Vol. 26 No. 7 April 1997


THE APRIL MEETING

The April 1997 meeting of the Ogden Astronomical Society will be held on Thursday evening April 10. The location is the Layton P. Ott Planetarium on the Weber State University campus, Ogden, Utah. The time is 7:30 p.m..

Members and visitors this month are invited to enjoy the most recent Ott production "Voyage to The Planets." This planetarium program, produced at the Ott, features stunning images and animations of the planets and our solar system. The voyage will take you to the outer reaches of our system and will include remarkable simulated flybys over the surfaces of several planets.

The most recent star parties, and the events coming soon, will also be discussed. Numerous members have taken beautiful photographs of comet Hale-Bopp. All those who have done so are encouraged to bring your photos to show to everyone.

STAR PARTIES IN APRIL

Two major public events are set for the early part of April.

BARNES and NOBLE

The star party originally scheduled for Friday, March 28 at the Barnes and Noble book store in Bountiful had to be replanned due to our unpredictable weather. The management has requested that Friday, April, 4 be set for another attempt for patrons and visitors to view the comet. Members are asked to try again by assembling telescopes near the west side of the store around 7:00 p.m. If the weather looks rough, check with Bob, he will coordinate with management.

ANTELOPE ISLAND

The first in this year's series of public star parties at the Island is set for Saturday, April 5. O.A.S. members can assemble their equipment anytime that day. If the weather is kind, mid day solar viewing is expected to entertain visitors before the stars come out.

Members are to introduce themselves at the island gate and there will be no admission fee. Club caps and shirts are always a help.



LOTS OF PEOPLE BUT MEDIOCRE SKIES AT WEBER COUNTY FAIR GROUNDS

Even with the failing weather conditions for Friday night's star party at the Barnes and Noble store, hopes held firm for a successful event at the Weber County Fair grounds on Saturday, March 29. At least 14 members showed up with telescopes and binoculars to show the comet, Mars and the other sky objects to an estimated 250 visitors.

Too bad the sky-luck let us down again though. A layer of very high thin clouds or haze came over the entire valley and by 8:30 p.m. the only objects visible were the very brightest stars and the planet Mars.

The event is considered highly successful anyway since most guests came early enough to see Hale-Bopp before it got too low to the horizon. The other sky viewing was an extra treat to those just expecting to see the comet.

The usual oooh's and aaah's were common all night especially from the crowd around B.O.B. Doug Say has completed another upgrade of the club's 18.5 inch by removing about 35 pounds from the structure, making it move much smoother and adding the Sky Wizard. The telescope should be at all subsequent club star parties. If you haven't had the opportunity to check out the improved club toy, come and look.

MINUTES

OGDEN ASTRONOMICAL SOCIETY

March 13, 1997

President Steve Peterson opened with welcomes at 7:30 p.m.

Forthcoming star parties were discussed. Dr. Sohl can use help on Wednesday nights after the planetarium shows. Just show up.

Elgie's observatory was discussed and Elgie was presented with a sign for his door, "Elgie's Play House".

Dave Miller introduced Gae Leashman from Morris Travel to discuss the Solar Eclipse tour next February.

Cliff Peterson exhibited and demonstrated his Dobsonian mounted binoculars. Perfect for viewing the comet.

Doug Say was introduced to set up and show off the recently remodeled club telescope.

John Sohl invited members to participate in a star party at City of Rocks National Reserve in southern Idaho. People interested can call Emily Fergison at (208) 824-5519 or call Dr. Sohl.

Adjourned at 9:10 p.m.

Click here for an article on telescope design and testing by member and professional telescope maker Bob Jones.

7 TO 7

Events of Interest Appearing in a Sky Near You

by Jim McCormick

Beginning this month and continuing for who knows how long, I will be making this monthly contribution to the Star Diagonal. My intention is to offer a number of astronomical "events" occurring in the period from the 7th of each month to the 7th of the following month---thereby the name of the column. These events will include lunar occultations of bright stars, comets, asteroids, novae and other objects demonstrating that the solar system, galaxy and universe are places, full of action and change.

