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Section Report June and July 2017

 As one might expect the majority of observations received concerned Jupiter, which has dominated the evening sky throughout the period. Saturn, ‘though very low for observation from the UK, received some attention especially around the time of opposition on the 15th of June, as did Venus by one dedicated observer. I will start with a summary of observations of Jupiter as seen photographically and would mention that most of the recorded features were noted by Alan heath in a series of detailed visual observations that he sent in covering the Jupiter apparition from March through to June.

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The North Polar Region (NPR) contains little detail other than three rather obvious white ovals with the brightest, NN-LRS-1 seen around L3 340 degrees, plus a chain of dark spots delineating its southern boundary. The North Temperate Belt is split into two distinct elements (North and South) with the dark grey NTB(N) barely separated from the distinctly orange NTB(S), the pair making a striking joint feature around the whole circumference of the planet. The North Tropical Zone (NTrZ) is bright but very narrow, just separating the higher-latitude northern belts from the North Equatorial Belt (NEB). This is now over 10 degrees in latitude wide and contains 3 distinct white oval storms as well as fainter features. Perhaps the most well-known is the long-lasting feature White Spot Zulu (WSZ) but this is currently marginally smaller than the other two storms, WS-a and WS-d.
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A number of large dark festoons grow into the Equatorial Zone (EZ) from the NEB such that the border between belt and zone is very disturbed and indistinct at times; ‘though this zone is, overall, the brightest on the planet at the moment. In contrast the upper edge of the South Equatorial Band (SEB) is sharply defined ‘though the band itself is very disturbed. A dark rift starts at a storm feature within the SEB just north and retrograde of the socket containing the Great Red Spot (GRS) and proceeds diagonally, north to south, at a very shallow angle in a retrograde direction around nearly three-quarters of the circumference of Jupiter: Both above and below this dark line, pale storms and turbulence rage within the belt. In contrast the remaining sector of the SEB looks relatively calm since the chain of storms reported prograde of the GRS in the last reporting period have now subsided.
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The GRS itself is reported to be a striking, deep rosy pink and contains great detail in some of the images received. Below this, the South Tropical Zone (STrZ) is broad and empty, containing only the little red spot, Oval BA, and trailing that a pale dark ghost of the South Temperate Belt, which is visible over barely 20 degrees of longitude. Further down the South-South Temperate Belt (SSTB) merges into the South Polar Region but contains 9 obvious white ovals; the extreme south, like the NPR contains 3 pale ovals to break up its otherwise uniformly grey appearance.
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Individual observations started with images made on the last day of May by Martin Lewis, and the first of June by Dave Tyler, with Martin’s image showing WS-d as a very obvious feature in both mono and colour versions.  Alexei Pace followed with images from the 2nd, 4th and 6th of June, joined by Steve Norrie on the 2nd and Dave Finnigan on the 4th. Alexei’s infrared image from the 4th shows striking detail in both the EZ and the SEB, while Steve’s and Dave’s image show the deep colour of the GRS and the distinct orange band of the NTB(S). Dave’s methane-band image from 2208 UT on the 4th shows Oval BA as a bright beacon with a white oval in the SPR also visible.
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These features are also clear in an excellent colour image taken in twilight at 2006 UT on the 14th of June by Martin Lewis. Martin had some problems colour balancing against a bright background sky but did a tremendous job to get his image. This was the start of a short period of fair seeing in June which brought in further images on the 16th, 17th and 18th from Dave Tyler, Simon Kidd, Mike Brown and Carl Bowron. Simon’s image caught very well the start-point of the disturbed area in the SEB retrograde of the GRS with Mike’s showing the emptiness of the STrZ and Carl’s wide view capturing Europa, Io and Ganymede in the frame. A final image in June, by Dave Finnigan and from the 22nd, shows all four Galilean moons strung out in the correct order, inner to outer, Io, Europa Ganymede and Callisto, all on one side.
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Only three more Jupiter images were received in July, from Martin Lewis on the 2nd and 5th and Alexei Pace on the 10th; after this the bright evening sky of summer combined with the sinking of Jupiter into the west made observation difficult. Martin’s first image shows a striking shadow-transit of Ganymede with detail visible on the moon itself; he used an infrared filter to help cut through the relatively poor seeing of a low altitude target in the evening sky. His image from the 5th nicely captures WSZ on the central meridian as does Alexei’s image from the 10th.
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Moving on to Saturn, the ringed planet reached opposition on the 15th of June and a brightening of the ring system known as the Seeliger Effect is often seen just either side of the date of opposition. Also known as an ‘opposition surge’ this happens when the shadows cast by ice-pieces within the ring system fall directly behind the object from our point of view and are therefore hidden from us; the result is a brief surge in apparent brightness. Dave Tyler took a series of excellent images starting on the 13th of June and stretching to the 20th and while he was not able to image on the night of opposition itself, his image from the 16th does show a slightly brighter ring system than those caught on the 13th, 17th, 18th and 20th. Dave used infrared images to try and overcome the problems of very low altitude presented by Saturn; overlaying this IR data onto colour images as a luminance layer, to get a final result.
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Prior to this Larry Todd sent in an image taken at the end of May from New Zealand nicely showing multi-coloured banding on the planet and with a sharply defined Cassini Division in the rings. Then, moving into July we had a number of Saturn images from Dave Tyler, Martin Lewis, Alexei Pace, Steve Norrie, Dave Finnigan and Carl Bowron. Dave’s image from the 3rd again used the IR overlay technique onto colour images to produce an excellent image, full of colour and with hints of structure down to the Encke Division within the rings. Martin used a similar technique on the 5th, capturing a view of the South Pole, just visible through the Cassini Division. Both Martin and Dave employ an atmospheric dispersion corrector when imaging, a device I highly recommend for observation of low altitude targets.
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Steve Norrie’s picture from the 8th again proves that small aperture telescopes can make good planetary images; with his usual large Celestron SCT being serviced he used a 127mm Makzutov for his image. By the 16th Saturn was a month past opposition and Dave Finnigan’s image clearly shows the shadow of the planet growing to one side of the ring system, as does those of Carl Bowron on the 16th, 17th and 20th. His wide view from the 16th captures Titan, Tethys, Dione and Rhea as they orbit the planet. Then Larry Todd sent an excellent image from the 29th containing great colour and detail as did Dave Tyler’s pair of images from the 24th and 31st showing the growth in the shadow cast by the planet on its rings.
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Venus was a bright morning object which reached its greatest western (morning) elongation from the Sun on June the third. Low elevation during darkness meant detailed observation was near impossible so Carl Bowron decided to seek the planet out in daylight. This is safe as long as you take great care to ensure the Sun can never enter the field of view of the telescope else blindness or equipment damage will ensue. His images from the 18th of June and also the 18th of July show the increasing illuminated phase and slowly shrinking apparent size of this planet.
 Finally Simon Kidd captured two images on the 31st using an infrared filter. In excellent work he shows the movement of cloud over a 76 minute period.
Alan Clitherow
Section Director.

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