IC 405 – Emission/Reflection Nebula in Auriga

Telescope: Meade N6 at f/5, Orion Atlas EQ-G
Camera: Full-spectrum Modified Canon 600D, Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro III, PHD
Exposure: (37+29)x120sec ISO 800 saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flat: 32x1/250sec, ISO 800, tee shirt flats taken during twilight
Average Light Pollution: Red zone, fair transparency (both nights)
Lensed Sky Quality Meter: 18.5-18.7 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard EOS, Nebulosity, Deep Sky Stacker, Photoshop

This image came as a complete surprise. I had no idea such a beautiful nebula lay among the open clusters in Auriga. I was also surprised how it appeared from my skyglow as the image processing proceeded. The nebula was absolutely invisible in the subs and barely showed anything in the calibrated stack. I was delighted that I was able to separate it from the skyglow and preserve at least some of the beautiful contrast between the blue reflection nebula and the red emission nebula.

The nebula that comprises IC 405 is illuminated by the variable star (Mv 5.8-6.1) AE Auriga. However, this star is not associated with nebula and only happens to be passing through this region as it streaks northward. AE Auriga also has an unusual companion; Mu Columbia a star streaking southwards halfway across the sky. Tracing the flights of these stars backyards suggest that they intersect where is now the quadruple star Iota Orionis on the southern fringe of M42. These three systems, AE Auriga, Mu Columbia, and Iota Orionis, may have originally been part of the Trapezium cluster, but a complex close encounter ejected AE Auriga and Mu Columbia, leaving the Iota Orionis system behind.

The source images for this field were collected over 2 evenings; 37 on 11/23 and 29 on 11/25. The sky conditions were okay, but a bit a bit variable. If we get an evening of perfect transparency I’d like to try this again.


IC405 (11-23&25-2017)-2j.jpg