Cassiopeia Observatory logo

Moon, Crab Nebula (UHC, OIII, HA filters)

Posted: 15 February 2021

Friday, 12 February 2021, was cloudy. Early Sunday morning, 14 February, there was a brief thundershower (0.02" rain) with some lightning.


The sky began clearing mid-morning on Sunday, 14 February.

Open: Sunday, 14 February 2021, 1800 MST
Temperature: 62°F
Session: 1596
Conditions: Mostly clear, breezy

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
2" UHC, OIII, HA filters
Filter Slider System

iPhone 11 Pro Max

1805 MST: LX600 ON, StarLock OFF, High Precision OFF.

1808 MST: sunset (time approximate due to clouds).

Shortly after sunset the western sky looked like this iPhone 11 Pro Max photo.


Viewed the crescent Moon, 102X.

Mounted the D850 DSLR at prime focus using the Starizona Filter Slider System. Took these photos (1/320sec and 1/2sec, ISO 640) of the Moon.

photo photo

1828 MST: the breezes had calmed down.

1910 MST: dome OFF (onto PZT).

Focused on the star Aldebaran with the UHC filter, locked the 12" primary mirror, and SYNCed on the star.

1925 MST: StarLock ON.

Took the following StarLock autoguided exposures (5 minutes, ISO 12800, White Balance 4550K, unedited) of M1 (Crab Nebula).

photo photo photo

Using Adobe Photoshop, the photos were merged, edited, and cropped with this result.


1951 MST: StarLock OFF.

2001 MST: viewed M1, 102X. Added the UHC filter, which darkened the moonlit sky background. Then viewed M42 (Orion Nebula), 102X + UHC filter. Nice view with lots of detail visible.

2007 MST: LX600 OFF.

2015 MST: dome ON.

Close: Sunday, 14 February 2021, 2021 MST
Temperature: 41°F
Session Length: 2h 21m
Conditions: Clear

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 ©2021 Michael L. Weasner /