MIRROR LAB SCHEDULED FOR THE JUNE MEETING

There is something very different scheduled for the June 12, 1997 meeting. The Ogden Astronomical Society will come to order in Weber State University's Science Lab building, next to the Ott Planetarium, at 6:30 p.m. That is one hour earlier than usual. The lab building is located right next door, south, of the planetarium. The Optics lab is in room SL 232 (second floor).

This is an invitation for members and friends to bring their telescopes and/or mirrors, for cleaning and columnating. O.A.S. member and master mirror maker Bob Jones will oversee the lab. Bob will bring some of his own test equipment so members can test their mirrors and make adjustments to their instruments.

Don't miss this rare opportunity to learn the correct methods to clean and tune your optics.

TWO STAR PARTIES ARE PLANNED IN JUNE

The June Antelope Island event is set for this coming Saturday, June 7. Though Hale-Bopp is gone, we will have a two-day crescent moon, Mars remains prominent high overhead and the dark conditions at the island make it easy to pick out the faint nebulae. For those interested, come early to observe the sun through solar filters and participate in a Tail Gate party. John Sohl will arrange for the usual media blitz so we are expecting another large crowd. Check out the article in this issue describing last month's Antelope Island star party.

On Saturday, June 14, the O.A.S. will host its first public star party in the parking lot of the Roy Harmon's Shopping Center. Bob T. has met with the store management and fliers, announcing this event, are being circulated. This should be a good one. Details for this star party will be available at the June 12 meeting.

CLUB SHIRTS AND CAPS ARE STILL AVAILABLE

We still have a reasonable selection of O.A.S. Tee Shirts, Sweat Shirts and Caps available. These are great for the public star parties to set the members apart from the crowd. Check with Doug Say for details and prices.

A LARGE AND ENTHUSIASTIC CROWD CAME TO GREEN ACRES ELEMENTARY SCHOOL

It was quite an evening on May 16, at Green Acres Elementary in North Ogden, with the number of kids, parents and teachers estimated in excess of 400. The people were itching to look through the telescopes even before the sky was dark. The moon and Mars turned out to be the best objects observable though since we were treated to mostly cloudy skies.

That didn't seem to detour the enthusiasm and the Ooohs and Aaahs were heard throughout the evening. The lines were long because only four telescopes showed up and the time it was taking to get to the eyepieces was taking a toll on the patience of some. However, almost everyone got a look. The school hosted cookies and soft drinks for everyone and the monetary donation to the club fund always helps to maintain B.O.B.

Many thanks go to those who participated.

By Jim McCormick

The opposition of Pluto occurred on May 26, so the opportunity to find the faint planet is still very good. Last month I pointed out a trapezoid of stars near 18 Sco. that helps in the location of Pluto. This asterism again comes to our aid on the night of June 12 when Pluto appears just 2' north of the northwest corner of the trapezoid, a star of magnitude 9.5 (GSC 5613 740). The circle to the right represents a 1 field showing the positions of 18 Sco. and Pluto's location relative to the "trapezoid".

We can begin to focus our attention on Jupiter, by June 7^th rising at 0:53 MDT, now high in the southeastern sky before dawn. John Rogers, a member of the British Astronomical Association reported May 13 that a white oval impinging on Jupiter's Great Red Spot is showing signs of "unprecedented" disturbance. Rogers is asking for images and observation of this event. The GRS will be near Jupiter's meridian at the following times (all in the wee hours of the morning): June 13, 2:30; June 15, 4:00; June 18, 1:30; June 20, 3:00 and June 22, 4:30. All times are Mountain Daylight Time. The Moon should not interfere with any of these observations.

As Earth is now near Jupiter's equatorial plane, a number of interesting "mutual events" involving its moons can now be seen. Many of the more interesting of these are featured on page 78 of the June issue of Sky & Telescope. I would like to call your attention particularly to the event of June 19, 1:55 MDT when Europa is eclipsed by Io. Although this will be a partial eclipse, Europa illumination will be reduced by 58%. Europa usually shines at magnitude 5.3. During this four minute eclipse, we should witness Europa's brightness dim quite noticeably. Incidentally, Europa will be the second moon west of Jupiter at the time of this event; Io will be found between Jupiter and Europa.

Mars will still be available, but the red planet is shrinking rapidly and will present a disk only 8.5" pole to pole. With a disk so small it will be difficult to see much detail. No major features such as Syrtis Major will be turned toward Earth that night, but observers with the right equipment might be able to see the pipe-shaped shadowy feature in Mars' southern hemisphere. The gas giants Jupiter, Uranus and Neptune can be observed by those willing to stay late. Neptune doesn't rise until 23:37. Both Uranus and Jupiter will up before 1:00 a.m. And for those really devoted planet seekers, Saturn breaks the horizon at 3:14 a.m. Although Mercury will be up before the Sun, it lies just 18 away and rises about an hour before the Sun. Mercury will be only nine degrees above the horizon when the Sun rises. Might as well forget this one.

