From: Milton Aupperle <milton@outcastsoft.com>
Date: July 13, 2012 11:05:15 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Sun Spot Images
Hi Raye;
On 13-Jul-12, at 3:36 AM, Ray Byrne wrote:
Hi Milton and Alan,
One of my astro passions is the Sun. Since I was at high school and the school astronomical society I used to use the science labs observatory at lunchtimes and project the Sun on to the dome wall and do daily tracings of sunspot positions. Now I have my own observatory and great equipment but it seems I can never seem to achieve results like you have both got here. Well done Milton especially with such a small aperture to get such detail your scope must be performing to it's limits. I think that (correct me if I'm wrong) that the main reason that you guys can get these results is that you have had good seeing when these images were captured. I can imagine that doggedness and persistence must play its part as does good equipment that is well adjusted and clean. Also that skill and technique and knowledge of software is important too. But would you say that these images are primarily the result in the good seeing you had?
In my case, I have just had lucky seeing. The five days that I have imaged (between end of May and 3 days ago ) the sun since 2005 have been pretty good (for 1540 mm fl imaging) and one day was exceptional - which is when I shot about 40 gigs of sun images using long 3.85 meter focal lengths. On that really good day, the Sharpness graph for 5416 frames was a nearly a perfect bell curve distribution.
Normally my seeing sucks and I get huge jumps of +/- 10 arc seconds even when shooting at 0.3 ms exposures.
In case I do get good seeing sometime (BTW is the jet stream south of you guys at the moment or in a favourable position relative to your locations) can you share with me the process you use to achieve these results?
In my case, the Jet Stream was about 1000 km north of me - up near the NWT - Alberta border when I shot that detailed image. That's why we are sweltering in in 35°C heat. On that day, the NAM 300 forecast had huge swatches of bright pink lower turbulence seeing over Alberta - and most of the USA too that day. Normally we are in "blue" color which means craptacular turbulence.
I've got an old book called "High Resolution Astrophotography" by Jean Dragesco and I wonder from reading about seeing in that whether I'm unlucky enough to have permanent poor seeing due to some local circumstance. I have a very small backyard and my fibreglass observatory dome takes up most of it (well half of it). My house is only about 5 yards from the obbo and is tall as it's a 3 story town house and is part of a terrace of such houses. I only have a view of the South East and South then my house and the adjacent ones are blocking my view. The prevailing wind in the UK comes from the West so I wonder whether there are vortices caused by that wind hitting my house and flowing over it and causing local poor seeing for me. I'm surrounded by houses with concrete tiled roofs, tarmac paths and roads. It just that I never get good results no matter how hard I try when my friend Mick Hyde who live about a mile away with virtually the same gear gets great results (been published in magazines, LPOD, and even in Celestron literature). What do you guys think?
Is your friend's location much the same as your for local surroundings (roads, houses, concrete path ways etc.)? Or does he have more grass and open areas?
To the east of me, I have a large river and grass fields, directly south I have a huge (freaking lit up like the sun at night) asphalt parking lot and then grass hills on the other side and to the South West I have a 3 story metal building with asphalt roof. Because they are broad areas of similar materials, I don't get a much uneven gradient heating (areas that heat up fast like black pavement - areas that don't like grass) with local cells.
When I lived down town in an apartment with a 13th floor balcony, certain areas below me were guaranteed to have much more turbulence than other areas - especially at night when things cooled down. That seemed to be restaurants / businesses as the worst, then homes / apartments complexes and finally parks the least.
I would suspect it's local heating that may cause much of the turbulence. It might be interesting to try imaging the sun as early as possible in the morning - before stuff heats up too much too see if that helps at all.
Sorry to bore you with all this but if you could perhaps give me the benefit of your wisdom I'd appreciate it greatly.
My set-up is as follows:
For Solar work
C9.25, NEQ6, DMK21AF04 or PGR Chameleon, Baader film full aperture filter, Baader Solar Continuum Filter. I also use an 80mm PST for Ha and a Skywatcher 102mm f9 Equinox ED Apo with an Intes Herschel Wedge for white light too
BTW what is Alan's sun color schema?
It's just the color balance, which has the sun's Mono disk at about 60,000 Red 40,000 Green and 9,000 Blue for colors. Alan does something more sophisticated in PhotoShop, I just adjust the R G B balance for the whole image in Astro IIDC.
HTH..
Milton Aupperle