Prime Focus

The newsletter of the Tri-Valley Stargazers July 1997.
Translated (roughly) from postscript into HTML for your browsing and downloading pleasure.

Fireworks on the Fourth

Mars Pathfinder is due to land on the planet the morning of the Fourth of July (California time). The global shot and closeup locate Ares Vallis, the expected landing site for Pathfinder. This rocky plain is an ancient outflow chanel, chosen for its expected variety of geological samples. A six-wheeled rover named Sojourner will collect material that has been deposited from highland locations during episodic innundations. New Martian images will be captured by both the rover and lander. (Photo credit: NASA and NSSDC)


July general meeting
Club news notes
Star parties
What's Up in July
Comet Comments
Membership application

TVS presents

What: Summer barbeque and eyepiece test drive
When: July 18, 1997 Setup, 7:00 p.m. Dinner, 7:30 PM
Who: You and your family and Jack Marling, Ph.D.
Where: Unitarian Universalist Church in Livermore, 1893 N. Vasco Rd.

It's summer time, and the TVS summer barbeque is here again. Our general meeting for July will be a combination cookout and eyepiece demonstration by Jack Marling of Lumicon.

A patron member and long-time supporter of the club, Jack has agreed to bring a variety of wide field accessories for members to compare. He will supply a selection of economy Plossls, as well as investment-quality eyepieces that display a broad section of the sky. You may wish to bring your own scope so that you can try one of the new designs with your equipment.

TVS will provide the grilled edibles, soft drinks, coffee, paper plates, and cutlery. Members should bring a dish to share, according to the chart below.

A - Q side dish or salad
R - Z dessert

Family members and friends are invited to the barbeque and Jack's talk afterward. See you there!

Club news notes for July

Attention job hunters
The full-time position at Lumicon has not yet been filled. Those interested may send resumes to: Lumicon, Jack Marling, P.O. Box 495, Livermore, CA 94551. Please do not call in response to this opening.

Astronomer suffers theft
In mid-May, Gareth Thomson visited Sacramento with observing equipment in his car. Unfortunately, theives broke into the automobile and stole his gear. Please notify the Sacramento police department at (916) 264-5771, and reference police report number 97-39 263 if you are offered any of the following equipment: Thank you for keeping your eyes open for these missing items.

Membership update
Club treasurer Gene Nassar has conducted an audit of the membership. Our new total is 186, counting each family membership as only two.

Congratulations to Laurie Lane, who has just updated her status to Patron membership. Thanks, Laurie. At the barbeque, be sure to welcome the following new TVS members: Patrick Knapp, Thomas Kataga, Leo C. P. Leung, Leonard DiPinto, Derek Shelton, Richard and Roxanne Wolfe, and Charles James.

FPOA/AANC Star-B-Que planned
Fremont Peak Observatory Association and the Astronomical Association of Northern California invite all astronomers to their potluck picnic and star party at Fremont Peak State Park, Saturday August 2.

State Park entry fee is $3 per car, unless you are reserving a numbered campsite. Call the FPOA hotline at (408) 623-2465 by July 30, with your name and number of guests.

President Dave Anderson (510) 661-4249
Secretary Bill Burnap (510 ) 449-4552
Vice President Chuck Grant (510) 449-1500
Treasurer Gene Nassar (510) 462-7843
Observatory Director Chuck Grant (510) 449-1500
Librarian Chris Cody (707) 747-6550
Eyes on the Skies BBS Mike Rushford
Web Site
Editor Alane Alchorn (510) 455-9464 (510) 455-9466 fax
Meeting Location Unitarian Universalist Church in Livermore 1893 N. Vasco Rd. 3/4 mile north of I-580
Board Alane Alchorn Dennis Beckley Rich Combs Rich Green Russ Kirk Dave Rodrigues Debbie Scherrer Al Smith Dave Sworin Jim Zumstein
Membership: 186

Tri-Valley Stargazers

P.O. Box 2467
Livermore, CA 94551

Star parties

For information on these or any other star parties refer to the club website.

