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Observing Jupiter by John Fletcher @ Mount Tuffley Observatory UK.

Jupiter is a planet that can be observed for around 9 months of the year given a clear horizon.
At Western quadranture ( 90° West of the Sun ) it is on the meridian at sunrise.
At Eastern quadranture ( 90° East of the Sun ) it is on the meridian at sunset.
The very best time to view Jupiter is at opposition ( 180° from the Sun ) when it can be viewed all night long.
Due to the flattened polar regions the Polar diameter is somewhat less.

Small refractor telescope of only 3 inch diameter will show the dark belts and bright zones.See my picture of Jupiter taken with an F6.3. 8 inch Newtonian.

Now most serious amateur astronomers use a 6 - 12 inch reflector, and telescopes in this range will give research capabilities on the planet Jupiter.Serious research can be made using 10 - 12 inch Newtonian reflectors or larger and will permit one to carry out advanced programs and excellent photographic studies of the planet. With this type of research in mind it is important that the focal ratios should be at least f6 ( better if f7 or f8 ) The longer focal lengths will produce a larger primary image at the primary focal point.The other thing to remember with reflectors used for planetary research is to keep the diagonal mirror ( flat ) as small as possible for higher contrast planetary images. If one wants a more compact instrument the f10 Schmidt-Cassegrain high quality reflectors available are ideal instruments.

Another important thing using Newtonian reflectors is to ensure that the alignment ( collimation ) of the mirrors is correct and that high quality eyepieces are used such as good Orthoscopic and Plossyl's. The ones I use are made by Celestron and are excellent.
You should also try to keep the tube currents and temperatures inside the tube assembly, including the mirrors the same as the outside air temperature. If you store your telescope indoors when not being used, uncover it and wait 30 minutes for it to adjust to the cooler night air at your observing site. If stored outside permanently 15 minutes should be long enough for things to adjust in Winter. Be aware though, in Summer months an observatory can become very warm inside and the telescope may take 60 minutes to cool to the night air and stabilize inside its optical tube assembly.

The final link with observing any planet is the observers eyes. Only by persistent observing and patience will the observer become an experienced observer. The beginner at first will only see the cloud belts and will have great difficulty in seeing the structural details of the belts and zones. After many weeks and even months of continuous observing one will be able to detect the many observable features such as dark spots, festoons, garlands, streaks and bright ovals.
A comfortable observing position and "The trained eye" linked with a steady Earth atmosphere ( good seeing ) is most important to record fine details of Jupiter's upper atmosphere.
Drawing the planet
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First one must draw the details seen within a 10 minute period. Due to the rapid rotation of the planet features move from the centre of the disc to the edge in only 2½ hours. Until you become quick and experienced, and especially if you are not an artist it is much better to draw parts of the disc. One could concentrate on say, one of the many belts or bright zones for a 10 minute period. Detailed renderings of local areas are more often far more accurate and valuable than full disc drawings.
A long "strip sketch" of a narrow section of latitude can be added to as Jupiter's rotation brings successive longitudes to the central meridian. One of the most important type of work that the amateur can do on Jupiter is the recording of central meridian transits of markings visible during the period of observation.
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Don't make a sketch unless the seeing is good and adequate detail is observed.
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Sketch the larger and more prominent features first, then place the smaller and minor features relative to the larger ones. Also ensure that you position the belts correctly in latitude and relative to each other. For example: place the South equatorial belt at the proper distance from and relative to the equator. It is most important to draw features in their proper sizes relative to the disc and other features. Also shadings and contrasts can be made using pencils of varying hardness.
When you become even more experienced you may wish to make intensity measurements. The standard intensity scale applied to Jupiter is the A.L.P.O. scale 1-10. - 10 is brightest - 0 is blackest.
9.5 for general brightness of very bright zones.
9.0 for normal brightness of the low-latitude zones.
7.0 typical brightness of Polar zones.
4.0 as average brightness of the NEB and SEB during periods of normal activity.
2 - 3 for small dark condensations within the belts.
1 for satellite shadows on Jupiter's disc.
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Finally experiment using different powers of magnification. Use the power that gives the best definition that the observing conditions will permit. Also use averted vision for seeing fine detail in small areas of activity and interest.
Personal Note: JF.
The fascinating hobby and science of astronomy would not exist if it not were for the active observers of present time and the past. There would simply have been no discoveries or anything to talk about.

I do urge you all to take the opportunity to regularly view this mighty planet Jupiter.
A few half-hours observing a week, for a month or two would give you that trained eye for observing the many features or disturbances, including the changes in appearance of the equatorial belts.

I feel these views at the eyepiece are often the most rewarding and pleasurable sights one can gain from amateur astronomy.

You to can capture that wonderful feeling Galileo must have experienced when in year 1610 using a small 30 mm telescope he discovered a Solar System in miniature. You to can observe these 4 Jovian Satellites orbiting Jupiter as tiny points of light by simply using a pair of binoculars held steady.

Clear skies John F...M.T.Obsy.