All these pictures were taken at prime focus with a 10 inch Meade LX200 GPS telescope and a Logitech Quickcam Pro 4000.

This is what I call a 'quick and dirty' webcam experiments webpage.

So you will not find my prettiest pictures here, but experiments I did.

Here are the reasons for posting these quick and ugly pictures on my website as well.

Ramblings to figure out exposure times required to determine max. Jupiter exposure time before its axial or field rotation becomes a problem.

Jupiter rotates about 0.1 arcsecs per 20 seconds. That is 0.3 arcsecs per 60 seconds.

My 10 inch can resolve 0.45 arcsecs theoretically. So in 80 seconds Jupiter's axial rotation will smear its image 0.4 arcsecs.

So 80 seconds is my max. exposure time in PERFECT seeing conditions. Average worldwide good seeing is around 1 arcsec. So I can expose for 160 seconds in average seeing, nearly 180 seconds - 3 minutes.

Last night my Jupiter images smeared at 3 minutes, so that must??? be caused by field rotation.

Based on other calculations I did - will explain in detail at another time - says that at worst, Jupiter's image will rotate at a rate of 0.25 arcsecs per minute. So after 3 minutes that becomes 0.75 arcsecs.

Based on my pics of last night, Jupiter rotates on its axis in a clockwise direction on the images - and the field derotation happens in a counter-clockwise direction.

Bad news, since after 3 minutes one pixel on Jupiter rotated 1 arcsec clockwise (axial rotation) and 0.75 arcsecs counterclockwise for the field rotation. So the first image and last image of this 3 minutes show this pixel roughly 1.75 arcsecs separated.

So VERY roughly speaking, I think I can expose for 1 to 1.5 minutes - must experiment around these times.

Also roughly speaking, the moon does not have the axial rotate problem, so it can be exposed twice as long as Jupiter. However, the moon is MUCH larger angularly, so maybe the same max. times apply to it. Only experience will tell.

These calculations might be wrong, but at least give me some pointers to get me started tonight.

Only processing done: K3 ccd tools stacking and unsharp masking.

6 June 2004 at 18:00 200 of 295 images stacked 60 seconds at 1/25 sec	6 June 2004 at 18:04 200 of 295 images stacked 60 seconds at 1/50 sec	6 June 2004 at 18:07 200 of 295 images stacked 60 seconds at 1/100 sec

Shorter exposures lead to more detailed images because atmosphere turbulence is frozen, and telescope and mount vibrations less obvious.

However, longer exposures give brighter images - easier to focus.

Only processing done: K3 ccd tools stacking and unsharp masking.

6 June 2004 at 19:16 200 of 295 images stacked Frames captured at 4 fps	6 June 2004 at 19:19 450 of 595 images stacked Frames captured at 10 fps

Results inconclusive. The 6 fps AVI dropped too many frames, and looked like the 4 fps AVI. AVIs captured at more than 5 fps compresses the frames. The 4fps pic looks better than 10 fps, even though 10 fps captured twice as many frames in 60 seconds.

For the images below I captured frames of Jupiter for 3 minutes. I then processed only a subset of those frames, as if the total exposure time were, 60 seconds, 90 seconds, etc.

Taken using Meade 2x Barlow lens.

6 June 2004 at 19:10 208 of 261 images stacked First 60 seconds' frames used	6 June 2004 at 19:10 313 of 391 images stacked First 90 seconds' frames used
6 June 2004 at 19:10 521 of 652 images stacked First 150 seconds' frames used	6 June 2004 at 19:10 628 of 785 images stacked All 180 seconds' frames used

Based on this test even 90 seconds is too much (using a 2x Barlow), since the 60 seconds exposure looks much better.

Also based on my calculations above, it would have been impossible to see axial rotation smearing after 90 seconds in PERFECT seeing conditions. ( In 80 seconds Jupiter's axial rotation will smear its image 0.4 arcsecs. 10 inch telescope resolution 0.45 arcsecs )

Obviously the seeing was not perfect. I judged it to be 5/10. Lets say it was 1 arcsecond seeing. So axial rotation smearing would only have been a problem at 180 seconds.

So my somewhat dissappointing results are caused by the fact that I do not have a wedge which caused field rotation.

Even in perfect seeing I would have been able to capture for 90 seconds with no smearing, but now I am limited to 60 seconds. Might not sound like much, but that is a 30 percent shorter time.

Since the seeing is not perfect I could actually capture for 120 seconds - twice as long - which will give me twice as many frames to pick from when stacking. Roughly speaking??? images will be twice as nice with twice??? as fine detail.

6 June 2004 at 20:41 Auto picked best frames 400 of 600	6 June 2004 at 20:41 Individually picked best frames 400 of 600

2 Minutes exposure time. 1/10 sec indiv. exposures.

Large ugly rings seems to be caused by unsharp masking. I will investigate if deconvolution or wavelet processing looks better.

K3 ccd tools, or any other tool, is not perfect in picking the best frames to stack. Picture on left k3ccd tools picked the best frames.

Picture on right - I handpicked 397 out of 595 frames - took 15 minutes. So for your best pictures I suggest go and hand pick EVERY frame - it is worth it.

The only pictures I took of the moon were done at 15 degrees ALT and 25 degrees ALT.

Done to figure out the lowest altitude where imaging is still worthwhile. 15 Degrees is hopeless, the same for 25 degrees.

I did this to figure out how much time is left this year to take good pics of Jupiter.

Here is Jupiter's altitude at 19h00 at night local time.

• 6 June - 52 degrees
• 16 June - 48
• 30 June - 40
• 6 Jul - 37
• 16 Jul - 31
• 30 Jul - 15

So I have maximum I month left. After that Jupiter quickly 'sinks' too low.