View Full Version here: : Saturn Aug18 variable seeing
19-08-2012, 06:16 PM
I was very pleased to get this image. There was a 5 minute gap in the clouds - not enough time to fine tune the collimation or to insert and align the dispersion corrector, so the result was pot luck. High level thin clouds messed up the signal levels for the green and blue sequences, but the red channel was fairly good and there was just enough data to put together a reasonable RGB. The storm remnant ribbon seems now to be less distinct than earlier, but the southern hemisphere has developed a quite intense blue/green zone.
Looked forward to the usable seeing continuing for Jupiter the next morning - woke up to fog. Thanks for looking. Regards Ray
19-08-2012, 07:21 PM
A great result all up! I hope the fog clears for you soon!
19-08-2012, 07:35 PM
My goodness Ray, a five minute burst like that certainly produced the goods, I'd be very happy with that.
20-08-2012, 07:56 AM
Spectacular Saturn you got a very good image with Saturn so far and low.
Here in Italy is impossible to have image Too low in the SKY.
20-08-2012, 09:24 AM
Very nice Ray for an image late in the apparition.
20-08-2012, 10:45 AM
Hi Matt. thanks - the fog cleared, but the clouds are back
thanks Gary - yes, I am happy with the result, all considered
Thanks Giuseppe. It is still at reasonable altitudes down here.
20-08-2012, 10:47 AM
thanks Paul - still worth trying, but it is a bit hard with the current pesky clouds.
20-08-2012, 09:41 PM
Very nice Ray :thumbsup:
21-08-2012, 12:46 PM
Very nice work Ray, the conditions seem to have conspired against us for the last Month so it is important to take whatever opportunities that are presented and you have done very well with this one. Top Stuff.
21-08-2012, 01:11 PM
Hi Rob. Thanks
Thanks very much Trevor. yep, its been trying to say the least.
Very impressive. As I am only a novice I am curious to know how you achieved such a large clear image of Saturn. Could you provide a short description of the equipment and techniques you used.
I purchased a second hand Meade 10" LX200 back in May and I can only get images of Saturn that are about one third the size of your image and nowhere near as clear. I would like to have a couple of more attempts before Saturn disappears from the evening sky. The Meade has a focal length of 2.5 metres.
22-08-2012, 10:53 PM
the scope is a modified 300mm GSO Dobsonian and the overall setup is described in http://www.iceinspace.com.au/forum/showthread.php?t=85990
Your Meade should do pretty well. With typical planet cams, suggest that you try to work at between f20 and f30, so suggest that you use a good 2-2.5x Barlow to get the image scale up.
I have an RGB filter set with a mono cam, but others get good results with colour cams - take your pick. The key here is to use one of the modern high quantum efficiency cameras (eg the TIS618) which allow you to use high framerates. I usually take 2 minutes per channel at 30fps R,G and 15fps B and the short exposure times allow relatively sharp imaging in moderate seeing conditions.
Issues that you have to get right are the scope collimation and it's thermal equilibrium with the ambient air - hi res imaging is not possible unless you have these under control. The other biggy is the seeing and all you can do is work around that by imaging when the seeing is OK.....Right now, you are under a heavy jetstream, so will have poor seeing. http://www.bom.gov.au/australia/charts/viewer/index.shtml?type=windbarb&level=200hPa&tz=AEDT&area=Au&model=CG&chartSubmit=Refresh+View you need the 200hPa winds to be below about 50kts for really hi res (as a rough rule of thumb).
Stacking/processing is either Registax6 or Autostakkert2 - both are good. I use IRIS to combine the RGB frames, but other software does the same. If you already have some AVIs taken at f10, try using drizzle stacking in either Registax or Autostakkert to increase the image scale and possibly improve the final resolution a bit. If you need more info on planetary imaging and processing there are some good articles here http://www.iceinspace.com.au/projects.html
If you want more detail on anything, please ask.
Thanks Ray - Will follow your directions.
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