California Dreaming

I've wanted to image the California Nebula for some time, but always assumed it was out of my reach because it is too large for my optics and its surface brightness is too low (I thought). My wife and daughter are both native California girls so California has a special place in my heart. Realizing this nebula is a hydrogen-α emission region, I decided to give it a try with the Hα filter. Since the Moon is bright again, it was time to make the attempt. To maximize my field of view, I decided to go with my ST80 telescope with a focal reducer.

I've been using my AT8IN Newtonian reflector recently, so I needed to switch telescopes. In the past this has been a pain because I'd have to move my finder/guider and my Telrad sight from one scope to the other, then realign all the optics. This time I decided to try the switch to the ST80 scope "cold turkey": I just mounted the finder/guider on the ST80 without changing any alignment and didn't even bother to take the Telrad sight off my AT8IN reflector, so I'm not using anything to aim the ST80 scope other than bare eyeballs along the optical tube. I did look at the Moon first to make sure the ST80 was focused. Anyway, the plan was to rely on Astrotortilla to find the target. It didn't work at first, until I realized I was setting Astrotortilla to the field of view of the AT8IN, not the wider field of the ST80. It's a little challenging to do Astrotortilla plate solves with the Hα filter in place (because the filter drastically cuts down the number of stars visible in the image), and to top it off, my Peltier cooler failed big time while I was doing this and just got hot instead of cooling. The CCD temperature got up into the 40's (Centigrade) before I realized something was wrong and numerous hot pixels masqueraded as stars, competing for Astrotortilla's attention. Fortunately the weather has turned cold, so the CCD was down below 5 °C once I really got the session rolling. Eventually, I did get plate solving to work after setting the field of view correctly and taking longer exposures. The California Nebula was quite easy to find once I got the scope aimed at the star ε Per; the thing is HUGE! I shot 2 sections of a mosaic, but *!#*! Windows decided to shut itself down for updating in the middle of the second session. I need to figure out how to shut off that autoupdate "feature." So much for staying up half the night to perform a meridian flip; my California Dream was a bit interrupted!

I've mentioned before that I'm a bit undecided about whether to present these Hα images in grayscale or in false color. I think maybe you can see more contrast in grayscale, but I like false color and the algorithm I'm using to do it (from Noel Carboni's Astronomy Tools suite in Photoshop) does a nice job. So this time I decided to have the best of both worlds and make an animated GIF that fades between the two views. I was a bit surprised at how many "likes" this got on Astrobin; it's an OK image, but I think it could be better.

One last aside: while I can see a resemblance to the state of California, I think this nebula looks more like a squid. The head is to the left, a dark eye is in the middle, and the tentacles trail to the right.

Date: 3-4 Nov, 2014

Subject: NGC 1499, California Nebula

Scope: Orion ST80 + Antares 0.5x telereducer

Filter: Baader Hα

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

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

Camera: DSI IIc no cooling

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 22+9x600 s (2 panels)

Stacking: Neb 3, bad pixel map, bias included, flats, OSC extract R, normalize, square, trans+rot align, 1.5 SD stack resize 2x.

Processing: StarTools 1.3.5.289 Crop; Develop 50%; HDR:Optimize; Life:Less=More; Deconvolute: 3.0 pix; Track 5.0 pix; Magic 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Layer mask align & combine; Levels to match backgrounds; Hα false color black background in one panel; Astroframe.