12/27/2013. I started collecting narrowband data for a photo of IC 405 (the "Flaming Star Nebula") around AE Aurigae night before last as an afterthought to an image of IC 63. The sky was clear; the 'scope was tracking well and holdng focus; I thought I might as well ask it to do something. That first night's take (two hours in hydrogen alpha) is shown on the previous page. I followed up last night by taking an hour of color data and then added four more hours of hydrogen-alpha.

AE Aurigae is a variable star about 30,000x brighter than the Sun. It was ejected from the sword of Orion about 2,000,000 years ago and now races through a cloud of hydrogen north of its origins at about 120 km/sec. Its brilliant blue-white light is both illuminating and exciting the gas with which it finds itself surrounded. The interstellar gas shines by both reflected and emitted light. Ultraviolet light from the star not only causes the gas to glow with a blood-red light, it also erodes the cloud. Look especially in the lower third of the image where knots of dense gas shade the gas "below," creating towers of glowing hydrogen the way capstones create red rock mesas Out West. There are also some intriguing, very thin dark threads beginning to become visible with the shutter open for six hours. Maybe more exposure is called for. (It usually is.) Here's the complex field in the light of hydrogen-alpha:

 

AE Aurigae with IC 405
12x1800s (6 hours) with 7nm Baader H-a filter
AT10RC @ F4.8, ST2000XM @ -20°C

 

Add an hour of red, green, and blue data (20 minutes in eight 150 second gulps in each channel) and some aspects of what's going on become more apparent. The distinction between emitted and reflected light is clear. The deep red is hydrogen emission, and where the nebula is tinged with blue, it shines also by reflected starlight. Look:

 

AE Aurigae with IC 405
12x1800s (6 hours) with 7nm Baader H-a filter
8x150s RGB (1 hour total)
AT10RC @ F4.8, ST2000XM @ -20°C

 

 

 

 

Except where noted, deep-sky photos are made with an SBIG ST2000XM CCD behind a 10-inch Astro-Tech Ritchey-Chretien carried on an Astro-Physics Mach1GTO. The CCD is equipped with Baader LRGB and 7nm H-a filters. The internal guide chip of the CCD most often keeps the OTA pointed in the right direction (I'll let you know when a Meade DSI and a separate OAG or guidescope takes its place). Camera control and guiding are handled by Maxim DL 5.12. The stock focuser on the AT10RC has been augmented with Robofocus 3.0.9 using adapters turned on the lathe downstairs. Maxim performs image calibration, alignment, and stacking; Photoshop CS4 and FocusMagic 3.0.2 take it from there. Gradient Xterminator by Russell Croman and Astronomy Tools by Noel Carboni see their share of work, too. Beginning in May 2013, PixInsight has taken over some of the heavy lifting for transfer function modification and deconvolution.

 

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