The modern plagues of light pollution and persistent industrial haze did not bedevil ancient astronomers. For them, the stars were eternal, predictable, and very visible. Familiar constellations, graced with compelling names we no longer recognize, wheeled seasonally in an orderly procession. Night after night. Year after year. Lifetime after lifetime.
Club member Alane Alchorn will discuss the ways in which constellations and asterisms have been recognized in different cultures.
by Rich Combs After much soul searching (a minute or two), I've decided it's time for another telescope making workshop. Tentative plans are to have an orientation meeting in mid-September, then I'll order the glass, and we will start grinding in late September or early October.
The goal will be for everyone to have a finished telescope by Christmas. We will meet twice a week on Monday and Wednesday evenings, with a few Saturday sessions to build the mounts. The object of the workshop is a complete working telescope of better-than-average quality. We will grind, polish and figure the mirrors, most likely 6" f/8 parabolas, and build Dobsoninan mounts for the Newtonian reflector optical assemblies. For each scope, the focuser, secondary mirror, eyepieces, and finders will be bought commercially.
The mirrors will be aluminized by a professional coater. Total cost will be around $300-350. If you are on a tight budget some corners can be cut. There is no registration fee for the class. We'll be meeting in Sunol from about 7-9 PM.
You're following in the footsteps of about 40 previous workshop graduates, and will benefit from what we have learned over the last five years.
The only prerequisite is perseverance. You will succeed, but it will take a commitment on your part. Successful mirrors have been made by 12 year olds, students, liquor store owners; why, I even had an astrophysicist make a successful telescope! If they can do it, so can you.
If you are interested, please e-mail me back, and I will send more details as they are available. Looking forward to hearing from you. My e-mail address is: combs4@llnl.gov. My telephone number at home is: (510) 846-1906.
If you have opinions about the Dark Sky Site, its potential for new and expanded uses, or concerns about the club scope, contact Chuck via e-mail. Alternatively, you may address a letter to him and send it to: Tri-Valley Stargazers, Attention: Chuck Grant, P.O. Box 2467, Livermore, CA 94551.
A volunteer is also sought to revitalize the club's binocular telescope project. At present, the scope is sitting disassembled. Previous experience with binocular assemblies is not required. Contact Chuck Grant if you would like to help with this project.
Five new members joined our ranks last month. Please welcome Victor Sickinger, a student member, and Christopher Bailey, Weston Clark, and David and Alice Hollingsworth.
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
http://www.hooked. net/~tvs/eyes/
Web Site
http://www.hooked.net/~tvs/
Editor Alane Alchorn (510) 455-9464
(510) 455-9466 fax circlewing@aol.com
Meeting Location
Unitarian Universalist Church in Livermore 1893 N.
Vasco Rd.
3/4 mile north of I-580
Membership: 191
Board Alane Alchorn, Dennis Beckley, Rich Combs, Rich Green, Russ Kirk, Dave Rodrigues, Debbie Scherrer, Al Smith, Dave Sworin, Jim Zumstein
September 6 Sycamore Grove Park Livermore 8:00 PM
September 20 Sky Shack Observatory and Dark Site Final open house for 1997. Meet at Mines and Tesla Roads at 6:00 PM
For information on these or any other star parties refer to the club website.
---- With the school year back in session, we expect to receive requests from teaches for star parties. Rich Green, school star party chair, has created an e-mail list of members to be notified with upcoming dates. If you wish to be added to his list, call him at (510) 449-2190 for his e-mail address.
Space permitting, school star party information will also be printed here each month.
