A few nights ago I grabbed some frames of Alnitak, Zeta Orionis. This is one of the stars in Orion’s belt, and is close to the Flame Nebula and the Horsehead. Neither nebula was visible in the RAW images, though a hint of the Flame could be distinguished with a little charity for the image. Combining 10 30-second images wasn’t really all that helpful – the Horsehead in particular needs more time. However, with a lot of pushing of the envelope, here’s what I was able to pull out of the noise (and it is noisy!):
Roll your cursor over the image to identify details
Both the Flame and the Horsehead are visible, but the granularity of the image is such that the Horsehead is only a feature if you know it is supposed to be there. Meanwhile, the yellow area above and to the left of Alnitak is quite spurious, and is most probably a remnant of the extensive sky fog which is imperfectly edited out of the image.
The moon was a killer last night (November 17). With temperatures around – 6 C it was difficult setting up around 11.30 pm. The SkyShed is still sticking — haven’t gotten around to fixing it yet — but opened with only a little difficulty. I don’t usually observe during the week as I don’t generally deal well with lack of sleep these days (thirst and sleepiness being the more obvious signs of my diabetes when it’s out of control), but tonight I made an exception as I really wanted to get an in-focus image of the Great Nebula in Orion, as well as try to capture the Running Man Nebula. I found that 30 seconds at ISO 800 was about the best I could hope for, so I set the camera to catch a burst of 40 images, and then repeated the burst after changing the CF card. I grabbed 5 flats and 5 darks at the end of the session since conditions were about the same over the session’s duration. I packed up around 12.30 am as clouds rolled in, though by the time I finished packing up, the clouds were gone — I probably could have imaged another hour or so based on the Sky Clock predictions.
So what did I get? The images are in focus. However, there are many frames where the image is spoiled by seeing, possible PE, and so on. I have good, clear images of the inner nebular features, but pulling out images of the outer nebula is virtually impossible due to the overriding and irregular light wash from the Moon. By the time I pull features from the eastern side of the nebula, the western side is a waste, and if I manage to extract the Running Man, the Great Nebula is blown away. It’s very frustrating.
I believe I can create a useful final image but not in Photoshop alone. It may be time to go looking for a dedicated astro-imaging package such as Images Plus or Maxim DL (actually, I’d probably go for Images Plus over either Maxim DL or its little brother Maxim DSLR, purely on feature/price ratios). That may have to wait a while though — one of the other things I found last night was that the memory I added to my laptop is flawed and will have to be replaced. It should be under warranty – except that I can’t find the invoice. AAAAAARGH!
I still have problems adjusting dust mote shadows out of my astro images. This
was from my session of November 12/13, and has been adjusted for darks and flats, but still displays lingering traces of dust shadows in at least three locations. There were 11 images, each at 30 seconds, and I used all of them, despite the fact that the image focus slipped during the course of the evening. I wasn’t using the computer to preview the original images, and the focus shift was not caught until quite late in the session.
This image was the result of several tweaks in Photoshop to adjust levels and curves and bring out the fainter parts of the nebula. I zigged when I should have zagged, though, and overwrote the working document with all its layers and replaced it with a smaller image copy. I’ll have to start from scratch, dammit!
And this is what I got, the second time around:
The detail around the Trapezium is clearer, and the dust bunnies are a little less pronounced.
Incidentally in most browsers you can right-click (option-click for Mac users) on an image to view it in a separate window at a larger size.
It’s been pretty wet the last few days, not to mention cold, so I was happy when the Clear Sky clock started showing a little blue for a change. I held off going out until about 3 am and ran into the same problem as in September – the roof was stuck. I could probably have opened it, but the noise would have woken up all the dogs in the neighborhood and I don’t need the kind of neighbourly rancour that could trigger, so I let it be after a quick check to see if I could see anything easily fixable. I couldn’t, so I posted a message off to the SkyShed user group to see if they had any suggestions. This is a great group for advice on building and maintaining the SkyShed from Wayne Parker’s CD, but I was surprised the following morning when Wayne gave me a call to ask for more details. It seems to me that the wood on one side of the roof is warping – remember, it’s been raining for a while – but Wayne suggested it might simply be the tolerances were a little tight when the shed was put together. I’m going to send him pictures as necessary to figure out what’s happening, and then he’s going to have his installer, Jay, come by and fix things. This goes beyond regular service, and I’m impressed. After all, it’s over a year since the SkyShed was put up, and I’ve been using it a good deal over the summer (not to say I wouldn’t have preferred more use, but any clear weekend and a few clear weeknights would see me out in the SkyShed peering through the scope [and messing up the alignment]). Wayne’s attitude is great stuff.
(Hey, folks – Wayne’s also part of a band you may have heard of – Glass Tiger – so go buy an album)
Despite a touch of something fluish, I forced myself out to the observatory on Friday night. I could see Mars pretty easily, but I wanted to catch a deep space object. The weather started off clear, but there was a definite haze as sunset approached, and by the time I did a cold start and built a new model it was pretty clear that the weather was not going to be cooperative. I did an exposure of the Pleiades at 30 seconds with ISO 1600 and blew the sensor out – white from one side to the other. I pulled the sensitivity back to ISO 400 and started capturing at 30 seconds through the FLT-110 at prime focus. The images were badly fogged, and ultimately I had to re-balance them for Tungsten before I could see colours which were even close to correct. The clouds were in and out for much of the time, and I closed up for a while thinking I was done for the night. About twenty minutes later I opened up again as the band of clouds seemed to have moved on, but less then half an hour after that I had shut done for good. Here’s what I captured:
This is the result of prodding and poking at a mere eight of the 30-second images for a couple of hours working — fighting! — to bring out the colours. I strongly suspect at least some of the nebulosity around the stars is not real — sometimes you can push a little too hard. Meanwhile there is some residual sky fog and a couple of dust rings which are largely removed using flat and dark frames, but I didn’t use them in generating this version. Maybe next weekend….