Have been monitoring tonights forecast conditions via CFN for a few days and does look very promising for some steady seeing. The Red Spot on Jupiter as it gets dark and a shadow transit of Io from 7:41pm EST. Mars and the Moon will be great to have a look at and / or image. Need to make some room on my laptop hard drive for tonight.
Maybe some bright double star hunting later, once the planets have gotten too low.
Seems like the local geography had won again, despite Marc and Alex saying they had steady conditions the skies down here were not steady. Has to be something to do with the air flow over the Illawarra Escarpment. Lucky to be 5 / 10, have about 25 Gb of video files that I took of Jupiter, Saturn Mars and the Moon and the images are shimmering around madly.
Haven't processed anything yet but hopefully will get some reasonable images. Glad some of you got good to excellent seeing conditions.
Jeff, seeing slowly improved during the night. I was using a scope that I'm currently star testing and this night was a great test. Cracker of a scope - I managed to see details around 500m in size on the Moon. Previously with the orange tube C8 I had I could manage just down to 1.5km. 500m is roughly 0.3" of arc. Damn near peed myself!
PS, I looked up the resolution limits for an 8" scope. What I quoted at 0.3" seems way too small! I came to this size by identifying some of the smaller craters that have a dimension given in Virtual Moon Atlas. I was then able to see much smaller craters beside these of known dimensions, and the shadows involved deduced their size, and hence came up with the 500m size. Simple trigonometry using the distance to the Moon as 384,400km, and I came up with 0.3".
Last edited by mental4astro; 22-09-2018 at 12:58 PM.
Well anywhere in Sydney beats stargazing where I am - on top of Huangshan in Anhui province, China.
The hotel is at 1570 metres with the nearby peaks at 1800m and in the clouds most of the time - which form faster than you can find your camera.
Although it’s a long way from a large city (by Chinese standards) the night sky is pretty woeful - and the usual planets barely scrape 45 degrees elevation crossing the meridian according to Sky Safari. Hence it’s quite clear astronomy is not a viable hobby in Chiba.
As it’s the moon festival weekend the hotel is also surrounded by campers who have lugged tents up here.
Well I'm glad it was good for you guys because it was awful here ��
Mark, I've been in your boat too. A mate of mine living in Killata calls me saying seeing is a corker, I pull a scope out andx seeing is abysmal where I am in Maroubra
Been like this much of this year. Good seeing being very localized. This year moire so than in other years. Very warm winter days and then very cool evenings is one source of our grief, and couple it with local geography, and it plays havoc with seeing. I'm overjoyed to have jagged a couple of nights of good seeing. No idea when the next one will happen.
Only thing things to do is keep an eye on weather patterns and look for markers that show clear skies and good seeing, and to keep trying with the scope.
Oh, don't forget, the bigger the aperture the more susceptible it is to poor seeing. There's a lit to be said to keeping two scopes, one large and one small - conditions are not flash, the small scope is King. Conditions good, the big scope claims the night. I have a modest ED80 for this when the Big Cat cannot venture out for a kill.
There is one other factor to seeing stability in a scope - optical quality of the instrument. Premis is a simple one - if all the photons are being put where they should go, then if seeing is not ideal then the image won't shimmer and blur as much, more "waft" like a flag in a gentle breeze. If the optical quality is not there, the image will waft more violently and there will be an intense shimmer in the image as the misaligned photons are thrown all over the place.
Alex.
Last edited by mental4astro; 23-09-2018 at 09:36 AM.
During my recent lunar imaging sessions, I noticed that at least 3 different components to seeing as viewed on the computer screen as I watched an AVI being recorded.
The main component was a whole-of-image wavefront, where it was as if waves of long wavelength and low amplitude were washing over the scene. Small craters would have defined edges and then soften but never smear.
Then there were bouts of localised high frequency disturbances that would destroy all the fine detail for several seconds at a time.
The 3rd less frequent component was as if a heat plume had passed over the scene and the whole scene was washed out, a bit like applying a Gaussian Filter set to 50 or 100 across the whole frame. I looked up and there was no obvious source to this, e.g. my body accidentally passing near the open end of the OTA, a low jet flying over our house, etc.
So, when combined, the effect was that at times the seeing could be estimated at maybe 7/10 but with the other effects adding to that, it was reduced to maybe 5/10.
Well I'm glad it was good for you guys because it was awful here ��
Bummer!... and you're not that far from me either.
Quote:
Originally Posted by Dennis
Hi Marc
That is a wonderful Mars image, the detail looks very fine and natural.
Cheers
Dennis
Thanks Dennis. I went to astrofest hoping to get some good shots of Mars and came back with a blurry disk because of the storm, tried from home and in 5 min got my first decent shot but it's getting small. Missed it by thaaat much.
Quote:
Originally Posted by mental4astro
Here's Friday night's effort, the curiously elongated Schiller and surrounds.
Think it must be pretty localised Marc dosent take much to throw it off. Lucky I've got a lot of good Mars images for the year but I want to push the c11 to see what it can do.
Think it must be pretty localised Marc dosent take much to throw it off. Lucky I've got a lot of good Mars images for the year but I want to push the c11 to see what it can do.