Thor’s Helmet in Canis Major

NGC 2359 is a Wolf Rayet bubble, similar to the Bubble Nebula and the Crescent Nebula. This data was captured in late 2014 and late 2015. By 2015, trees along the southern horizon from my observatory had grown to the point that I had to shoot frames in between the treetops, and a I had to toss many frames. By 2016 it was no longer possible to capture this target, so I processed the data. This is a bicolor, with Ha mapped to red and 20% of blue, and OIII mapped to green and 80% of blue.



Optics/Mount: CPC1100 with f6.3 Celestron reducer on a Milburn wedge. Dec antibacklash set to 27/27. PEC on.
Camera: SXVR-H694
Exposure: Total exposure time about 13 hours; 18 x 20 mins Ha, 19 x 20 mins OIII and 12:15:18 x 60 seconds RGB for star colors. All bin 1x1.
Filters: Astrodon 5nm Ha and 3nm OIII and Astrodon Type IIi RGB
Date: Data was collected over 17 nights between December 2014 and April 2015 and between November 2015 and March 2016.
Imaging automation and capture: Sequence Generator Pro

Guiding Hardware: ASI120MM, Celestron off axis guider. Guiding scale 0.46 arcsec/pixel. 1 second guide exposures.
Focusing: Rigel Systems GCUSB/nStep on stock C11 focuser
Guiding Software: PHD2. RA aggressiveness 55, hysteresis 0, Minimum Move 1.4 arcsecs, Max RA 200, Max Dec 600. Guiding unbinned with ZWO connection. Dec set to hysteresis. Dithering set to Extreme with Settle < 1.2.
Guiding performance: Fair to poor, with FWHM of around 2.8 arcsecs.
Light pollution: Bortle 8 (white zone, NELM about mag 4.5)
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 1.2 arcsecs/pixel (50% reduction)
Processing: Bias, darks, and flats. Stacked and processed with PixInsight, with a few minor modifications in Photoshop.