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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.
Another late night with true darkness happening about 11:30pm and the Milky Way shone brightly. The view of "our" object can be simply amazing and I saw a new projection (to me) or "arm" up into Cepheus just before the Cygnus rift- Cepheus in this area was strewn with stars and "nebulosity" naked eye. Opposite the Cepheus arm there was another shorter projection of the Milky Way and they both were very sharply defined.
The Milky Way being so bright might explain something that I see and puzzles me... I see an underlying "texture" to the sky in most places and in particular right in the MW- I'm leading into how the objects listed looked tonight to put things in context. The wide field of the SW120ED/42mm LVW only enhances this phenomena and also allows me to see...
Scarp15, who also has an interest in neb hunting asked about a few nebs he is seeking, so first off I wanted to try IC 5068 near the Pelican in the NGC7000 area. I have studied this area quite a bit and have seen IC 5068 before, but the thing is that the whole area is surrounded with that underlying "texture" blending into more visible nebula- and lots of them, IC 5068 being one. The SW120ED gave a fantastic view of the Pelican, showing its head and a few detached nebs around it, the NAN was "bright", surrounded in places by dark strips of sky.
So, once that extra wide view panned the NAN, a dark lane on the back of the neb was noticed- opposite side of the Gulf and Pelican and just past this a huge liquid shadow came into view...I followed it up down and sideways, at first I thought it is an extension of the NAN but I don't think so. I'm trying to find this oblongish patch on the maps and in images- so far only the rift really shows. However the nebula is distinct and separate from NGC7000, this was my prize of the evening!
I had seen hints of it in the dobs but the FOV was too small.
Another favorite and a goto object of mine. It showed well in the frac, both with the UHC and the Hb with a totally different perspective than in the dobs, the VX10 shows this one best perhaps but that wide FOV is riveting. In dark skies this object is not hard, harder than the NAN though.
My suggestions to anyone who wants to maximize their views of IC 5068 and area would be: use a low exit pupil 5mm-6mm+, make sure your FOV is big enough-2" widefields shine for a lot of this stuff and finally- try the "big 3" filters (UHC,Hb,OIII), it's amazing the different presentations they offer in this area- and what pops into view with each one.
Actually this is what I do and use on most nebula and this enables even modest aperture scopes like the SW120ED to give some fantastic views, from dark skies.