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Finally got everything almost working right! Off-axis guider cuts off right of frame a bit but oh well.
ED80 on iOptron CEM25 14 x 5 min guided. Then the fog came in
Was fighting dew all night but rigged up a dew strap that did pretty well!
Comments, criticism and feedback always appreciated.
I've spent the day at the keyboard documenting some image processing techniques and as the skies have been so poor, I've had to use some old data for the screen shots but this one worked out OK with the new work-flow.
A Wall of Ionization
NGC 7000, the North America Nebula, is a very popular deep sky imaging object and its rich Ha emission content makes it particularly appealing for RGB imaging. However, I like to capture this region of the Milky Way in Cygnus using narrowband filters to really bring out the detail in ‘The Wall’.
As well as the predominant Hydrogen Alpha (Ha), this object is also quite rich in doubly ionised Oxygen (OIII) emissions. The position of OIII emissions in the light spectrum, right on the cusp between green and blue, allows a full RGB colour image to be produced from just two sets of filter data by using the OIII data for both the green and blue channels and the Ha data for the red channel.
Mount: Mesu 200
Telescope: William optics FLT98
Reducer: William Optics FR IV
Camera: QSI 683 WSG-8
Filters: Baader 8nm Ha and 8.5mm OIII
Subframes: 19 x 900 sec OIII, 19 x 600 sec Ha
Control: CCD Commander
Capture: MaxIM DL
Post-Processing: MaxIM DL and PS3
I am currently entertaining myself with data from the monochrome (red or blue filter) glass plate images from the Palomar Observatory Sky Survey II (1990ties) by adding RGB data from my own images. I download the data from the Mikulski Archives site (I am sure many of you know about it but I only discovered it yesterday). They used the Oschin 48-inch (1.2-m) Schmidt camera on the Mt Palomar Obsy and I used my humble 5" ES apo refractor and Canon 60Da. Here is the download (red filter image) from the Mikulski Archives site and the final colourised version made in PS. I added the glass plate data to my RGB in PS using both Soft Light and Luminosity mixing, and then stretched, improved contrast, and worked on the colours. Much of the job went into the initial the scaling, rotating and aligning (manually in PS).
Comments and suggestions most welcome.
Despite some clouds yesterday night, I managed to get a few hours staring at the Cygnus Wall.
This is very much a WIP (am shooting more subs right now, less cloud)
So far, 17 of 31 frames stacked (only about 6 - 7 rejected due to poor tracking, the rest due to low contrast = clouds)
17 x 480 sec subs (unguided) + calibration frames @ ISO 800 (total time on target: 2 h 16 min)
scope: SW 150P on AZ-EQ6 GT
camera: Pentax K20D (not astro modified)
software: PixInsight (stacking, cropping, colour calibration, noise reduction, stretching and slight sharpening).
I may restack these with the low contrast frames to see if I can get the noise down. At which time I will also make an effort to reduce the stars and sharpen the nebula.