NO O.A.S. MEETING AT THE OTT THIS MONTH
There will be no regular meeting of the Ogden Astronomical
Society held at Weber State this month. It was decided by the executive
committee that the Monte Cristo event would serve in its stead. The September
"Annual Meeting" will be held on September 11, 1997. Watch for
further information in next month's Star Diagonal.
ANTELOPE ISLAND IS SCHEDULED FOR AUGUST 9 AT THE 'BAY
The next public star party at Antelope Island is scheduled for this Saturday August 9, 1997. If the past couple of events are any example, this too should be a lot of fun for O.A.S. members and the public.
This late in the season, bugs are not a factor. Members are invited to come early and set up to observe the sun or test your skills on day time observing of planets and stars, (talk to Jim McCormick for details).
Tell the state ranger at the gate you are an O.A.S. member and the entrance
fee is waived. As in the past, the park entrance closes at 10:00 p.m. By
you can leave anytime via the automatic gate. Follow the yellow signs to
White Rock Bay. Call Steve, Elgie or Bob for further details.
HARMON'S SUPER STORE TO HOST ONE MORE STAR PARTY
This year's forth and final Harmon's public star party is scheduled for Saturday August 16, 1997. Members can set up their equipment and show off your astronomical skills for the public in the parking lot of the Roy Harmon's store before dusk on that evening.
The last Harmon's event in Ogden was a surprising success. A unique crowd of interested people made for a successful star party. In spite of the obviously limited seeing, the moon and a couple of bright planets gave way to the oooh's and aaah's that make these events so worth while.
Join the members in Roy on the 16th for this year's final up-town event.
NOMINATING COMMITTEE SEEKING O.A.S. MEMBERS WITH A VISION
Club President, Steve Peterson, has contacted and selected the three O.A.S. members to serve on this year's Nominating Committee for the F.Y. 1997-98 club officers. The September issue of the Star Diagonal will carry the names of members nominated, by the committee, for the four positions. Elections will take place at the September 11 meeting.
The committee is anxious to hear from O.A.S. members who are willing
to take the time to hold and administer a position in the club. Volunteer
your time and your ideas by contacting them before they contact you. New
ideas for club events and activities are needed and are always welcome.
This is the way you, the O.A.S. member, can have the needed influence on
the future of our association. For the committee members names, call Steve
Peterson at 393-6227.
EXEC. COMMITTEE DEPARTS
For the past twelve months your Executive Committee has attempted to
produce interesting meetings and enjoyable public and private events for
the club members. It is our sincere hope that we have been successful.
We are looking forward to newer and better things. Get involved.
Steve Peterson - President
Elgie Mills - Vice President
Bob Tillotson - Secretary/Star Diagonal Editor
Doug Say - Treasurer
MARS PATHFINDER VIDEOS
Dr. John Sohl has a few video tape sets left of the first two weeks of news conferences and first steps of the Sojourner rover from the Mars Pathfinder mission.
These consist of two video tapes and John is providing them to O.A.S.
members at cost; $8.00. Call John at 476-0588 (home) or 626-7907 (work).
Jupiter at Center Stage
On August 7th , Jupiter rises at 20:34 MDT and transits at 1:36.
By September 6th it rises at 18:26 and transits at 23:24. One
of the best times to observe the outer planets, Jupiter, Mars and Saturn
is during their transit of the meridian, not because they are closest to
Earth (they usually are not), but because their altitude is at a relative
maximum at this time. When these planets are near opposition, the situation
is even better. For Jupiter, opposition occurs on August 9th.
This year Jupiter will be about one degree below the ecliptic at opposition
so will not be at its best. The best oppositions for northern observers
occur during the winter months when the ecliptic is far above the horizon.
The GRS or Great Red Spot on Jupiter will be one "surface" feature
to look for this month. A better name, perhaps, would be the GPS or Great
Pink Spot so that those seeing it for the first time would not be disappointed.
I have picked the night of August 9th as an opportunity to view
the GRS, because other events will be coincident with the spot's arrival
at Jupiter's meridian. Incidentally, the GRS is not a fixed cloud feature
and drifts east and west slightly while maintaining the same latitude in
Jupiter's southern hemisphere. All predictions regarding the spot's location
will be based on the most currently published longitude (60). On August
9th, the GRS should transit Jupiter's central meridian at 23:10
MDT.
