ollypenrice

Starizona say it is easy. They lie. Olly

It would certainly be best to post a stretched JPEG plus a link to to an unprocessed sub for those who can download it in a reasonable time. What you've posted contains nothing of diagnostic value. Olly

And this is wrong on so many levels... Olly

At 1000mm I used an Atik 460 CCD. Leo Triplet reprocessed. ( Olly Penrice ) - AstroBin M51 TEC140 data only (ollypenrice) - Full resolution | AstroBin IC342, a new approach (ollypenrice) - Full resolution | AstroBin These cameras are no longer fashionable and, therefore, command low prices on the used market. Indeed mine's for sale complete with filterwheel and 6 filters within your budget. Olly

That must be pretty low from Denmark, I guess. Great start to astrophotography. Olly

Is there just one SNR ratio? Or two? Luminance noise and chrominance noise? And what is the consequence of shooting more luminance than colour, as many do? The luminance, of course, captures more photons. Do you make a synthetic luminance from your RGB and add it to the L filter luminance? Olly

I would call that 12 hours of exposure. I'm sure that's pretty much a universal convention. Olly

It might be ERE - extended red emission. That's what we see around the Pleiades, for example. It's quite a strong brownish red in deep images. Olly

M81/82 might do it and the data would be useful in their own right. Olly

This is indeed surprising. Apparently it was included in the Sharpless catalogue 'erroneously' classified as an emission nebula, whereas it is now regarded as IFN. I wonder if there might not have been some truth in the original classification since you've captured Ha in a filter which would not, I don't think, pick up faint reflection nebulosity. Perhaps the object contains both ionized hydrogen and the stuff of molecular clouds? As a control, you could take a test run on some bright (or less faint!) IFN in the same filter. Olly

It's no fun if you have to struggle. Unfortunately telescopes get better as they get bigger, more or less, but two flights of stairs remain two flights of stairs. I think you made the right call. A bigger scope might come with a change of living arrangements. Olly

I never use any ready made stretch. I'll use a simple log stretch in Levels till I get somewhere on the way to a final stretch but, after that, further stretching is hand made to suit the data. Olly

Guiding errors will be consistent across the entire frame. If you have issues only in the corners or other particular parts of the frame, the problem isn't guiding. It might be coma, chip distance, polar alignment, chip tilt... It's a nice clean image but I'd watch the bright end which is slightly saturated with this stretch. If it isn't saturated at the linear stage it doesn't need to be saturated in the stretch. Olly

What makes you say the L channel is over exposed? How have you come to this conclusion? Maybe you could link to a crop around one of the galaxies in the linear L data. Don't link to the whole image, the files are too big. Olly

Absolutely not, in my case. Dust should net get into an electric filterwheel and, if it has in your case, I think you need to find out how it did so. My flats last for months. Olly

That's nice and specialized processing could take it still further. The real problem, though, is that this small part of M42 is far, far brighter than any other deep sky object I can think of. To be specific, in my own M42 I shot this region in 11 second exposures, the area around it in 50 second exposures and the rest in fifteen minute exposures. The Trapezium region is not your typical DSO! Olly

In order to edit (we tend to say 'process') an astrophoto, you'll need software. There are really two kinds, astro-specific packages and general photo-editing packages. I don't know if there are any free astro-specific packages but the obvious choice for a free generic photo-processing package would be GIMP. This is essentially a free imitation of Photoshop. More and more serious astropotographers use only astro-specific software. I'm one of those who does not. I take some initial steps in the astro-specific package Pixinsight but I quickly move into Photoshop after that. If you went with GIMP, the first thing to understand would be the Levels and Curves routine. I'm sure there will be lots of websites covering this but do be aware that some of them are totally incompetent! Olly

Noise Xterminator. It is beyond good! However, I did two other noise-related things in Photoshop for the background sky. 1) Use the colour sampler to pick up just the background sky and greatly reduce the saturation. A very obvious trick, dead easy and always helpful. 2) Zoom in to 200% or more, open Curves and find the brightest of the background pixels. Put a fixing point on the curve at that point. Put several fixing points above that to keep the line pinned straight. Now grab the curve below the original point and raise it to taste. This simply brings the darker background pixels up closer to the brighter ones. Don't overdo it. In this image, be very careful not to lift any background above the faint tidal extensions or they'll be drowned. Always do NR as a layer on top so you can easily erase it where you don't want it (though Noise Xterminator is so good that this is hardly ever necessary.) Olly

I have a Mesu 200 which easily carries a 14 inch catadioptric. (I have one on it at the moment.) I think an EQ8 would also do it. Olly

14 inch RASA. For the imager, it can do everything, widefield and high res., and do them at lightning speed. Olly

Well, I think the full set was good. Total integration time is not long by galaxy standards, especially when there are tidal tails involved, but the data were very workable. Olly

I don't believe Paz. I'm certain that it is a perfectly focused image of either toothache or a hangover. I'm going to say toothache... Olly

I can't download 300meg of data but O's post (the first response) shows an obviously better S/N in the left hand image. Maybe consider cropping the images to make file sizes more reasonable? Dark skies and poor internet tend to go together! Olly

I very much like these renditions, which have a dramatic lighting. There's a strong feeling that we're in the depths of space. I also think the colour is great. You've not been draw into overloading the blue so your colour resembles professional images. Olly

That's very classy indeed. Lovely, going from the extremely faint to a nicely judged core. Olly