Cassiopeia Observatory logo

Horsehead Nebula HA, iPhone M81 & M82

Posted: 20 February 2020

Open: Wednesday, 19 February 2020, 1815 MST
Temperature: 75°F
Session: 1442
Conditions: Mostly clear

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
2" 30mm eyepiece
2" 50mm eyepiece
SHO filters

iPhone 11 Pro Max

1820 MST: LX600 ON, StarLock OFF, High Precision OFF.

1829 MST: after several minutes of searching I finally located faint Mercury against the bright twilight sky in the 7x50 finderscope. Viewed the thin crescent Mercury, 102X. Then viewed the near half-phase Venus, 102X.

Slewed to the star Rigel and SYNCed the AutoStar in preparation for imaging IC434 (Horsehead Nebula). Prepared the D850 DSLR for imaging using the Optolong SHO filters and Starizona Filter Slider.

1900 MST: dome OFF.

I noticed that Betelgeuse appeared to be a little brighter than it has been for awhile.

1910 MST: mounted the D850 DSLR at prime focus of the 12" telescope.

1929 MST: the Zodiacal Light was nicely visible in the western sky 6 minutes before the end of Astronomical Twilight (1935 MST).

Focused on Rigel using a Bahtinov Mask with the HA filter inplace, locked the primary mirror.

1935 MST: High Precision ON.

Slewed to IC434 (Horsehead Nebula).

1938 MST: StarLock ON.

After doing some framing test exposures I took StarLock autoguided, White Balance 5560K, images through the HA (5 minutes, ISO 6400), OIII (10 minutes, ISO 12800), and SII (10 minutes, ISO 12800) filters. I then did a StarLock autoguided, White Balance 5560K, 5 minutes, ISO 6400, without any filters to use as a "luminance" image. The OIII and SII images essentially had no images of the Horsehead Nebula in the light frequencies they passed, which was not surprising for this object. I merged the HA and luminance images with this result.


Unfortunately, light streaks from a bright star outside of the camera field-of-view (FOV) marred the image.

2057 MST: dome ON.

Slewed to M81 (Bode's Galaxy), SYNCed on it, viewed it at 102X. Began preparing for iPhone Messier Catalog imaging. Switched to the 30mm eyepiece and mounted the iPhone using the Levenhuk adapter. I imaged M81 and M82 (Cigar Galaxy), StarLock autoguided, afocal 81X, using the iOS app NightCap Camera (Long Exposure, Light Boost, ISO 12500, 1 second, 1 minute exposure).

M81 (Bode's Galaxy)

M82 (Cigar Galaxy)

The details in M82 are impressive for a smartphone image.

I switched to a 50mm eyepiece, which put both galaxies nicely in the same FOV. Took this StarLock autoguided, afocal 49X, NightCap Camera (Long Exposure, Light Boost, ISO 12500, 1 second, 1 minute exposure).


2131 MST: StarLock OFF, High Precision OFF.

Viewed M81 and M82 galaxies, 49X.

Viewed M42 (Orion Nebula), 49X and 102X.

2136 MST: LX600 OFF.

2146 MST: took a Sky Quality Reading and reported the result to Globe at Night.

Close: Wednesday, 19 February 2020, 2153 MST
Temperature: 53°F
Session Length: 3h 38m
Conditions: Clear, breezy, SQM 21.09

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 ©2020 Michael L. Weasner /