| September 1997 | ||
| 1 | Mon | Labor Day. |
| New Moon 4:52 PM PDT. | ||
| Partial solar eclipse in Australia. | ||
| Io transits Jupiter 12:43 to 3:01 AM; shadow transits 1:17 to 3:35 AM | ||
| Europa occulted by Jupiter 9:19 PM, reappears from eclipse 1:25 AM | ||
| Io occulted 9:57 PM, reappears from eclipse 12:49 AM | ||
| 2 | Tue | Moon at farthest apogee of year (40 6,479 km). |
| Io transits Jupiter until 9:28 PM; shadow transits until 10:04 PM | ||
| 3 | Wed | Europa's shadow transits Jupiter until 8:01 PM |
| Ganymede reappears from eclipse 9:15 PM | ||
| 4 | Thu | Asteroid 1 Ceres (mag 7.7) at opposition. |
| Callisto's shadow transits Jupiter until 11:01 PM | ||
| 5 | Fri | Venus 3° south of Moon and 1.9° north of Spica. |
| 6 | Sat | Star party at Sycamore Grove Park (Livermore Park District) 8:00 PM (Wetmore Rd. entrance near Holmes St.). |
| Mars 5° south of Moon. | ||
| 7 | Sun | Delta Cephei at maximum 10:19 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). |
| 8 | Mon | Ganymede's shadow eclipses Europa (partial; 99% light drop) 3:56 to 4:12 AM |
| Europa occulted by Jupiter 11:38 PM | ||
| Io occulted 11:43 PM to 2:44 AM | ||
| 9 | Tue | First Quarter Moon 6:31 PM |
| Io transits Jupiter 8:56 to 11:14 PM; shadow transits 9:42 PM to 12:00 AM | ||
| 10 | Wed | Europa transits Jupiter until 9:05 PM; shadow transits 7:45 to 10:36 PM |
| Io reappears from eclipse 9:13 PM | ||
| Ganymede reappears 1:16 AM | ||
| 11 | Thu | Coptic New Year (171 5 in Egypt, 1991 in Ethiopia). |
| 12 | Fri | Mars Global Surveyor inserted into orbit around Mars. |
| Callisto occulted by Jupiter 8:38 PM to 1:25 AM | ||
| 13 | Sat | Jupiter 4° south of Moon. |
| 16 | Tue | Full Moon ("Harvest Moon") 11:50 AM |
| Total lunar eclipse visible from Eastern Hemisphere. | ||
| Also second closest perigee of year (356,966 km). Expect high tides. | ||
| Mercury at greatest western elongation (18 °). Best morning apparition of year for northern latitudes. | ||
| Io occulted by Jupiter 1:29 AM | ||
| Europa occulted 1:59 AM | ||
| Io transits Jupiter 10:43 PM to 1:01 AM; shadow transits 11:37 PM to 1:55 AM | ||
| 17 | Wed | Galileo flyby of Callisto (524 km). |
| Io occulted by Jupiter 7:56 PM, reappears from eclipse 11:08 PM | ||
| Europa transits 8:34 to 11:24 PM; shadow transits 10:21 PM to 1:11 AM | ||
| Ganymede occulted 9:57 PM to 1:35 AM, eclipsed 1 :38 AM | ||
| 18 | Thu | Saturn 0.8° south of Moon (occulted in Los Angeles). |
| Space Shuttle Atlantis (STS-86) launch scheduled. (Mir docking mission.) | ||
| 19 | Fri | Tri-Valley Stargazers meeting 7:30 PM Unitarian Universalist Church in Livermore, 1893 N. Vasco Road, Livermore. (3/4 mile north of I-580). |
| 20 | Sat | Open House at The Dark Site. Meet at the corner of Mines and Tesla Roads, Livermore, at 6:00 PM |
| 21 | Sun | Aldebaran 0.3° south of Moon (occulted in Asia). |
| Mars Global Surveyor begins aerobraking. | ||
| 22 | Mon | TVS Planning Meeting 7:00 PM Round Table Pizza, 1540 First St., Livermore (in Orchard Supply/Longs/Safeway shopping center). |
| Autumnal Equinox 4:56 PM | ||
| 23 | Tue | Last Quarter Moon 6:35 AM |
| Delta Cephei at maximum 12:42 AM | ||
| 24 | Wed | Io transits Jupiter 12:32 AM; shadow transits 1:33 AM |
| Io occulted by Jupiter 9:44 PM, reappears from eclipse 1:03 AM | ||
| Europa transits 10:55 PM to 1:45 AM; shadow transits 12:56 AM | ||
| Ganymede occulted 1:30 AM | ||
| 25 | Thu | Io transits Jupiter 6:59 to 9:17 PM; shadow transits 8:02 to 10:19 PM |
| 26 | Fri | Io reappears from eclipse 7:31 PM |
| Europa reappears from eclipse 10:38 PM | ||
| 27 | Sat | Excellent weekend for observing: No Moon until 3:22 AM |
| Chi Cygni at maximum brightness (about 5.2, up from about 12 over an irregular period of about 407 days). | ||
| Asteroid 8 Flora (mag 8.1) at opposition. | ||
| 28 | Sun | Ganymede's shadow transits Jupiter 7:48 to 11:26 PM |
| 29 | Mon | Callisto eclipsed by Jupiter 10:29 PM |
| October 1997 | ||
| 1 | Wed | New Moon 9:51 AM PDT. |
| Io occulted by Jupiter 11:33 PM | ||
| Europa transits 1:19 AM | ||
| 2 | Thu | Rosh Ha-Shanah (Jewish New Year 5758, at sunset 6:43 PM). |
