NGC1909 Witch Head Nebula

NGC1909 Witch Head Nebula; multi-session image with data captured from Los Alamos, NM on 14 October 2023 and from CSASTRO’s Starry Meadows on 4 November 2023; both with the Southern Cross

Fun facts

NGC1909 (also known as IC2118 and named the Witch Head Nebula due to its shape) is an extremely faint reflection nebula believed to be an ancient supernova remnant or gas cloud illuminated by nearby supergiant star Rigel in the constellation of Orion. The nebula lies in the Eridanus Constellation, about 900 light-years from Earth. The nature of the dust particles, reflecting blue light better than red, is a factor in giving the Witch Head its blue color. Radio observations show substantial carbon monoxide emission throughout parts of IC 2118, an indicator of the presence of molecular clouds and star formation in the nebula.  Candidates for pre-main sequence stars and some classic T-Tauri stars have been found deep within the nebula.

The molecular clouds of IC 2118 are probably juxtaposed to the outer boundaries of the vast Orion-Eridanus bubble, a giant supershell of molecular hydrogen blown by the high mass stars of the Orion OB1 association.  As the supershell expands into the interstellar medium, favorable circumstances for star formation occur.  IC 2118 is located in one such area. The wind blown appearance and cometary shape of the bright reflection nebula is highly suggestive of a strong association with the high mass luminous stars of Orion OB1.

Distance: 1000 light years
Apparent magnitude: 8.0 (Stellarium) 13.0 (Wikipedia)
Apparent dimensions: 3°x1°
Constellation: Eridanus
Designations: NGC1909, IC2118, vdB36, LBN959, Ced41

{ Target information from and Stellarium }

Capture & Processing Notes

This image is comprised of data from two imaging sessions – the night of the annular solar eclipse from Urban Park in Los Alamos, New Mexico; and a night of imaging at CSASTRO’s Starry Meadows property near Gardner, Colorado.  It was the second target on both nights, as it is a “late riser” but definitely one to be captured in dark skies.  (So this may just be the start of data capture on this object for this year’s “nebula season.”)

During the Los Alamos capture (14Oct2023), although there were no clouds, the sequence ran from 0115 – 0305MDT when the autoguider lost its guide star.  Since I had been returning to the North Road Inn to catch some sleep in-between times the equipment needed attention, I didn’t discover that the sequence had terminated until I went out to the park to do the meridian flip at approximately 0500MDT.  I debated about just giving up at that point, but there was still over an hour before nautical twilight, so I got the session started up again.  It ran 0504 – 0622MDT (capturing 15 more subframes). 

During the Starry Meadows capture (4Nov2023), again the Witch Head was the second target of the evening beginning at 2314MDT.  On Sunday morning, 5 Nov2023 we were scheduled to come off Daylight Savings Time.  I guess I’ve never really watched what the clocks do when they “fall back” out of DST.  Maybe it was the cold or the sleep deprivation from trying to sleep in the back of the Expedition – setting my alarm for the meridian flip at 0210MDT threw me for a loop.  I never got to the alarm – I had looked at my watch – it said it was 0144.  I dozed off.  When I woke up again a few minutes later (did I mention I wasn’t sleeping well in the Expedition?), it said it was 0108.  I stared at my watch for several minutes, then checked my phone – hmmm, same time.  I glanced outside and saw the telescope was parked.  Disregarding my time-warp confusion, I got up to get the sequence going again, presuming it was the clouds that were beginning to move in that had confused the autoguider.  In the process, I looked at the last image that had been taken – it was time stamped 0146.  The clock on the computer said 0115.  Apparently, the clue bird had flown south for the winter because it still wasn’t coming to me.  I got the sequence going again (with some issues – because (still unbeknownst to me) I was so close to the meridian).  I finally got the sequence going again at 0117(MST) and tried to go back to sleep.  There wasn’t much sleep going on because by this time of the night, I was thoroughly chilled and shivering.  While I was laying there, not sleeping, I finally figured out the “fall back to 0100MST” algorithm that all my time pieces had executed at 0200MDT!  The clouds were rolling in.  Amazingly enough, there was a small hole (not even completely clear) in the clouds right where the target was, so the telescope (and autoguider!) were still working.  But, at about 0315 I’d had enough, so I ended the sequence, packed up the gear, and headed home. 

Sequence Plan(s): Image is comprised of data collected during two imaging sessions, the first at Urban Park, Los Alamos, New Mexico on 14 October 2023.  The second at CSASTRO’s Starry Meadows, near Gardner, Colorado on 4 November 2023.  Total imaging time in image is: 7:10hrs.

  • Sequence plan (14Oct2023, Los Alamos): Gain: 158, Temp: -0°C, offset=30; 36x5min; Total exposure time: 3:00hrs.
  • Captured: 14 October 2023 (14Oct23, 1944MDT – 15Oct23, 0101MDT);
  • Shooting location: Urban Park, Los Alamos, New Mexico
  • Sequence plan (4Nov2023, Starry Meadows): Gain: 158, Temp: -0°C, offset=30; 50x5min; Total exposure time: 4:10hrs.
  • Captured: 4 November 2023 (4Nov23, 2314MDT – 5Nov23, 0146MDT and 5Nov23, 0117 – 0316MST (gap in imaging from 0146MDT – 0117MST, as DST ended right about the time of the meridian flip)
  • Shooting location: CSASTRO Starry Meadows, Gardner, Colorado

Processing summary: Captured with SGP. Stacked in APP. Star removal with Starnet++. Processed in LR/PS


All equipment controlled by HP Probook (DSO CTRL 1) Windows 10 laptop running Sequence Generator Pro v3.2.0.660.  

  • Polar alignment: QHYCCD camera (controlled by Polemaster for polar alignment)
  • Imaging: (Southern Cross) Askar FRA600 on Rainbow Astro RC-135E, ZWO ASI2400MC#1 camera
  • Mount: Rainbow Astro RC-135E (controlled by iHubo ASCOM driver)
  • Autoguiding:  Orion 60mm Multi-Use Guide Scope with Orion StarShoot AutoGuider Pro Mono Astrophotography Camera (controlled by PHD2)