large galaxy. SYNCed on the galaxy. Will image it on the next session. 2110 MST: LX600 OFF.
Close: Tuesday, 22 November 2016, 2122 MST
Session Length: 3h 17m|
Conditions: Clear, breezy
Check out this TODAY Show video: "A Colorado town goes dark to let the Milky Way shine bright".
Digital camera astrophotographers may want to check out this article: What is the Best ISO for your DSLR for Astrophotography?. I've tried using lower ISO values in the past but was never as satisfied with the results as I was with some higher values. But then I'm a lazy astrophotographer who does not want to spend hours stacking and editing many short exposures of faint objects. As I've said many times in the past, I just play at doing astrophotography.
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