Jupiter Images
Theory of some Jovian features
Drawing
Filters
Transit Timings
 

I obtained these images of Jupiter with a 31-cm Newtonian (12 inches) at between f/28-f/30 and a Phillips ToUCam Pro webcam and Lumenera SkyNyx 2.1M camera. I used eyepiece projection with a 9-mm Nagler eyepiece for most of the Jupiter images. After aquiring the AVI of Jupiter, using QuickFocus or Lucam Recorder, I used Registax to select and stack frames from the AVI. I used the wavelet filters in Registax, and unsharp mask filters in Photoshop, to sharpen the image. I also used the following filters; Custom Scientific 889+/-18 nm filter, Schuler UV pass, and Baader Planeterium IR pass filter.

Jupiter in 2007

February 10 2007

February 18 2007

February 23 2007

STEREO 3D Movie 2 Mb AVI

March 3 2007

March 9 2007

March 9 2007

Methane Movie March 9 2007

March 16 2007

March 29 2007

NTB White Spots April 5 2007

NTB White Spots April 5 2007

NTB White Spots April 5 2007

NTB White Spots April 18 2007

NTB White Spots April 18 2007

NTB White Spots April 18 2007

Jupiter in 2006

June 4

June 25

Jupiter in 2005

A Cylindrical Projection Map for February 2005 - 642 kb

Feb 15

Feb 16

Feb 18

Feb 20

Feb 22

Feb 15

Feb 23

Feb 26

March 4

March 5

March 7

March 14

March 16

April 3

April 19

July 1, 2005


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Theory of Some Jovian Features

The SEB Disturbance - The SEB usually consists of two components, the nSEB and sSEB. They are usually separated by the SEB zone, SEBZ, which may not always be visible. The nSEB is usually the wider and darker of the two. The fading of the southern component (ie. of the sSEB) is usually followed by the dramatic increase in activity in the SEB. This is the SEB Disturbance. A clear SEBZ and faded sSEB usually precede the appearance of a white oval within the SEBZ, the first sign that an SEB disturbance has begun. Within days, dark material is ejected from within the spot and is sheared by the winds in the SEBZ. Soon, other white spots form in the SEBZ and within a few weeks of the original eruption, the SEB region is filled with a foamy string of ovals and a multitude of dark spots.

The long-enduring white ovals BC, DE and FA - The ovals BC, DE and FA were initially observed around 1939-40 by Elmer Reese. They initially appeared as three long dark segments called AB, CD, and EF, with white cloud between them, up to 90 degrees in longitudinal extent. These dark segments increased in length (ie. in longitude) such that the white sections decreased into ovals which took on the letters of the ends of the dark segments. Hence they were called FA, BC and DE. During the late 1990's/early 2000s, the three ovals merged, gradually, to form oval BA which is still visible in the STB. As of mid-March 2005, it resides at the boundary between a normal-appearing dark STB, and a section of STB undergoing an STB-fade.

The Great Red Spot - The GRS is a large, usually red or salmon pink coloured high-pressure system located at the border of the SEB and the STrZ. Being a high-pressue system in the southern hemisphere, it rotates counterclockwise, and does this in about 6 days. In resides in a cavity in the SEB called the GRS Hollow, a region of STrZ which 'intrudes' into the SEB. The longitudinal extent of the GRS can vary slightly from year to year, but is usually around 18o long. There is a great deal of evidence to show that it is shrinking and may, in many years to come, either shrink into invisibility, or collapse once it has reached a certain size.

Due to its colour, it is easily visible in most apparitions, however a blue filter, such as a Wratten 80A, 82, or 38A can help darken the GRS and make it more easily visible against the surrounding cloud deck.

An interesting phenomena which occurs near the GRS is the interaction of ovals, along the SEBs, with the GRS. The SEBs retrogrades (moves westward) and so any ovals lying along the southern edge of the SEB will eventually "collide" with the GRS. This collision can occur over several days or weeks. As the oval collides with the GRS, it is swept around the GRS, usually in the GRS hollow. When the collision ends, the oval may be destroyed due to shear forces, become integrated into the GRS, or may exit the collision intact. This collage shows the approach of an oval on the SEBs with the GRS during February 2005. You can see that although oval A remains stationary with respect to the GRS, oval B retrogrades towards the GRS and, by February 26, has begun its collision with the GRS. I didn't get a chance to determine what the outcome of the even was.

 Blue Festoons - Most of the morphology of Jupiter's clouds is symmetrical about the axis of rotation and appears as belts or zones. However the equatorial region of Jupiter displays a striking exception to this system. Lying a few degrees north of the equator are a chain of large bright clouds known as the Equatorial Plumes. Each Plume has a roughly triangular shape, with the long edge located at approximately 9oN latitude, almost along the south edge of the NEB, and the hypotenuse sloping to the southwest. The blunt end of one Plume precedes the apex of the following one, and the space between them is a bluish-grey "interplume" region. The interplume regions are commonly called Festoons by amateur astronomers. As the name implies, the Plumes appear to be caused by rapid upwelling resulting in cloud formation, and may similar to terrestrial cumulonimbus, averaging about 25,000 km long and about half as wide (1,2). The festoons, and the blue areas from which they appear to project from are bright 5 micron emission features and show enhanced methane absorption, suggesting they contain less cloud material than the plumes. It is likely that the festoons are regions of downwelling material which compensates for the upwelling cores. Each festoon seems to project from a feature called an NEB projection or "plateau". This base is usually very blue, more so than the festoon, and is the part of the Equatorial Zone most observers say they see 'blue spots' in. This simple diagram shows the morphology of the region as viewed from Earth. An X marks the equatorial projection from which arises each festoon. The blue is thought to be due to the absence of cloud material. The region, being full of gas, disperses blue light more than red in the same way that the Earths atmosphere disperses blue light causing it to appear blue. In these blue regions, we can "see" further down into the atmosphere of Jupiter. This dispersion of blue light causes the feature to appear blue, and not because of the presence of blue chemicals.

