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Horsehead Nebula

Posted: 7 February 2021

Open: Saturday, 6 February 2021, 1754 MST
Temperature: 75°F
Session: 1592
Conditions: Clear

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
2" 5.5mm 100° eyepiece
1.25" 26mm eyepiece
1.25" 40mm eyepiece
Filter Slider System
2" UHC and HA filters
1.25" HB filter

iPhone 11 Pro Max

1801 MST: sunset (time approximate).

1802 MST: LX600 ON, StarLock OFF, High Precision OFF.

Viewed the double star Rigel, 102X and 443X.

Relaxed on the observatory patio bench while waiting for the sky to get darker.


1834 MST: viewed Rigel, 443X. Used its companion star for scaling in my attempt to observer Sirius B (the "Pup Star").

1845 MST: viewed Sirius A, low in the southeastern sky, 443X. No Pup Star seen. Returned to the bench.

1853 MST: handheld iPhone 11 Pro Max photo (Night Mode, 3 seconds, 1X lens) taken from the bench showing Gemini (left), Orion (right), and the star Sirius (lower right).


1857 MST: back inside the observatory. Made several attempts at observing the Pup Star, but no success.

1919 MST: viewed Mars, 443X. Some surface details visible. Gibbous phase obvious. Mars, 102X, no details visible.

1931 MST: High Precision ON.

Slewed to IC434 (Horsehead Nebula). Some nebulosity was visible, 102X, but no Horsehead was seen. I attached the Starizona Filter Slider System with the eyepiece holder. Used UHC, Hydrogen Alpha, and Hydrogen Beta filters at 94X and 61X to try to observe the Horsehead. Nothing at all was seen with the HA filter. Nebulosity was seen with the UHC and HB filters, but no Horsehead shape detected.

1954 MST: dome OFF.

Mounted the D850 DSLR at prime focus using the Filter Slider, focused on the star Rigel using the UHC filter, and locked the 12" primary mirror. Slewed to the Horsehead Nebula.

2013 MST: StarLock ON.

Did some framing test images. It was a challenge to eliminate an optical flare from a bright star just outside of the camera field-of-view. Once I did I took StarLock autoguided, 5 minutes, ISO 12800, White Balance 5000K, exposures through the UHC, HA, and HB filters (seen below, left to right, cropped). A satellite crossed through the UHC image. The full-frame HB image had vignetting from the 1.25" filter.

photo photo photo

I merged the three images in Photoshop with this result.


2100 MST: StarLock OFF, High Precision OFF.

Viewed M42 (Orion Nebula), 102X.

2111 MST: LX600 OFF.

2126 MST: dome ON.

2132 MST: did a Sky Quality reading and reported the result to Globe at Night.

Close: Saturday, 6 February 2021, 2137 MST
Temperature: 47°F
Session Length: 3h 43m
Conditions: Clear, breezy, SQM 21.06

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