| Date (00 UT) | R.A. (2000) | Dec | El | Sky | Mag |
| 09-09 | 07h56.2m | -28° 15' | 58° | M | 5.6 |
| 09-14 | 07h59.5m | -30° 19' | 60° | M | 5.7 |
| 09-19 | 08h02.5m | -32° 25' | 63° | M | 5.8 |
| 09-24 | 08h05.1m | -34° 31' | 65° | M | 5.9 |
| 09-29 | 08h07.3m | -36° 38' | 68° | M | 6.0 |
| 10-04 | 08h08.9m | -38° 46' | 70° | M | 6.1 |
C/1997 N1 (Tabur)
| Date (00 UT) | R.A. (2000) | Dec | El | Sky | Mag |
| 09-09 | 11h54.8m | +32° 11' | 29° | E | 9.5 |
| 09-14 | 12h26.3m | +34° 47' | 34° | E | 10.0 |
| 09-19 | 12h58.8m | +36° 43' | 39° | E | 10.5 |
| 09-24 | 13h31.6m | +38° 00' | 43° | E | 11.0 |
| 09-29 | 14h04.0m | +38° 41' | 47° | E | 11.4 |
| 10-04 | 14h35.5m | +38° 52' | 51° | E | 11.8 |
C/1997 O1 (Tilbrook)
| Date (00 UT) | R.A. (2000) | Dec | El | Sky | Mag |
| 09-09 | 13h33.8m | +04° 05' | 36° | E | 11.9 |
| 09-14 | 13h39.7m | +05° 16' | 33° | E | 12.1 |
| 09-19 | 13h45.6m | +06° 22' | 30° | E | 12.2 |
| 09-24 | 13h51.4m | +07° 24' | 28° | E | 12.4 |
| 09-29 | 13h57.1m | +08° 24' | 26° | E | 12.6 |
| 10-04 | 14h02.8m | +09° 23' | 25° | E | 12.7 |
Another new comet has been discovered by a Southern Hemisphere observer. Mean while, Comet Hale-Bopp rolls into the morning southern sky for many North American observers. Comet Tabur (C/1 997 N1), which is behind the sun and will soon appear in our evening sky, has shown some diffuseness lately. This indicates that it may be fading out- only time will tell. Finally, three more comets have been found by the solar-orbiting SOHO satellite, bringing its total to twenty. None of these comets have been seen from the earth and most of them belong to the Kreutz Sungrazing Group.
Justin Tilbrook of Clare, South Australia used an 8-inch reflector to discover a new comet on July 22. It was in the evening sky, just north of the constellation Corvus, and magnitude ten. Comet Tilbrook (1997 O1) is presently receding from both the earth and the sun, and therefore growing dimmer.
Comet Hale-Bopp, as seen from the earth, is pulling away from the sun and moving south. This provides a limited opportunity for Northern Hemisphere observers to get their last look at the comet. From 25 Degrees North Latitude the comet will be seen best in mid-October when it will be 20 degrees above the southern horizon at morning twilight. This is why this is possible. In early September Comet Hale-Bopp is low in the southeast at astronomical twilight. With each passing morning it is higher in the sky at astronomical twilight; this is because it rises earlier each day while the sun rises later, giving the comet additional time to climb. After mid-October this daily gain begins to be offset by the comet's continued southern motion, and by the end of the year it will no longer be visible. A final encore presentation of the comet for those at 25 Degrees North Latitude occurs in early 1998 when the comet winds northward again, peeking over the southern horizon at evening twilight.
Observers further north will not be quite as lucky. At 40 Degrees North Latitude Comet Hale-Bopp will be best seen between mid-September and mid-October, when it will be rising above your ESE horizon at morning astronomical twilight. It will not get more than five degrees high in dark sky on any of these mornings. If you live between any of these aforementioned latitudes, you can probably figure out your own comet watching situation. In any event you'll need a low southeastern horizon, clear air and probably a medium-sized telescope to view the comet, which is about 300 million miles away.
Orbital Elements
| Object: | Hale-Bopp | Tabur | Tilbrook |
| Peri. Date: | 1997 04 01.13800 | 1997 08 15.4779 | 1997 07 13.2599 |
| Peri. Dist (AU): | 0.9141405 AU | 0.395469 AU | 1.373622 AU |
| Arg/Peri (2000): | 130.58915 deg. | 344.2126 deg. | 336.0222 deg. |
| Asc. Node (2000): | 282.47069 deg. | 147.6169 deg | 231.1502 deg. |
| Incl (2000): | 089.42943 deg. | 085.9685 deg | 115.8011 deg. |
| Eccen: | 0.995 1172 | 1.0 | 1.0 |
| Orbital Period: | ~2500 years | Long Period? | Long Period? |
| Ref: | MPC 295 68 | MPC 302 44 | IAU Cir. 670 7+ |
| Epoch: | 1997 06 01 | 1997 08 15 | 1997 07 13 |
| Absol. Mag/"n": | -1.0/4.0 | 10.0/ 4.0 | 8.0/4.0 |