The Equatorial Zone, into which the blue projections and festoons reside, is undergoing constant and rapid change so that drawing this region, or keeping track of any particular feature is difficult. The blue projections can persist for many months, but the festoons change shape within a period of days.


Filters

Filters for Visual Observing
Using filters can be both useful and difficult. It is best to use Kodak Wratten filters since their passbands are well characterized (unfortunately, amateurs simply never got used to the better Schott filters), and when using these, always quote the number which defines the filter type. Red features on Jupiter are made darker, and therefore easier to see, with a blue filter, such as a Wratten 80A, 82A or 38A. The 38A filter is dense and should be used on larger telescopes. The 80A and 82A allow more light to pass through so can be used on smaller telescopes. Blue features are made darker with red filters such as a W23 or W25 or an orange filters like W12 or W21. The 23A is better for smaller telescopes, while the 25A, being denser, is better for larger telescopes since it allows less light to pass through. Belts have an overall brownish-reddish colour and so are enhanced by blue filters. The 80A provides a subtle, but useful increase in contrast between belts and zones. Festoons, garlands and many features in the polar regions are bluish and so are made easier to see with a red filter. The 23A is most useful.

Filters for Imaging
Longer wavelengths, including red and near-infrared light, are less subject to atmospheric scattering. This leads to an improvement in the sharpness of images which can be obtained if red and near-infrared pass filters are used while imaging. However many features are reddish, and this means their visibility in such images is reduced while bluish features are easily visible. Strong methane absorption filters (which transmit 889 nm light) can be used to determine the relative heights of cloud features on Jupiter. Such filters are frequenctly expensive, especially if their FWHM values are low (i.e. they are selective for the strong methane absorption band at 889 nm). They also require long exposures.

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Transit Timings

I wrote an article on how to make transit timings.

Jupiter does not rotate on its axis as a solid body with a uniform rate of rotation like the Earth. Each latitude on Jupiter has its own period of rotation, and sometimes, individual features on the same latitude can rotate at different rates, sometimes leading to collisions. The equatorial zone, extending from the south edge of the NEB (NEBs) to the north edge of the SEB (nSEB) is referred to as System I (SI) and has a rotation period of 9h 50m 30s. The rest of the planet is called System II (SII) and rotates with a period of 9h 55m 40s, somewhat slower than the equatorial (or System I) region.

The central meridian is an imaginary line going from pole to pole on the disk of the planet. When a cloud feature passes the CM, an observer can note down the the Universal Time and Date. There are then two ways in which a person can determine the longitude of a Jovian cloud feature using these transit timings. It is possible to use a computer program, such as Tracker 6, which lets you input the Universal Time and Date. The program then computes the SI and SII longitude present at the CM and thus of the cloud feature. Alternatively, it is possible to use tables in publications such as the Astronomical Almanac to convert the Universal Time and Date to the longitude at the CM, and thus of the cloud feature observed.

An excellent program called PC-JUPOS can be used to maintain transit timing observations in a computer database, and to display them on graphs. It can be obtained at the JUPOS - Database for Object Positions on Jupiter website

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Drawing

Eventually, most planetary observers will try to draw Jupiter. However it is far more valuable to obtain transit timings of features as they cross the central meridian, the imaginary line going from pole to pole. A dozen or so good drawings per apparition are usually enough to record the appearance of Jupiter. However any dramatic changes occuring should be recorded in detail, and in this case, strip sketches are more adequate. Strip sketches are simply sketches of specific regions of the planet, such as the SEB, drawn in detail. These are good because the observer can concentrate on observing and drawing a specific region rather than trying to take into account the entire disk. Drawing the entire disk can be quite daunting if the seeing is good enough to provide abundant visible detail. To prevent distortion of the drawing due to the rapid rotation of Jupiter, you have to complete the entire disk-drawing in about 5-10 minutes or less. This sounds easy but to do it accurately can be difficult.

Transit timings are not only easier, and can be obtained for many features during a 2-3 hour observing period, but if timings of the same features are obtained over many weeks and months, they can reveal changes in a features velocity - something which is not evident from drawings.

Here is an article I wrote on how to make transit timing estimates of Jupiters cloud features.

Drawings - 1997
Image data: 320mm Newtonian reflector, 4.8-mm Nagler, 80A Wratten filter. St Lucia, Queensland, Australia.

August 2, 1997
August 5, 1997
August 10, 1997
August 11, 1997
August 12, 1997
August 15, 1997
Sep 14, 1997
Strip drawing, Aug 10-15, 1997

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Last updated 31.3.2007