The "69" nebulae...

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Object: IC 410 and IC 405 (The "Flaming Star" Nebula, Caldwell 31)

Type: Emission Nebulae

Distance: 1,600 light years

Constellation: Auriga

Date: 23 January 2009

Equipment: SXV-H9, Zeiss 135mm telephoto lens @ f3.5 (40 mm aperture), ATIK filter wheel with Ha, G&B filters

Subframes: 40 x 200s 2x2 binned subframes in H alpha, 12 x 200s 2x2 binned in G, 5 in B, 16 darks, 16 flats/flat darks in Ha, calibrated and stacked in AIP4Win. Final processing in AstroArt, Paint Shop Pro7 and NeatImage.

Despite an ever-increasing haze that cut short my imaging session for this one (hence only 5 blue subs in the end), I was reasonably pleased with the end result. I had planned to take loads more subs if the sky held but given recent history, I was glad I had decided to take a few subs through each filter in turn rather than long sessions through each one.

The channels were stacked in AIP4Win and assigned and aligned in PSP7. The final image was a touch noisy because of the small number of subs, but a quick pass with the freebie version of NeatImage did quite a reasonable job in cleaning it up.

As for the name I gave it, I was just surprised at how sharp the "small 6" of IC410 and "big 9" of IC 405 stood out on the H-alpha frame. The effect isn't quite so striking on the final colour version.

Maybe the final result maybe isn't as good as this one from Greg Parker's New Forest Observatory, but given my somewhat "lower budget" set-up (below), I think I've got value for money on this occasion - especially given the weather...

The shot above (click on the image for a clearer view) shows my current system for wide-field imaging. The equipment is all mounted on a Vixen plate, with the SXV-H9 clamped in a simple bracket made out of a bit of copper tube that I flattened down and drilled. This allows me to rotate the camera for image framing. The filter wheel and lens (with mandatory dew heater) sit on the camera: I've found the filter wheel leaks a bit of light so that's what the silver foil is for. An old Celestron 7 x30 finder is used for rough alignment, with the Vixen guidescope and reticule eyepiece that's above it being used for precise alignments.

It's a simple and robust set-up that stands up quite well to being bounced around on my gadget box when I roll it out of the garage.

Messier 45 - The Pleiades...

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Object: Messier 45
Type: Open Cluster
Distance: 407 light years
Constellation: Taurus
Date: 18 January 2009
Equipment: SXV-H9, Zeiss 135mm lens, ATIK filter wheel, Astronomix LRGB filters
Subframes: 30 x 300s full resolution subframes (luminance), 20 x 200s RGB 2x2 binned, 16 flats/flat darks (no darks) in luminance, channels calibrated and stacked in AIP4Win. Final processing in AstroArt and PSP7.

It really has been an exceptionally poor winter for imaging so far, has it not? On the few nights that stars are actually visible, there has been a mist lurking around, robbing the sky of any sort of clarity needed for deep-sky work. This particular evening was not really much better but it had been so long that I’d thought I’d give it a go on something bright, like M45, an object I’d never really had much luck in imaging in terms of capturing the delicate nebulosity that suffuses its stars.

Seeing started poor and a high haze became increasingly heavy during this imaging session. I shot what were going to be the luminance frames for the image (200s at full resolution through a UV/IR blocker) first, followed by the red and green frames at 2x2 resolution, and all the while the sky background on the images was getting brighter and brighter. When I finally shot the series of 200s blue frames, I was amazed at how burnt out the stars looked compared to the red and green channels – perhaps an indication of just how “blue” the Pleiades are (or perhaps the lens has a touch of chromatic aberration). I was going to shoot a series of frames at shorter exposures, but by then the stars were virtually hazed out, so I gave up.

The blue frames were a write-off, so I used the luminance channel as the blue one, and pieced together an RGB composite in Paint Shop Pro. This was a bit fiddley as I’d resized the 2x2 binned red and green channels in AIP4Win to match the full resolution luminance channels. In PSP, not only were those images very slightly smaller than the “unresized” ones, there was a bit of rotation as well, probably because I’d had to reverse the equatorial mount between the red and green frames.

The high haze had also caused some horrible gradients across the raw images, and the stacked ones took quite a bit of processing to flatten them out.

It was all a bit much for the AstroArt RGB processing package, which couldn’t stack the colour frames and introduced a load of new coloured gradients anyway, hence a bit of laborious trial and error work to rotate and resize the composites in PSP7 to get something that could be aligned accurately enough to avoid odd and unequal flaring effects on the stars.

With all of this heavy processing, the final image isn’t too brilliant. The brighter stars are still a bit burnt out – you can’t pick out the three small stars just west of Alcyone, for example, which the best shots can clearly resolve. The nebulosity around Merope and is also rather restricted and doesn’t show the “brush-strokes” you see in really good images of this area of the sky.

Whether that’s down to the poor conditions at the time, a poor processing technique and/or insufficient resolution from the 135mm telephoto lens, I’m not sure.

There are certainly better shots of M45 out there than this one. I think I’ll give up on it for now…