Saturn June 25 - equatorial spot drift measurements
Hi
had a short break between rain and the seeing was above average. The break came out of nowhere and there was no time to collimate (went with the basic laser collimation) or to cool the scope properly, so the results were better than expected.
This also provided another look at the equatorial spot mentioned in earlier threads. Along with Damian Peach's image of the 19th (link in previous post, thanks Trevor), there are now 4 images showing a spot in the same general region over almost 3 weeks from June7 to June25. I plotted out the WINJUPOS system 1 longitudes vs time and there seems to be a reasonable argument that it is the same spot drifting around the planet at an almost constant rate of about 28 kph relative to system 1 (the spot is moving against the planet's rotation). Either that or the system 1 rotation assumption (10h 14m) does not exactly describe the current actual rotation at the spot latitude (between 6 and 9 degrees North) of 10h 14m 28s. It also appears to have a slight Northwards drift, consistent with true motion. The spot is not particularly bright or large (looks like it would fit within the Cassini division at ~4700km - many times larger than hurricane Katrina), but it is persistent and has been a lot of fun to hunt down.
the greyscale spot images have been excessively processed to enhance the spot, but it can also just be seen in the colour image.
hi Matt. thanks for the comment. It is fascinating that we now have tools sufficient to do basic measurements of the motion of a fairly ordinary storm on Saturn, using equipment hastily set up in the driveway of a suburban house. regards Ray
Well done Ray, very interesting latitude for this spot, the winds in this region approx the speed of sound and yet this feature seems to have survived for at least a couple of weeks.
It certainly is interesting to speculate on how a spot might survive in the extreme winds of the equatorial zone. This spot has not changed much in appearance in nearly 3 weeks (maybe slight elongation in the last image), so it is presumably being carried along as a coherent structure embedded in the moving "surface" - and moving at close to the system 1 wind speed. This is not without precedent though - a BAA report on a 1994 equatorial spot noted " The spot therefore seems to be a long-lived phenomenon with no significant change over the past tens of rotations." http://www.physics.sfasu.edu/astro/saturn/spots.html
Other equatorial spots have rapidly elongated, so I guess there must be more than one formation mechanism.
regards Ray
Nice work Ray
Both with the images and the investigation.
Even with such a small data set the correlation looks good
Sorry that I haven't been able to contribute data, a combination of bad weather and a shortage of time have kept me away from imaging for a while
Nice work Ray
Both with the images and the investigation.
Even with such a small data set the correlation looks good
Sorry that I haven't been able to contribute data, a combination of bad weather and a shortage of time have kept me away from imaging for a while
thanks Rob. would be really nice to get a few more independent images to make sure that I haven't stuffed something up.
Quote:
Originally Posted by von Tom
Excellent work Ray - fascinating.
Tom
thanks Tom
Quote:
Originally Posted by Lester
Thanks for all the info and images Ray=amazing stuff. All the best.
Ray, thank you so very much for sharing these pictures and information. I saw Saturn through a telescope for the first time this year and cannot wait to capture it for myself, shots like yours inspire me a great deal.
