Out last evening (Thursday Nov 7) imaging Saturn.
This is the best image of the best 10% of 10K frames exposed at 18ms. Saturn was only 35 degrees in altitude, seeing was poor, transparency was poor and the was a crescent moon nearby in the sky.
Saturns diameter is approx 18 arcsec. This was processed with autostakkert, regixstax, gimp and imagemagick.
I can’t make out any belts or bands in the southern hemisphere and see only 3 regions in the north. Saturns shadow shows on the rings on the left side of the planet and the rings are dim.
So.. I was having to manually adjust the tracking about every two runs of 180 seconds, as Saturn (in an 800×800 cutout box, in a 1200×1200 region of interest) moved from one side of the FOV to the other. How bad is the tracking I wondered?
I know I have planned another polar align followed by a 2 star align in my TODO list.. but still what is a number for drift?
I went to http://astronomy.tools/calculators/field_of_view/ and entered my specs:
C9.25, x1.5 barlow asi585mc camera.
System FOV 0.18 deg x 0.1deg = 0.18 deg/3600arcsec/deg by 0.1deg/3600arcsec/deg = 648×360 arcsec
Camera: 3840×2160 pixels
So.. the drift of the cutout box (800×800) in 1200×1200 ROI moves 400 pixels in about 360 seconds or ~1 pixel/sec
3840 pixels/648arcsec=6 pixels/arcsec
at ~1 pixel/sec it will take 6 seconds to moves 6 pixels or
it drifts at a rate of 1/6 arcsec/second
Is that good? bad? Can others run the process for comparison?