The AI Party should be a feeding frenzy for B.O.B. (The Big Ogden Bucket) as the Virgo Galaxy Cluster will high in the sky in the bowl-shaped asterism representing the head and right arm of Virgo. Within 5 of Rho () Virginis [R.A. 12:41.9 Dec. N 10.2] can be found the following Messier Galaxies: M58 (10.5), M59 (10.5), M60 (8.8), M87 (9.5), M88 (10.2), M89 (10.5) and M90 (10.3). Further north in Coma Berenices, BOB will find the "Black eye" Galaxy, M64, an 8.6 magnitude spiral with a dark dust lane south of the nucleus. M64's coordinates are, R.A. 12:56.7 Dec. +21.7. To locate M64 without setting circles, first draw an imaginary line from Denebola (tail of Leo) to Arcturus. From a point half way between these two stars go north and slightly west about 4 to find M64's field. These are some of the brighter galaxies in this part of the sky. Many, many more lie in the grasp of BOB and smaller telescope. The difficulty is not finding galaxies here, but identifying them. Come to the Island Saturday, June 7^th and enjoy the feast.

Twilight????

When exactly does "twilight" begin? It all depends on which of three definitions we are talking about. Civil Twilight begins when the Sun is 6 below the horizon. For Nautical Twilight the distance is 12 and for Astronomical Twilight the Sun is 18below the horizon. Nautical Twilight is the least common term, but defines the time when the sky is dark enough for sailors to use the stars to determine their ship's longitude and latitude.

In the June issue of Sky & Telescope on page 29 there is an article about the comet Hale-Bopp. In this article, David G. Schleicher from the Lowell Observatory estimated that in late March Hale-Bopp was releasing 1000 metric tons of dust and 130 metric tons of water every second. "Yikes," I said (a scientific term), just how long can this comet possibly last if it is releasing such a prodigious amount of material every second.

I had read in a previous article that the estimated size of the nucleus was 25 miles in diameter so I began to calculate. To get a starting point I had to make some assumptions. If there was rock and dust it would be heavier than liquid water, also there was water which would be frozen so per cubic foot would be lighter than liquid water. I therefore used liquid water as a compromise for the weight. I assumed that it continuously lost material at a constant rate and that its orbit remained constant at this distance so that the loss would continue year after year. I lastly assumed that a year is 365 and 1/4 days long.

Using these assumptions, which are bogus to start with I determined that Hale-Bopp would last 957 years. In reality it only would loose material for only a few months during each approach to the Sun and remain dormant during the remaining portion of the orbital period, which is currently more than 2000 years.

I can breathe easier now knowing it should return many times in the future.

Below are my figures for anyone interested.

The weather Gods must have lost track of the events schedule for the O.A.S. on Saturday May 10, 1997. As it turned out, the skies were near perfect even for deep sky viewing of faint galaxies and other nebulae. The four day moon, which was one reason this weekend was picked, lent a delightful hand in entertaining the visitors. In addition to the ideal conditions, one of the largest assemblies of telescopes, since we have been going to Antelope, were drawn to White Rock Bay or the sights and the skies. Sixteen telescopes of various types, styles and sizes were there. Dr. Sohl had done his usual good job of arranging advertising for the event through the newspapers and radio. I even heard from someone that one of the local TV stations mentioned the Antelope event during the weather report the night before.

With the skies so good, the star party went on and on. Cliff and Ron decided to stay all night; of course having their new motor home and fifth wheel there, respectively, was a nice incentive too. Cliff finally has his LX200 back from Meade so he was sporting a big smile. Steve Dodds was testing out his new 10-inch binoculars and Bob Jones exhibited his newest 10-inch optical creation. Deloy and Karen Pierce had also made a deal on a new 'scope just that day and had brought it along.

It was a fine star party. The crowd was enthusiastic but orderly. There was no slide show this time which gave Dr. John a chance to enjoy the event a little more. We are looking toward another fine time in June.

Figure 1 is the last image I took with my ST-5 CCD. The image is of M104, the Sombrero Galaxy (NGC 4594) and is in the constellation Virgo. It was taken on the May 12, 1997 at 23:48 MDT. It is a 400 second exposure. The galaxy's overall magnitude is 8.3. Some of the stars in the image are magnitude 17+ I took a lot of images with this camera and enjoyed it a lot.

Figure 2 is one of the first image's I have taken with my new ST-6 CCD camera (I sold the ST-5) . It was cloudy the night I took this image of M27 and it has been cloudy nearly every night since I recived the ST-6. This image of the Dumbbell Nebula (NGC 6853) is a 300 second exposure taken on May 16, 1997 at 01:53 MDT. M27 is magnitude 8.1, in the constellation Vulpecula. This image is unprocessed and is out of focus a little due to clouds. It was taken at f/6.3 and had the CCD set at -30c. The new ST-6 CCD limiting Magnitude is 14.5 at 1 second with a 20cm Aperture and a magnitude of 18 at 1minute with a 20cm Aperture.