Catching Tadpoles

When I was little, I used to catch tadpoles from the pond and watch them metamorphose into frogs. So I was intrigued a few years back when I saw images of the Tadpole Nebula in 100 Best Astrophotography Targets. It has two pillar structures that very much resemble the little immature amphibians. I tried several times to image the nebula, but could never really see the tadpoles, and concluded that they were just beyond the ability of my gear. Well, it wasn't my gear. With the Hα filter performing well on emission nebulae like this one I've been anxious to try it on IC 410, the Tadpole Nebula. Sure enough, the tadpoles were easily visible in my subframes. The full moon was quite near during this session, and probably hurt the contrast in the image a bit. I'm only intermittently able to get Astrotorilla plate solves when using the Hα filter, and this session was no exception to that. I initially synched on β Tau, did the goto, and imaged up to the meridian. After doing a meridian flip, I tried to use Astrotortilla to resynch and reacquire, and it just kept driving the scope farther and farther AWAY from the target. I wasted about an hour of sleep time messing with it, then finally went back out and manually aimed at β Tau, synched, and went right to the target. My chiller is still broken, but CCD temperatures started at 10 °C and fell as the night wore on. The tadpoles are easily visible in the stacked Hα image at the upper left, "swimming" toward the core of the nebula. I've been having fun working out how best to present Hα data, and finally settled on what you see here, an animated GIF that alternates between greyscale, which I think shows a bit more detail, and Hα false color, which is close to the true color emitted.

Date: 7 Nov 2014

Subject: IC 410, Tadpole Nebula

Scope: AT8IN + Antares 0.5x Telereducer

Filter: Baader Planetarium 7 nm 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 chiller 5-10 °C

Acquisition: Nebulosity 3.2.1, no dither

Exposure: 41x600 s

Stacking: Neb 3, bad pixel map, bias included, no flats, OSC extract R, normalize, trans+rot align, 1.5 SD stack resize 2x.

Processing: StarTools 1.3.5.289 Crop; Develop 60.00%; HDR:Optimize; Deconvolute: 5.0 pix; Track 5.1 pix; Magic 1 pix. Photoshop CC 2014 + Carboni Astronomy Tools Hα false color dark space; Astroframe; assemble animated GIF by pasting uncolorized layer on top of false colored layer and manually aligning then making frame animation.

Encouraged by this result, I decided to dig up some older RGB data that were obtained at the same imaging scale and make a composite image. The RGB data are really pretty lousy (the subframes were not exposed long enough, and I probably should have used the UHC-S filter to improve the contrast). I had some trouble aligning the layers even though I pre-aligned them using Nebulosity. The red channel is 25% from the RGB and 75% from the Hα, and the Luminance came from Hα with 80% opacity. I was quite pleased with how the composite turned out, especially given how bad the RGB looked.