These subjects will be gleaned from popular periodicals, the Internet, planetarium software and, hopefully, will be suggested by O.A.S. members. No doubt the column will evolve over the coming months with some features being dropped and others added. Reader suggestions and criticisms are encouraged (but be kind).

* * * * *

Let's begin with comets. Everyone is talking about and has seen Hale-Bopp unless they have been in a coma (no pun intended) for the last several weeks. H-B is apparently living up to expectations--a truly magnificent specimen. But there is another comet in the sky right now---and I am inclined to call it Comet Dangerfield as it had been getting no respect---periodic comet Wild 2. W 2 is very well placed for early evening observation and can be found in Cancer.

I noticed P/Wild2 listed as one of the "comets currently visible" on the JPL's comet page (http://encke.jpl.nasa.gov/). Observer reports indicated a magnitude of 9.6, but a comet with low surface brightness. On March 27 at 21:54 MST I found Wild2 near µ2 Cancri. The comet was a bit brighter than expected and appeared to be fan shaped. Wild2 was not easy to locate (with a 10' f/4.5 reflector at 42x) due to its location away from a naked eye star and I ran back and forth between the telescope and computer screen several times before its position could be pinned down. For those wishing to see the this run-of- the mill comet (in comparison to Hale-Bopp) look just a bit north of the Beehive Cluster (M44) on the evening of April 15 heading eastward at about one arc minute per hour. The comet will be about 50' from the cluster's center and 45' southwest of Cancri around 21:00 MDT.

* * * * *

When we observe stars through a telescope they appear fixed, rock-solid and permanent. Most of the time, except when a not so occasional satellite drifts across the field of view, a star field is placid. It is consequently quite startling when a star we are watching very suddenly disappears. This effect can be seen when the Moon passes in front of (occults) a bright star. The brighter the star, the more dramatic the effect. On the evening of April 7, at 22:46 MDT (if you are observing from the Ogden area) have your telescope and your gaze centered on Aldebaran ( Tauri) when the Moon's dark leading edge snuffs out it photons. Compare the Aldebaran occultation with that of (Lambda) Tauri, a 3.6 mag star, on April 13. This occultation occurs at 23:48 MDT.

* * * * *

Have you noticed Jupiter in the southeast sky before sunrise? Currently Earth lies near Jupiter's equatorial plane and we can witness osculations of its moons with one another. While running sky simulations for these events recently I wondered how often Jupiter can be seen without at least one of it four Galilean satellites tagging along. All four moons line up on the far side of Jupiter's equatorial plane, occultations of the outer moons Ganymede and Callisto will not always occur on these occasions making the phenomenon even more infrequent. Also keep in mind that a similar effect happens when one or more of the moons is transiting Jupiter. A combination of superior and inferior conjunctions make the appearance of a lonely Jupiter a bit more common.

I will be searching for such an event and report the next occurrence in a subsequent column. In the meantime, if any member with planetarium software can beat me to the punch, please contact me at 773-8069 or zubenelg@aol.com.

Elgie's Pictures of the Month

Two popular galaxies, Messier 81 (left) and Messier 82 (right) taken on March 26, 1997 with the

ST-5 for 5 minutes at minus 10 Celsius. Using the CCDSoft software, he used Track and Accumulate mode to obtain the best resolution he could achieve. These two galaxies are favorites to view in the early spring. M-8 is a beautiful spiral of mag. 7.9 and M-82 is a disrupted spiral of mag. 9.2.

"Have you ever had a night alone, just your and your telescope and the skies above? In early Spring the night is pleasant, the skies real clear and you are looking through your telescope at a galaxy while wondering if someone there is looking back. Well that is what I did on this March evening, looking at M-81, thinking how small I was compared the Heaven above me; taking CCD images, and here they are."

E. Mills