BACKGROUND:
A long time in coming, I was finally able to get everything "together" with detailed Jupiter observation for two consequetive nights. This (long) detailed report covers Jovian System 2 longitude 300 up through 180, a total of 240 degrees, or 2/3 of the planet, with most of the detail from 50 to 180, representing the second night. (The first night I viewed the preceding area to the GRS, the second night the following) I have done a detailed drawing of that second night, the morning of 7/27/97, with 116 degrees Sys2 longitude on the Meridian, 202 degrees System 1. I will post my original preliminary drawing on my web page www.weatherman.com so you can refer to it, and re-draw it more accurately in weeks to come.
THANKS:
Special thanks to those on sci.astro.amateur, the Internet newsgroup, for helping me along to get to this point. I appreciate all the suggestions, transit timings, etc. Also, thanks to John Hall of Pegasus optics, and Rick Singmaster of Starmaster telescopes for putting together such a great scope.
OBSERVATION TIMES:
Observations were made on the morning of 7/26/97, for a good 90 minutes centered at 0645 GMT, and on 7/27/97, for a good two hours centered on 0545 GMT. Mainly used a 16" f/4.59 Starmaster with Pegasus optics, frequently stopped down to 160mm with an off-axis mask. Two 30mm Ultimas and a Televue binoviewer, provided mainly 233x viewing. I also viewed through other scopes, and will mention the differences.
BACKGROUND (again):
I will post my preliminary drawing on www.weatherman.com later this week (week of 7/28/97). I have just reached the proper blend of optical performance, and "seeing conditions" and experience this year to be able to attempt this. I know others here have much more experience than me, I tend to make a lot of "noise" about my astronomical achievements (ie.. central star in the Ring last month), thanks for bearing with me. I have logged about 100 hours behind the eyepiece viewing planets in the past few years, 90 % of that on Jupiter.
SUMMARY:
First a summary: There are many features on Jupiter of interest right now, but a few notable longitudes to be highlighted first. Then the full report. Note that System 1 longitudes refer to equatorial areas (and adjoining South Equatorial, and North Equatorial belts) System 2 longitudes are in the temperate areas. There is also System 3, in the polar areas, but they are rarely referred to. Many notable features follow System 2 such as the Great Red Spot. I derived the longitudes from the US Naval Observatory Handbook: Astronomical Almanac, 1997. My estimated longitudes are +/- 3 degrees, not as accurate as others. I noted up to 2 dozen or more white ovals at one point on the morning of 7/27.
GREAT RED SPOT: Was near approximately 60 degrees longitude (SYS 2)
I counted SIX white ovals currently interacting with the Great Red Spot in the Southern Temperate Belt... three large, and three small.
52 to 110 degrees (Sys 2)
Dark Red Ovals: (all on the northern fringe of the Northern Equatorial Belt)
Small Oval.. 125 deg. Sys 2
Large Oval.. 157 deg. Sys 2
Double Oval.. Previously reported at 270, and 288 (Sys 2) Longitude by others
Small Oval.. 355 deg. Sys 2
Large Oval.. 39 deg. Sys 2
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Brief summary of Jupiter views through 3 scopes: (full report in the 16" further below)
Through an 80mm refractor, with excellent optics, The Great Red Spot is marginally visible, the SEB, and NEB area easily detected, along with the NTB (northern Temperature belt). Io's shadow was easily detected, Io itself showed itself as a light grey near the Meridian while in transit, but barely detectable, but near the limb, it did appear as a white dot, again not very well defined.
In an 8" SCT with excellent optics, most features referred to below, in the 16", were visible, but with somewhat reduced contrast, making detection of the weakest features impossible. Still, most of the white ovals, and dark red ovals were seen along with the NEB, SEB, STB, NTB, NNTB, etc.
Finally, the report below was using a 16" dob-newt, frequently stopped down to 160mm, but using full aperture at times of best seeing in the two nights, allowing for better observing of features with weakest contrast.
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Transit of Io..7/26/97
I picked this up through mainly the 16" scope on the 26th of July, 1997 at 5:54 GMT through it's exit at 6:54. Itwas just following the shadow of Io, a dark black spot, very close since we are near opposition. The moon itself appeared as a small light grey dot when I picked it up just past the Meridian, but disappeared for about 20 minutes before reappearing as an increasingly bright white dot as it approached the Jovian limb (preceding limb). Very easily viewed towards the limb, even in smaller scopes.
