Thoughts from Starlight Cascade

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?

copyright StarlightCascade Observatory

Wow.. a cold cold night! was -5C and a bit more at various times.

So.. This is Saturn from just after the CFL West semifinal where Sask prevailed over BC. Yay!

This is the best 10% of 10K frames of 20ms exposures with Saturn very near the meridian. Earlier that day I also did a firmware upgrade of the skywatcher synscan hand controller… jumped up three versions and the upgrade process went well. Always a dicey decision.. firmwares have been known to brick items.

The dew strap around the corrector and the dew shield worked well. no fogging or condensation of frost on the glass all night (I packed it in around 1am.. more on that in the next note about Jupiter and the Ganymede shadow transit). This processed image was taken around 2146 EDT. The altitude was fairly low at 36 degree but I did not really see any atmospheric dispersion effects. The rings are getting dimmer and harder to make out. The moon Titan was well out of frame last night as well..

autostakkert! registax and gimp processed.

This is the 54th imaging session of 2024 in the Serenity Observatory at SCGO.
This mornings three imaging runs of Jupiter occurred in nice warm 15C weather but with a wicked wind of 7kph gusting to 20kph.
It was supposed to be over 50% cloud but we got lucky with a clear hole in the clouds for an hours or so.
Today is also the first foray into more advanced image processing.
So far we acquire a video file of thousands of ms exposure frames, open that in Autostakkert! v4 which sorts them by quality and aligns and stacks them. We generally go with the best 5% or 10% of 15K frames.
Then we take that output and put it into Registax for wavelet processing and RGB colour balance. We get a much sharper image out of that process.
Today I downloaded Gimp 2.10.38 (a free image processing program similar to photoshop) and brought the images (.png format) in one by one and applied some very basic operations on them:
1) colors, levels, black drop, applied to the background and then to the faint processing artifacts of a light ring around the planet. It disappears.
2) colors, saturation, scale up to x1.5
3) filters, enhance, unsharp mask, scale up to x1
export as .png
THe first image on the left is the “regular” autostakkert and registax output. The 2nd image, on the right, is the GIMP enhanced version.

I can certainly see a difference in the two and consider the GIMP enhanced one a value added image. However there is sooo much more to learn now!

Mars is now high enough to be out of the goop and is starting to show some nice detail.

This is the best 5% of 15K frames exposed at 1ms each using an ROI of 1200×1200 and a firecapture cutout of 800×800.
The northern polar cap is seen with the planet showing 9 arc seconds of diameter. Some darker area north of the equator and lighter areas south. Using Sky & Telescopes Maps previewer, I could not actually match any features.
Mars altitude was 65 degrees high.
These annotations are incorrect as they state the OTA was the Vixen VC200L. This was actually the Celestron 9.25.. have to update the scripts and reprocess the annotations.