What's Up in July

by Dave Anderson

July 1997
1 Tue Io's shadow transits Jupiter 2:34 AM, followed by Io 3:27 AM PDT.
Io eclipsed by Jupiter's shadow 11:53 PM, reappears from occultation 3:03 AM
2 Wed Io's shadow transits Jupiter until 11:20 PM Io transits until 12:12 AM
3 Thu White Mountains Star Party. (Grandview campground tonight).
Planetfest'97 begins Pasadena. (Contact Cindy Jalife, The Planetary Society, 818-793-5100, for information.)
4 Fri White Mountains Star Party. (Barcroft High-Altitude Research Facility).
Independence Day.
New Moon 11:40 AM
Excellent weekend for observing.
Mars Pathfinder lands on Mars.
Earth at aphelion (farthest from Sun: 1.017 AU = 152,104,000 km).
Comet 2P/Encke 0.1901 AU from Earth.
5 Sat Star party at Sycamore Grove Park (Livermore Park District) 8:30 PM (Wetmore Rd. entrance near Holmes St.).
White Mountains Star Party.
6 Sun White Mountains Star Party.
Venus 5° north of Moon.
7 Mon Europa eclipsed by Jupiter's shadow 1:30 AM
8 Tue Europa's shadow transits Jupiter until 11:24 PM
Europa transits until 12:52 AM
Io eclipsed by Jupiter's shadow 1:46 AM
11 Fri Mars 1.8° south of Moon.
Ganymede's shadow transits Jupiter 11:39 PM to 3:17 AM
Ganymede transit begins 2:25 AM
12 Sat First Quarter Moon 2:44 PM
15 Tue Europa's shadow transits Jupiter 11:07 PM to 1:59 AM
Europa transits 12:1 8 to 3:08 AM
17 Thu Space Shuttle Discovery (STS-85) launch scheduled. (Study of Earth's atmosphere, SEDSAT tethered satellite, extreme ultraviolet astronomy.)
Io's shadow transits Jupiter 12:05 AM
Io transits 1:25 AM
Io eclipsed 10:09 PM,
reappears from occult ation 12:59 AM
18 Fri Tri-Valley Stargazers meeting 7:30 PM Unitarian Universalist Church of Livermore, 1893 N. Vasco Road, Livermore. (3/4 mile north of I-580).
19 Sat Asteroid 2 Pallas (mag. 9.6) at opposition.
Full Moon 8:20 PM
20 Sun Neptune at opposition (mag 7.8, apparent diameter 2.3")..
21 Mon TVS Planning Meeting 7:00 PM Round Table Pizza, 1540 First St., Livermore
(in Orchard Supply/Longs/Safeway shopping center).
Jupiter 4° south of Moon. (Uranus and Neptune nearby.)
22 Tue Venus 1.2° north of Regulus. Look shortly after sunset (8:25 PM).
Ganymede occulted by Jupiter until 10:59 PM
Europa's shadow transits 1:41 AM;
Europa transits 2 :33 AM
23 Wed Yezdezred (Persian Zoroastrian) New Year 1287.
24 Thu Europa occulted by Jupiter until 11:44 PM
25 Fri Saturn 0.02° north of Moon (occulted in Hawaii).
Io's shadow transits Jupiter 9:14 to 11:32 PM
Io transits 9:35 to 11:54 PM
26 Sat Star party at Del Valle.
Last Quarter Moon 11:28 AM
Mercury 4.5° from Venus and 0.5° south of Regulus.
Delta Cephei at maximum 11:59 PM Variable rises to mag. 3.5 from 4.4 in about 1.5 days. (Period is 5.366 341 days). Compare Zeta Cephei (mag. 3.35) and Epsilon Cephei (mag. 4.2).
28 Mon Zoroastrian New Year 2387.
29 Tue Uranus at opposition (mag 5.7, apparent diameter 3.7").
Grazing ooccultation of Aldebaran by Moon south of Bay Area.
Ganymede eclipsed by Jupiter's shadow 9:34 PM, reappears from occultation 2:16 AM
30 Wed Europa eclipsed by Jupiter's shadow 10:40 PM, reappears from occultation 2:00 AM
Io eclipsed 1:57 AM, reappears from occultation 4:27 AM
August 1997
1 Fri Io's shadow transits Jupiter 11:08 PM to 1:27 AM
Io transits 11:19 PM to 1:38 AM PDT.
2 Sat Star party at Sycamore Grove Park (Livermore Park District) 8:30 PM (Wetmore Rd. entrance near Holmes St.).
Star-B-Que at Fremont Peak (South of Gilroy ) 5:00 PM
Mars 1.7° north of Spica.
3 Sun New Moon 1:14 AM
Excellent weekend for observing.
Mercury at greatest eastern elongation (27 ° ) in evening sky.
End of Mars Pathfinder's primary mission.
5 Tue Mercury 1.0° south of Moon (occulted in Greenland). Venus nearby.

