Saturn report

Saturn report

by Ralf Vandebergh

NEW:

May 6 , 2008; Great activity has burst out within the South Tropical Zone of Saturn.Already for several months,there exists a moderate bright spot within the STrZ,comparable with the one as tracked early 2006,although the spot reached probably never the brightness of the 2006 spot.Cassini scientists register radio waves(electrostatic discharges)since Nov 27, 2007.Later,a storm was found by the visible cameras of Cassini.Recently,a second spot occured following the older storm.This newer storm exceeds the older one in brightness since a few weeks.Observations on May 6,taken with the Reflector in moderate seeing and in the red light,show that these storms are actually only the brighter parts of a larger active field in this Zone,which is known as 'storm alley' by the Cassini scientists.This band is located at about 30 to 35 degrees south latitude.It is known as the STrZ for most ground based observers.

The animations especially show nicely that the brighter spots are actually parts of a very activy region.Note the 'wavy' shape of almost the entire visible band,caused by the shapes of these storms.The following images are all taken at 610nm and are partially presented as a negative to show some detail better.For more info about these storms and about pro-amateurs cooperation in this area see:

http://ciclops.org/view.php?id=4963&js=1 and http://www.jpl.nasa.gov/news/news.cfm?release=2008-069

(May 23, 2007; 20:34-20:38 UT (CM3=344-346)2 typical SEB-s dark spots with one close to the CM at L3=340.Second spot F. of it,with comparable size and appearance.This was the last observations of this apparition.It´s interesting that this kind of dark SEB-s spots are observed only begin and end apparition.

May 05, 2007,20:44-20:49 UT CM3=158-161)At the rotational p side,one of the dark SEB-mid/south dark spots is visible,as well some weaker structures in the SEB.Image at left: with arrow,in the mid: higher contrast,Right; enlargement;

April 27, 2007; At least 2 dark spots are visible at the south-side of the SEB.They tend to give the SEB-s a structured appearance.Especially the more-frame gif (below,right)gives a remarkable view.This type of spots seems first observed since early apparition (Nov 7, 2006 and some smaller SEBs spots until in December)with approximately similar type disturbances,also with one bigger spot as part of a group.Obvious is that they are observed very early and late in apparition only,with a relative steady and quiet SEB in mid-appariton and during opposition(aside the mid-SEB white spots).

Below; (partial)enlargements of the April 27 red light shots,but this time more saturated in contrast, show the more cloudy character in the concerning region.Very interesting is the comparison of the north with the south side(south is up)in which the northern SEB part looks clearly more flat,against a 'cloudy' south-side.

Red light observations on April 22 show again a big-sized white spot within the South Temperate Zone(STeZ).It looks very similar in size and appearance to the feature found on April 15,but the spot's longitude is very different what indicates a great drift.(R 610nm filter):

Click here for an overview of both the April 15 and 22 observations of this remarkable spot: http://www.kk-system.co.jp/Alpo/kk07/s070426rp1.jpg

April 17; 2 dark spots show up in the images,they appear at the same longitude in the region between L3=2-3)in the SSTeB(or SPB)and the STeB,see animation.Single small dark spots or condensations in the STeB seem well represented this apparition:

A definite big white spot located in the South Temperate Zone(STeZ) appears in the red light images from April 15.The spot is very easy visible in all of the HC 610nm shots.Big spots at these high latitudes seem rare.(CM3: 143.8-157.3 /20:44 UT-21:08 UT/ATK-1HS-11/R 610nm).

Images obtained on April 10, 2007(CM3=92-105) show definite cloud structure, in the Southern part of the Equatorial Zone(EZ),visible moving clearly with the rotation in the animations below.The turbulent shape of the EB as reported earlier,seems to be connected with this activity within the EZ.North is up this time(R 610nm images taken with ATK-1HS-11);

Overview of observations of small dark spots,condensations or disturbances in the SEB,during the months November and December.All the reported spots did move with the rotation in animations.Some notes: The SEB-s, southern part of the SEB,and bordered to the STrZ,seems to be the main place for the emerging of these spots,concerning the SEB and generally.Another remarkable note is that these spots seem to appear mostly in groups.The overview shows that they appear over the whole length of the Saturn globe,although the biggest and most interesting spots are found at a certain region of longitude.At that time around L3=290.Unfortunately,the weather conditions did not allow further observations of this longitude,to determine a drift rate:

http://www.kk-system.co.jp/Alpo/kk06/s061226rp.jpg

Color result from Dec 22, 2006.Taken under conditions varying from fair-good to very good.Obvious is a clear cyan color of the STeZ which is nice contrast with the South Polar Region at the southern side,and the STrZ at the other side.Lr-RGB image with ATK-1HS/Tcam PCVC750k):

recent observations of spots; an overview

spots in the EZ / EB / SEB / STrZ / STeB

The objects we detect within the cloudbelts and zones of Saturn are generally similar to those we see on Jupiter,although the appearance of the spots and other features is a bit different.Another important fact is the much lower contrast of the atmospheric structures on Saturn especially due to the more prominent atmospheric haze,makes them more difficult to detect.Connected factor is the lower albedo of Saturn due to the larger distance to the sun, and the smaller angular diameter of the planet due to the larger distance to Earth.

Recent observations of different atmospheric features can be found on the following pages:

White spots: http://ralfvandeberghplanetaryimages.come2me.nl/index.php?id=348829

Dark spots: http://ralfvandeberghplanetaryimages.come2me.nl/index.php?id=348842

contact: ralf.vandebergh@home.nl