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Tim Knutson wrote:
Lets say for a minute, that I want to go down to Home Depot and get a hydrogen alpha filter. What isle do I look in?
Seriously, tell us more about the setup.
There's an outfit called New Mexico Skies, which operates a thriving business hosting people's fancy astronomy gear, for imaging. One is in the Sacramento Mountains in New Mexico, and the other is in the South Australia desert.
In the South Australia desert, my scopes, mount and camera are located in a large roll-off roof observatory owned by NMS, with the scopes, mounts and cameras of many others. Each of us has a server, connected to the internet and our equipment; I open up a connection to my server down there before I go to bed, tell it what I want my system to do that night (what target(s), what filters and how many subexposures), cue it up, and go to bed. If all goes well (which it normally--but not always--does), it's imaging away when I wake up in the morning. I download the data from the server in Australia to my home desktop each morning, examine the individual subexposures, and file them appropriately (many get tossed as not being good enough, so the 26 hours in this image probably represents 35 or 40 hours of active data collection).
To clarify, inside the camera is a filter wheel. The camera's chip is a monochrome chip; I take images using a variety of filters: At least a clear filter (for the details), and a red-pass filter, a green-pass filter, and a blue-pass filter. Combining the images taken through the color filters gives me a true color version of the object, and the images through the clear filter gives me the detail (very much like color TV worked in the analog days, with two signals broadcast, one low resolution carrying the color information, and one high resolution carrying the detail). If the object has interesting emissions in a particular narrow band for which I have a filter (hydrogen alpha, a very narrow piece of the red spectrum, is emitted by many nebulae; I also have filters for recording emissions from sulfur ions and oxygen ions), I'll take images through those filters, in addition to the LRGB filters.
Processing is very time-consuming, and often very difficult; this one was particularly difficult, for a variety of reasons (principally, it's very difficult to blend narrow-band data--hydrogen alpha in this case--with broadband data, since the narrow-band data are so dense; so it's tricky and painstaking to do that; also this is a very nuanced nebula, and I really struggled to find what I felt was an optimal point in the sharpening curve, so that the image shows many details, but doesn't look like it has had too many facelifts). I started processing this data set in November, gave up for a while, re-commenced in early March, worked on it for many, many hours (often working myself into a rat-hole, and starting over almost from scratch).
I finally decided that this was as good as I am going to get, declared victory, and posted it.
It's a labor of love; not for the faint of heart.
Mark
Edited on Apr 11, 2015 at 01:04 PM · View previous versions
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