A reprocess of some old Sky90 data.
As there’s not been much imaging going on lately (weather), I’ve been browsing through old data. Just came across another 20 x 15-minute subs taken with the 200mm lenses which I’ve put together with 20 x 15-minute subs of the same region taken a few years earlier. I’m going to have to take a deeper look at what I’ve got stored in various HDD drives as I’ve completely lost track of what I’ve done.
Only managed to get 8 x 5-minute subs of M78 with the Hyperstar 4 through thin high cloud before the heavy cloud rolled in. Noel Carboni was still able to pull out some nice detail even though there is only 40-minutes of data.
I had absolutely no idea it was an ISS lunar transit last night, which is why the picture is so badly framed. But at least I captured it.
And here is the single frame of the transit.
Managed to get today’s EPOD with that mass of Milky Way stars taken with the 200mm lenses that looks like magnified grains of sand on the beach. Thank you Jim for continuing to publish my work.
And here is a professional process of the Rosette data by my friend and astro-colleague, Noel Carboni.
I managed to get 10 x 4-minute subs on the Rosette nebula last night before the cloud rolled in (I think it all cleared again a couple of hours later). But I really can’t complain about this image when you consider there’s only 40-minutes worth of data there. Such is the power of the Hyperstar 4.
Here’s just the Hyperstar 4 data for the recent M31 image – only 16 subs at 3-minutes per sub. Now if only I can get the skies for 100 x 3-minute subs, this will start to look stonking. This version of M31 was professionally processed by Noel Carboni.
I said I wouldn’t divulge the secret if the result was good. As the result wasn’t particularly good, I’ll tell you how it was done. The ultra-fast Hyperstar 4 at f#2 will blow the core of M42 (the Trapezium region) with anything over 1-second exposures. I suppose you could use even shorter exposures, but then you would be adding more camera noise to the image as well as having the poor SNR of a short exposure. So my idea was to take longer exposures, to get away from the camera noise, by reducing the luminosity of the core region. But how can you do that? I was given the idea over 17 years ago when I was visually observing the core region with the C11 at its native f#10. I couldn’t see the Trapezium stars of course, as the region was just too bright – but then a cloud drifted across M42, and just for a moment I saw the Trapezium stars, very clearly. So there was the clue. To mimic the cloud I bought a Neutral Density Filter (10 stops) and it certainly did a great job in cutting down the luminosity, but the resulting image at f#2 is a bit disappointing as the region takes up too little space in the whole field of view. So although the idea works, in principle, it’s not the best way to image this one.
Clear Moonless sub-zero night last night so I was expecting some great results from the Hyperstar 4.
Managed to get 25 x 5-minute subs with good collimation, and the above image is the result. It’s terrible. Virtually no dust which came out well using the Sky90 array.
Must admit, the sky did look rather light, and I guess it was full of ice crystals. First time I’ve had that as an issue.
