Cassiopeia Observatory logo

NGC6888 (Crescent Nebula) HA OIII

Posted: 17 September 2022

On Friday, 16 September 2022, I posted a special announcement on Facebook:

Open: Friday, 16 September 2022, 1809 MST
Temperature: 80°F
Session: 1789
Conditions: Clear

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
Filter Slider System
2" H-Alpha filter
2" OIII filter


1816 MST: Dome OFF.

1826-1900 MST: Relaxed on the observatory patio bench.

1830 MST: Sunset.

1902 MST: LX600 ON, StarLock OFF, High Precision OFF.

Viewed Saturn, 102X.

1907 MST: Relaxed on the bench to watch the stars come out.

1935 MST: Back in the observatory. Prepared the D850 DSLR for imaging NGC6888 (Crescent Nebula). Since I would be imaging using the Optolong H-Alpha and OIII filters, I used the Starizona Filter Slider System to mount the D850 DSLR at prime focus. Focused on the star Deneb and locked the 12" primary mirror.

1950 MST: High Precision ON.

Slewed to NGC6888 (Crescent Nebula).

1952 MST: StarLock ON.

I took six StarLock autoguided images using the HA filter (5 minutes, ISO 3200) and six with the OIII filter (ISO 6400, 5 minutes). When switching filters I refocused on Deneb. Here is one of each filter image (edited) and the stacked result for each filter (using Affinity Photo).

H-Alpha stacked

O-III stacked

This is a merge of the two stacked images using Adobe Photoshop.


2121 MST: StarLock OFF, High Precision OFF.

Removed the camera and Filter Slider System. Viewed NGC6888 (Crescent Nebula), 102X. Then viewed Jupiter, 102X.

2133 MST: LX600 OFF.

2137 MST: Dome ON.

2143 MST: Took a Sky Quality reading.

Close: Friday, 16 September 2022, 2146 MST
Temperature: 68°F
Session Length: 3h 37m
Conditions: Clear, SQM 20.96

Comments are welcome using Email. Twitter users can use the button below to tweet this report to their followers. Thanks.

Previous report

Cassiopeia Observatory Home Page

Back to Top

Copyright ©2022 Michael L. Weasner / Email Etiquette.