SH2-119 Clamshell Nebula

SH2-119 Clamshell Nebula; captured from Urban Park, Los Alamos, New Mexico with the Southern Cross on 14 October 2023

Fun facts

Sh2 -119 is a diffuse nebula in the constellation Cygnus.  It is located about 2 degrees west of the North America Nebula and 9 degrees west of the bright star Deneb; it appears to envelope the star 68 Cygni.  Its shape appears similar to two shells that are arranged to the east and west of 68 Cygni; the eastern part is the largest. In the southern part, thin filaments and cocoons of dark nebulae are visible, which contrast strongly both with the light of the nebula and with the rich background star field. The distance of Sh2-119 is estimated at 2200 light years from us.

Distance: 2200 light years
Apparent magnitude: 4.2
Apparent dimensions: 2°30’ x 1°
Constellation: Cygnus
Designations: SH2-119, LBN391

{Target information from and Stellarium}

Capture & Processing Notes

Capture Notes: Our “dark skies” trip for October was in conjunction with the trip for the annular solar eclipse.  We originally planned to get a campsite at Chaco Canyon to watch the eclipse from there, but were defeated by the NPS campsite reservation system.  So, settled on Los Alamos as a spot within the path of maximum eclipse (knowing that trying to get a hotel room in Albuquerque during the second weekend of Balloon Fiesta would be as fruitless as our attempts at a Chaco Canyon campsite).  Paul found the North Road Inn for our accommodations, which turned out to be perfect! It was caddy corner across the street from Urban Park where we set up for the eclipse and for DSO imaging (after confirming with a local that we met during the eclipse, that my equipment would be safe on its own while I went back to the room. He said, “This is Los Alamos, other than the bears, no one will bother it”).  We arrived in Los Alamos on Thursday, 12 October.  The night was clear, but I was too tired from the travel, it was dark after we finished a birthday celebration without any setup accomplished, and when Jan and I walked down to the park to check it out we found it to be eye-wateringly windy and cold.  So, I decided not to image.  Friday night was forecast to be cloudy.  Although Dave reminded me of my Milky Way imaging advice to him when they were in Sooke, BC, saying “Don’t believe the forecast, set up so you’re ready for when it’s wrong.”  I failed to heed that sage advice – going to bed with and waking up to clear skies – ARGH!  So, on Saturday, come hell or high water, I was going to image! Before it got dark, Dave helped me set up in Urban Park.  We got the sequence for this image started and went back into the Inn for pizza.   I planned to (and did) split the night between the Clamshell Nebula and capturing some data on the Witch Head when it rose after midnight.  In hindsight, I should have spent more time on Clamshell, as the capture of Witch Head was aborted at about 0300 (that I didn’t discover until I came out at about 0430 for the meridian flip) losing over 90 minutes of imaging time.  There were no clouds, so I’m suspecting an east-of-the meridian issue that wouldn’t have happened with Clamshell. Ah well, image and learn…and the data collected on Witch Head will not go to waste.

Capture details:

Sequence plan: Gain: 158, Temp: -0°C, offset=30; 56x5min; Total exposure time: 5:30hrs.
Captured: 14 October 2023 (14Oct23, 1944MDT – 15Oct23, 0101MDT);
Shooting location: Urban Park, Los Alamos, New Mexico

Processing:  Captured in SGP, stacked in APP, star removal with Starnet++, processing with LR/PS (including star reduction of the overwhelmingly “rich star field”)


Polar alignment: QHYCCD camera (controlled by Polemaster)
Imaging stream: (Southern Cross) Askar FRA600 on Rainbow Astro RC-135E, ZWO ASI2400MC#1 camera
Mount: Rainbow Astro RC-135E (controlled by iHubo ASCOM driver)
Autoguider: Orion 60mm Multi-Use Guide Scope, Orion StarShoot AutoGuider Pro Mono Astrophotography Camera (controlled by PHD2)
Equipment controlled by HP Probook (DSO CTRL 1) running Sequence Generator Pro v3.2.0.660.