The other action that evening involve Jupiter's moons Europa and Io. Europa will begin to transit Jupiter at 21:06 MDT with its shadow following one minute later. While Europa is still moving from east to west across the face of Jove, Io will be approaching the western edge to the giant planet and will be occulted by Jupiter at 23:18. Due to Jupiter's atmosphere, this occultation will progress more slowly than a stellar occultation by the Moon. A little more than a half hour later, at 23:57, Europa's transit will end with its shadow disappearing two minutes later. Figure 1 shows the positions of the GRS, Europa and its shadow and Io around 23:10. The view through your telescope will differ depending on its type. For a refractor without a star diagonal, simply turn this page upside down.
For a different kind of event involving Jupiter and one of its moons,
observe Callisto as it emerges from Jupiter's shadow on August 10th
. The entire event lasts 11 minutes from 21:35 to 21:46. This event will
occur very close to Jupiter's east (celestial) side, just above the Jovian
equator. When it has completely returned to sunlight, Callisto will shine
at magnitude 5.3. While this return of Callisto is progressing, look also
for Io and its shadow nearly dead-center on Jupiter.
Mercury Joins Venus, Mars Hangs In There
We have been observing Venus (a horizon hugger this apparition) as an evening "star" for the past couple of months. She is joined by Mercury in early August. Both planets will be well past quadrature on the evening of August 7th , swinging back to the west heading for inferior conjunction with the Sun. On the 7th , look for Mercury 7.22 southwest of Venus. Mercury will be 26.7 from the Sun, which sets at 20:31. Venus will appear as a gibbous disk 12.7" across while Mercury will be a thick crescent measuring just 8.7" from tip to tip. Figure 2 shows the phase and relative size of these inner neighbors.
Mars grows smaller but is now more massive with the addition of Sojourner
and Rover. On the 7th of August Mars can be found a bit less
than 3 east of Spica. Mars sets at 23:19 on the 7th and by 21:16
on September 6th, becoming increasingly more difficult to find
in the Sun's glare.
Lunar
activities
On August 11 at 22:52 MDT the Moon will occult magnitude 5.4 star (Eta)
Libra. The Moon will be slightly gibbous (8.89 days old) so will have plenty
of dark leading edge to produce an interesting effect as it snuffs out
Eta's light. Another occultation of Aldebaran will occur this month, but
this one will be a daytime event. Aldebaran is bright enough to be easily
seen in the daytime and the Moon will help you locate it. The occultation
occurs on the morning of August 25th at 11:17, so look for Aldebaran
a few minutes earlier when the 0.8 magnitude star is just off the Moon's
sunlit leading edge about 38 above the Lunar equator. When this occultation
occurs the Moon will be in the southwest sky about 40 above the horizon.
For those who enjoy searching for the "young" Moon, look almost
due west, ~ 4 above the horizon at 19:54 on the 2nd of September.
By no means in record territory, the 1.09 day-old crescent Moon will be
a naked-eye challenge, but an easy binocular find.
Uranus and Neptune
It's surprising to me that hardly anyone at star parties, including we OAS'ers make an attempt to find Uranus and Neptune. And I must admit this colorful duo are usually the last objects I seek. Is it because most think they are too difficult to find, too small or perhaps just don't compare to the other planets?
If so, all of these reasons are not well founded. They are in fact easy
to locate (especially true for Uranus). Lacking detail, they are not unlike
Venus or Mercury if you disregard the latter's phases. They certainly have
color. When I show this pair to star party visitors, I always ask them
what color they see for each. Invariably the unprejudiced answer is "blue".
After closer examination, they usually see that Uranus is green-blue while
Neptune remains definitely blue.
True, they present small disks....but they are definitely not stellar pinpoints
of light. They are both well worth the effort. Figure 3 above shows their
locations (Telrad superimposed) relative to Capricorn on the night of August
22nd. Next time out, give 'em a try.
Graphics were generated with GUIDE5 software and edited by the author.