15 replies to this topic

[pjr200]

At long last it looked as though the seeing was going to be good when stars close to the horizon showed very little distorstion.

As Saturn rose in altitude the cassini division became visible for long periods of time allowing small adjustments in focus to be made. This only the second time since December where I have been able to see the cassini division, every other time there was only hints of the cassini division due to a change in contrast. It had been quite disconcerting as it was making me wonder if there was an issue with my collimation but as ever, seeing is king.

Unfortunately the storm must have been on the opposite side of the planet ( typical ). Here is an image throught the red filter (Stacked about 1500 frames from 10000 frames). I did capture some RGBs but they need quite a bit of work and to be honest I'm not expecting great results as I never really nailed the focus in green and blue. I really need to do a star test to workout the difference in focus between red, green and blue.

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[pjr200]

In IR (stacked about 1500 frames from 10000)

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[Mitchell Duke]

Very Nice Saturn, cant wait to see the RGB shots!

[Kecktastic]

A most excellent result there Paul, as you have mentioned seeing really is king and even at low alts with good seeing very good results are possible and these really are very nice.

Well done.
Regards
Trevor

[Asimov]

Very very nice. Love that second image!

[ZielkeNightsky]

Great images.

The second image is very nice.

Thanks for sharing

[pjr200]

Thanks for the kind words everybody

Not much luck balancing the colours for the RGB at the moment although I'll going to give a few more goes.

[Freddy WILLEMS]

10000 frames ? How much was the image run ?
Great Saturn BTW.

[Mick Hyde]

Excellent work Paul. The new scopes really cooking ;-)

[pjr200]

Thanks Freddy

Seeing as though I was imaging the boring side of Saturn I thought I would go for some smooth images although this would of course blur any minor details.

The data for red filter image was recorded over 5 mins and 24s (5 avis, 2000frames each at 30fps). Looking at Neil Phillip's images on stargazers lounge I think we both caught a small storm (which is on the left hand side of my image) although my red filter shots were taken about 20 minutes later. At some point I'll select 3 of the avis and reprocess to see if it is just a processing artifact.

The IR image was recorded over 11 mins and 5secs (5 avis, 2000frames each at 15fps).

The RGB shot below was just 3 avis recorded over about 4 minutes. Not great as both the blue and green images let me down. I think I need to find how far away the focus is between the filters using a star.

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[pjr200]

Thanks Mick
I'm really starting to like the scope. I was starting to get a bit paranoid about the collimation as my recent results on both Jupiter and Saturn were quite poor even in IR. It seems to be that the UK has had some very poor seeing especially at the lower altitudes where the planets are poorly placed.

[DesertRat]

Very nice Paul. Well done!

You mentioned "I think I need to find how far away the focus is between the filters using a star." I don't think the filter offsets will be very large in that scope, certainly less then a SCT. But determining them on a star can be difficult in average seeing, a FWHM program or similar program like Metaguide might help. I found the best technique is to use the Moon. Find an area with some fine craterlets, get best focus in red, call that your zero point and proceed to green and then blue. It seems an extended object with lots of contrast is very sensitive to focus and the eye can integrate all the detail in an area pretty well. This procedure can be performed in average seeing, although better seeing is preferred. This should be done in a stable temperature regime (or done with dispatch), as the offsets are similar to what one can see over 15 minutes of cooldown!

Cheers,
Glenn

[pjr200]

Thanks Glenn

Many thanks for the suggestions. The Moon sounds like a very good idea.

[Mick Hyde]

Nice colour Paul. Did you use the IR in the lum channel?

[pjr200]

Thanks Mick
Its just a normal RGB without lum channel. Here is the same image using the red image as the lum channel. I alwys find the colours quite difficult when using a lum channel although they always have much better sharpness.

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[john rozakis]

Excelend work Paul . Ir is very good !