THE BRITISH ASTRONOMICAL ASSOCIATION

On 8 Dec 2010 two spots were recorded on Saturn at the same latitude.
Firstly, a bright spot was recorded close to the central meridian in an image taken at 02:12UT by Sadegh Ghomizadeh in Iran.

The provisional position for this spot masured from the image is:
latitude 37.5 degrees north (planetographic), longitude (System 3) 248 degrees.

Just over 5 hours later, David Gray in the UK visually recorded a light spot approaching the p. limb.
The provisional position for this spot measured from David's drawing is:
latitude of 37.5 degrees north, longitude (System 3) 29 degrees.

Observations wil be added to the galley shortly .
Saturn is well placed for observation before dawn and more observations are urgently required to confirm these features.

A number of spots have been detected on Saturn so far during the current apparition Provisional drift charts for a number of these spots have been derived from section member observations and are shown below.

As noted in an earlier news item, there has been a bright spot visible throughout the apparition in the northern Equatorial Zone (EZ(N)). The drift chart shown below is an update of that shown in the March Notes & News, and this shows the continuation of the spot's positive drift relative to System 1.

Drift chart showing the positions of the centres of the white spots observed in the EZ(N). Longitudes are in System 1.

So far, only a few observations have been made of the dark 'barge' which lies to the north of the South Equatorial Belt (SEB). However a preliminary assessment of these observations indicate that it has a very rapid positive drift of ~11 deg/day with respect to System 1. However further observations are required to establish a reliable drift.

Drift chart of features on the northern edge of the SEB. The preceding, centre and following edges of the dark barge are shown. The longitude system used for this chart is one moving slower than System 1 by 11.1 deg/day.

A white spot has also been observed in the SEB zone (SEBZ) and has a rapid prograde drift with respect to System 3 of ~7.1 deg/day as shown in the following chart.

Drift chart of features in the white spot in the SEB(Z). The longitude system used for this chart is one moving faster than System 1 by 7.1 deg/day.

Finally, the white spot which has been observed north of the South Temperate Belt (STB) at a latitude of approximately -40 degrees is showing a positive drift with respect to System 3.

Drift chart of the white spot which lies north of the STB. Longitudes are in System 3.

March 23. Here is a drift chart from Winjupos for the EZ(N) over the last couple of months and shows the movement in L1 of the centre of the major spot plus the two additional ones discovered by Damian Peach on March 3, 2009..

On the night of March 16/17 Pete Lawrence and David Arditti recorded a dark 'barge' like feature on the northern component to the SEB(N) at l3~ 187. See the Saturn Gallery. Further observations are required.

(1) One or more white spots have been observed in the EZ(N). Some images of this are shown in the 2009 image gallery.

Paulo Casquinha observed one at L1 = 88 on Jan 7 whereas Anthony Wesley and Stefan Buda observed one at L1 ~ 100 on Jan 17. More observations are required to confirm i these spots are identical.

(2) On 2009 Jan 31 the satellites Mimas, Dione, Enceladus, Tethys and Titan will be grouped within 8 arc seconds area of sky, preceeding the planet. The closest grouping will be at approximately 07:00 UT. The following diagram (oriented with south at the top) shows the predicted positions around this time.

On 7 December 2008, Damian Peach imaged two spots, one is in the STropZ and the other in the SEBZ. Their longitudes were L3=309 and L3 =281 respectively. More observations are required to track their motions.

From the UK, Saturn is rising before 23:00 UT, and reaches the meridian at approximately 5:00 a.m.

The tilt of the rings is now under seven degrees allowing more of the northern hemisphere to be visible. Some recent amateur web cam images taken from a number of parts of the world have revealed a small light spot in the STropZ to the south of the SEB at system 3 longitude (L3) ~273 at the beginning of December 2007 and L3 ~ 281 in early January. There have also been reports of a spot in the SEBZ at L3~ 98 in early January.