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MAIN REPORT:
From South to North (inverted.. everything is upside down)
South Polar Region: Darker than the North Polar Region, and mostly featureless.
South South Temperate Belt: Visible on my first night of observing, the AM hours of 7/26/97, from 300 to 60 degrees Sys. 2 longitude, but not beyond 60 degrees on my second night of observing. Straight and narrow. Appearing to be superimposed on the South Polar Region, rather than the entry point to it.
South Temperate Belt: Fairly straight, and the lead-in point to the darker area of the South Polar Region. (or at least it gave that appearance) Many white ovals were detected just to the south, and just to the north of the belt, allowing one white oval to be completely adjacent with the Great Red Spot. Six white ovals in all, ranging from approx. 52 deg. Sys 2 longitude, to 110 deg. Sys 2 longitude, with three small ones just south of the STB, and the 3 larger ones just north of the STB, in the South equatorial zone. The preceding large white oval (first one from left to right, in this inverted view) was touching the STB, but also touching the GRS to the north. No disruption of the GRS or loss of color was observed (a concern of Don Parker). The white oval involved was about 10-15% of the size of the GRS.
South Equatorial Zone: Very narrow lighter region hetween the South Temperate Belt, and the South Equatorial Belt. Included 3 of the six white ovals as described above.
Great Red Spot: At larger aperture it appeared to be an salmon-orange color, just salmon at 160mm. It punches about 1/2 way into the Southern Equatorial Zone. It was large, and oval shaped, with a darker section in the south-center portion. Around 60 degrees Sys. 2 longitude.
Southern Equatorial Belt: Very complex! On my first night of observing, preceding the GRS, the SEB was fairly mundane through 65 degrees or so with some hints at a lighter portion, or some very very small white ovals along the belt, towards the north side. It is grayish in color. Then beginning around the Great Red Spot, (best observed on the 2nd night) and following almost the entire face of the planet, is a series of strung-together small white ovals that extend all the way from just following the Great Red Spot, on the north side, (lower right, not quite touching) at about 68 degrees System 2, 150 degrees System 1 longitude all the way through through 145 degrees System 2 longitude, 230 degrees System 1 longitude. There were about 9 small white ovals in all, but difficult to count. They extended up and to the right (towards the following limb, going from the north side of the belt, towards the south) at an angle, so that the ones near the Great Red Spot were near the northern part of the SEB, while the ones following ended up on the southern part of the SEB. They were somewhat strung together, and adjacent in places. Just one was slightly out of place with that line, about the 3rd oval from left to right. There was no mention of these being of concern in terms of interaction with the GRS on the A.L.P.O. page.
The Equatorial Zone: Great Stuff.. an occasionally broken thin Equatorial band was evident at almost all longitudes. Darker in some areas than others. Noticeably darker north of the Great Red Spot, but a difficult feature at times of poorer seeing. (also this will be tough in smaller or less optically perfect scopes). On the first night of observing, fairly prominent blue festoons were noted in the vicinity of the dark red ovals in the Northern Equatorial Belt. (see below). They pointed towards the following side of planet at about a 45 degree angle, just about to the equator.
The following in the Equatorial Zone was noted on the 2nd night of observing only, on 7/27/97, with my drawing was centered at 202 deg. System 1 longitude, 116 degrees System 2 longitude at 0511 GMT:
There was a darker round spot, in that equatorial band, but low contrast and very small located at 243 degrees System 1 longitude (157 Sys 2) which was towards the following side of the planet. Back to the preceding (left) side.. There was a blue festoon pointing at a 45 degree angle from the NEB into the EZ, just following the GRS at approximately 165 Sys 1 long. (85 Sys2). It did not quite reach the band. .Another weak blue festoon rose up and to the left for a change, from the NEB towards the preceding side, the opposite direction than normally observed. This just about reached the band on the equator. This eminated from the same vicinity, longitude wise, as a major white oval in the NEB which I will mention later. There was a curved bridge joining the Southern Equatorial Belt, and Northern Equatorial Belt at 228 degrees System 1 longitude, (142 Sys 2) or in other words, currently about two hours past (following) the Great Red Spot. (but it's placement will relatively "shift" compared to the GRS being a system 1 feature, as the GRS is system 2 which runs a bit slower). This bridge was interesting, as it ended up just following the aforementioned 2nd weak blue festoon, and in fact, joined it where it touched the south side of the Northern Equatorial Belt. Following these features was a low contrast white oval in the equatorial zone, just south of the Northern Equatorial Belt, at around 243 degrees System 1, (157 sys2).
