A Heart and a Rose in Hydrogen Alpha

The sky has been mostly clear for the last few days, but in the past I would not have been able to take advantage of it because we are in the time of the full Moon. (One night that was not clear was the night of the full Moon and lunar eclipse, so I missed that.) Now, as I've noted previously, full Moons don't matter as long as I have an emission nebula I want to image, because my Hα filter rejects all that bright moonlight.

I've never tried the Heart Nebula before because it is much larger than the field of view I can get with any of my scopes (other than using a focal reducer on my finder scope, which produces horrible optical aberrations). But the Heart is a nice H-emission object, so I decided to give it a try and do a mosaic after seeing a nice mosaic by Jammie Thouin on Astrobin (http://astrob.in/126100/0/). My strategy was to use my ST-80 refractor with a focal reducer to maximize the field of view and the optical speed, and line things up to do a 4-panel mosaic. The Thouin image helped a lot in deciding how to frame the pictures. I got two parts of the mosaic each night, so it took two nights to do this. Even though I've seen plenty of pictures of it before, I had no idea how beautiful the Heart Nebula is. And it does look like a heart, though I guess it's one that has some disease because one chamber is bigger than the other. Combining the frames was challenging. I did most of it with Photoshop Photomerge, but a little layer masking also helped to make things blend smoothly.

My first attempt at the Heart Nebula. Synched from ε Cas; the PicGoto centered IC 1805 (the central cluster), which is visible even through the filter with 2 s exposures. Chiller at 2.5 A, T = 9-4 °C. Imaged the left bottom portion 1st, 13 600-s subframes, then moved to the left top portion and ran until the mount bumped, 23 600-s subframes. Perfect conditions on 9 Oct and the result was the best guiding performance I have ever had (so far); RMS < 1". Chiller at 2.5 A, 10.5 °C. Synched from ε Cas on the second night and was dead center. Realigned using a frame from 6 Oct, then moved over to get the next panel of the mosaic. Partway through the run I lost USB connection to my cameras and had to recalibrate; guiding was still very good afterward, but not as good as before, which leads me to believe that guiding performance is more strongly dependent on calibration than I had thought. Combined all but the upper left panel with Photoshop Photomerge; the stubborn upper left panel had to be put in by hand. 

Date: 6, 9 Oct 2014

Subject: IC 1805 / NGC 896 / Sh2-190, Heart Nebula

Scope: Orion ST-80 + Antares 0.5x telereducer

Filter: Baader Hα

Mount: CG-5 (Synta motors, PicGoto Simplificado)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.1 (Win 7 ASCOM)

Camera: DSI IIc chiller at 2.50 A, 3.5 to -1 °C (Oct 6); 10.5 to 9.0 °C (Oct 9)

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 13x600 s (bottom left), 23x600 s (top left), 23x600 (bottom right), 34x600 (top right)

Stacking: Neb 3, bad pixel map, bias included, no flats, OSC red channel extract, normalize, square, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.289 Crop; Develop 65%; HDR:Optimize; Contrast; HDR: Optimize; Life:Moderate; Track Grain size 5.0 pix; Magic:Shrink 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Photomerge, Gaussian blurred layer combine (top left), Hα false color; Astro Frame.

Sh2-206 (which doesn't have a common name as far as I know) reminds me of the Iris Nebula, but it's the wrong color as it shines mostly in Hα rather than by reflection like the Iris. So this nebula looks more like a rose. I’m starting to stray a lot from the "Top 100" list, and this is a foray away from it. 

Synched from α Per and found on the first try with the PicGoto. The core of the nebula is visible even at 2 s in the imager, but the fringes are much fainter. Not many bright stars in my field of view either, but without trouble I did find a guide star bright enough for my usual 1 s guide exposures. Chiller at 2.5 A, 11 °C. Before I went to bed I noticed the guider was having some trouble keeping the guide star aligned in Dec, and I should have paid attention because shortly thereafter the problem became severe. I think the Dec clutch was probably slipping, but in any event I got a lot less data than I had planned to get. Eventually, the whole session hung because the USB connection dropped. I need to solve that problem!

Date: 10 Oct 2014

Subject: Sh2-206 / NGC 1491

Scope: Astrotech AT8IN + Antares 0.5x telereducer

Filter: Baader Hα

Mount: CG-5 (Synta motors, PicGoto Simplificado)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.1 (Win 7 ASCOM)

Camera: DSI IIc chiller at 2.50 A, 11.5-9.0 °C

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 20x600 s

Stacking: Neb 3, bad pixel map, bias included, no flats, OSC red channel extract, normalize, square, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.289 Crop; Develop 50%; HDR:Optimize; Life:Moderate; Track Grain size 5.0 pix; Magic:Shrink 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools deep space noise reduction, Hα false color; Astro Frame.

I'm planning to try the γ-Cassiopeia "Ghost of Cassiopeia" Nebula next, another Hα emitter.