Some Summertime Deep-Sky Objects

M5 One of the best globular clusters, in Serpens (Caput).
M13 The Great Hercules Cluster! Look for the mag. 12 galaxy NGC 6207 in the same field.
M92 Another fine globular cluster in Hercules, often overlooked.
M4 & M80 Two globular clusters near Antares in Scorpius.
M6 & M7 Two fine open clusters near the stinger of Scorpius.
M8, M20 & M17 The Lagoon, Trifid, and Swan Nebulae in Sagittarius!
M11 The Wild Duck Cluster in Scutum! Perhaps the richest of all galactic (open) clusters.
M57 The Ring Nebula, a famous planetary nebula in Lyra.
M27 The Dumbbell Nebula, a superb planetary in Vulpecula!
NGC6960/92/95 The Veil Nebula in Cygnus. A large supernova remnant. (Best with an OIII filter).
NGC7000 The North America Nebula. Fine in binoculars under dark skies.

Comet Comments

by Don Machholtz


C/1995 O1 (Hale-Bopp)
Date (00 UT) R.A. (2000) Dec El Sky Mag
07-01 06h41.3m -01° 37' 25° M 3.6
07-06 06h54.6m -03° 27' 26° M 3.8
07-11 06h54.6m -05° 16' 28° M 3.9
07-16 07h01.0m -07° 05' 30° M 4.1
07-21 07h07.1m -08° 55' 32° M 4.3
07-26 07h13.0m -10° 45' 35° M 4.4
07-31 07h18.8m -12° 36' 37° M 4.6
08-05 07h24.3m -14° 28' 39° M 4.7

Date (00 UT) R.A. (2000) Dec El Sky Mag
07-01 07h48.7 m -36° 06' 61° E 6.0
07-06 09h22.3 m -57° 51' 86° E 6.3
07-11 12h46.0 m -67° 39' 107 ° E 6.9
07-16 15h18.5 m -61° 58' 120 ° E 7.7
07-21 16h20.2 m -54° 40' 126 ° E 8.5
07-26 16h50.5 m -49° 07' 129° E 9.2
07-31 17h09.0 m -45° 02' 129 ° E 9.8
08-05 17h22.2 m -41° 58' 127 ° E 10.4

Comet Hale-Bopp and Periodic Comet Encke are not far apart in early July in the southern sky. They remain visible mainly to those in the equatorial areas and south of the equator.

As observers turned their instruments to observe Comet C/1997 J1 (Mueller), they also picked up a new comet, unrelated, but slightly brighter. It is now known as Comet C/1997 J2 (Meunier-Dupouy). This large comet will be closest to the sun next March at 3.05 AU when it should reach magnitude 10.

Meanwhile, a solar-orbiting satellite named SOHO has picked up ten new faint comets over the past year. All were imaged only by the satellite as they zoomed in toward the sun. Most seem to be following the same orbit as the Kreutz Sungrazing comets, disappearing as they rounded the sun. They were magnitude 2 to 8, with most at mag. 7-8.

COMET HUNTING NOTES: Of the 97 visual comet discovery events since 1/1/75, during which 73 comets were found and named, only four times was the comet found by accident. In early July 1975 Doug Berger and the late Dennis Milon found a comet while observing M 2. It had been found the previous day by a comet hunter (Toru Kobayashi of Japan). Then, twenty years later Alan Hale and Thomas Bopp chanced upon a new comet near M 70.

Orbital Elements

Object: Hale-Bopp P/Encke
Peri. Date: 1997 04 01.13800 1997 05 23.59776
Peri. Dist (AU): 0.9141405 AU 0.3313951 AU
Arg/Peri (2000): 130.58915 deg. 186.27201 deg.
Asc. Node (2000): 282.47069 deg. 334.72147 deg
Incl (2000): 089.42943 deg. 011.92956 deg
Eccen: 0.9951172 0.8500135
Orbital Period: ~2500 years 3.28 years
Ref: MPC 29568 MPC 29882
Epoch: 1997 06 01 1997 06 01
Absol. Mag/"n": -1.0/4.0 9.8/4.0

Tri-Valley Stargazers Membership/Renewal Application

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