Northern Equatorial Belt: Extremely active. A warm, almost orange or peach tone, similar to the Great Red Spot. On the first night, got to view two dark red ovals (very dark, hard to discern red) one on the preceding side at 355 degrees System 2, 73 degrees System 1. This was located on the northern fringe of the NEB, followed by a white oval, and a festoon extending up from the NEB into the Equatorial zone pointing towards the following side at a 45 degree angle. (as mentioned before) It was weaker than a few days ago, but the festoon still fairly prominent. Nearing the meridian was a slightly larger dark red oval at 39 degrees System 2, (118 Sys 1), also with an associated festoon pointing up into the EZ at a 45 degree angle. Festoons were light blue.
A much more detailed view was made the second night, in the NEB, further along in longitude.... Again, with a Meridian transit at 0511 GMT 7/27:
Starting at the preceding side.. Just beyond an aforementioned festoon, a white oval and very small dark oval on the SOUTHERN edge of the NEB followed. This was the only dark oval on the the south edge.. the rest were on the north edge. But more notably, the NEB then jogged on it's northern fringe towards the north just a bit, meeting a small dark red oval which was located at 125 degrees System 2, (210 System 1). This transited at 0527GMT. It was, like most of them, on the extreme NORTHERN edge of the NEB, and it was close to the meridian. Then what appeared to be a cut-out in the NEB's north side, was actually a large white oval punching in on the northern side, very prominent. It was just following the small dark red oval, just mentioned, and transited at 5:44 GMT, putting it at 135 degrees System 2, (222 Sys1). In my drawing, we are now past the meridian. Just above this, on the south side of the NEB was a blue festoon, low contrast, which I mentioned earlier. Also just following this position - was that bridge which came up (up, in this inverted view) out of the NEB. It was curved to the left, but ran a bit to the right, extending all the way to the SEB, pointing towards the following side of the planet. At this point, just following the large white oval...the NEB's north side then jogged decidedly northward culminating in one of those larger dark red ovals that we have been reporting for weeks. It follows the GRS, as guessed, by 2 hrs. and 40 minutes, if you want to view it. It was bordered by a low contrast white oval just underneath it in the Northern Temperate Zone. It was located at about System 2 157 degrees, (243 sys1) with an approximate transit time of 0620GMT. (I went to bed, so I could be off 5 minutes).
The Northern Equatorial Zone was sliced up by the Northern Temperate belts, which were very interesting as they shifted notably at the meridian on night 2. Night 1 was not particularly interesting with the NTB being more pronounced than the NNTB, and the NNTB leading to the North Polar Region.
The Northern Temperate Belts on night 2 however, started out on the preceding side straight enough, but towards the meridian took a jog at an angle of about 45 degrees or so northward suddenly almost joining the weaker NNTB. (Northern northern temperate belt). In actuality, this was a bridge to the NNTB of some sort, as the NTB continued on, but in a weaker fashion. Just as quickly as this bridge-like feature cut down, another bridge cut back up, from the NNTB and through the NTB, and finally connecting to the aforementioned small dark oval in the NEB!This bridge was located at about 120 degrees System 2. It's hard to explain, but just picture a "V"-like shape going from the NTB down to the NNTB, then back up to the NEB. At this point the NTB disappeared for a bit, while the NNTB became very dark and prominent with four weak white ovals just beneath it further north. Then towards the following limb, it almost disappeared, and the NTB became dark and promient again, taking over the ballgame! Finally, three more very low contrast white ovals were just beneath the NNTB on the following limb, even smaller and weaker than those just mentioned. All these ovals were essentially inside the North Polar Region.
NPR.. Not as dark as the SPR, fairly uniform, white ovals as described above.
END