The International Occultation Timing Association's 16th Annual Meeting at the Arthur J. Dyer Observatory,  Brentwood, Tennessee

September 12-13, 1998


24" Cassegrain Mount


Arthur J. Dyer Observatory





Meeting Attendees


Terri McManus with meeting attendees



24" Cassegrain Telescope


Highlighta of the 16th

1998 IOTA Annual Meeting

Arthur J. Dyer Observatory in Brentwood, Tennessee

By Richard Nugent, Executive Secretary


The 16th annual meeting of the International Occultation Timing Association was held Saturday and Sunday September 12-13, 1998 at the Arthur J. Dyer Observatory in Brentwood, Tennessee, just south of Nashville, Tennessee. This was a perfect meeting place since it was the day after a rare triple grazing occultation , which included  the spectacular Aldebaran graze. 

 The meeting was  arranged by IOTA member Scott Degenhardt working with the Observatory’s Director, Dr. Douglas S. Hall. Scott Degenhardt had also done an excellent job in arranging the triple graze expedition along with providing hotel information for travelers outside of the Nashville area on his web site.

 Twenty four members were present at the Saturday meeting and seventeen members at the Sunday meeting and included:

Officers President David W. Dunham from Maryland, Treasurer and Secretary Craig and Terri McManus, Occultation Newsletter (ON) editor Rex Easton, Vice President for Grazing Occultation Services Richard Wilds all from Kansas. Other members present included: Wayne Warren from Maryland, Scott Degenhardt, Chris Reese, Dudley Pitts, Ben Hodges from Tennessee, Bob Sandy, David Neuenschwander, Wayne Clark, Nancy Clark from Missouri,  Benny Roberts from Mississippi, Richard Nugent from Texas, Bob Manske, Neil Simmons from Wisconsin, Danny Falla from California, Jim Roe, Yvonne Roe from Oaxaca, Mexico, Chuck Bueter from Ohio, Mike Nicholas from Kentucky, and Derald Nye from Arizona.   

 Prior to the start of the meeting, a brief history of the Dyer Observatory was given by its Director, Dr. Douglas S. Hall. The Observatory is operated by Vanderbilt University and has been very active in past years. One of the main instruments is the  Seyfert 24” f /17.5 Cassegrain telescope named in honor of  Carl Seyfert who first recognized active galactic nuclei in the 1950’s (Seyfert galaxies). The Observatory also contains an outstanding library and is the most complete astronomical library in the southeast United States.  Unfortunately, Dr. Hall mentioned that at the present time the Observatory is under utilized, and has offered it to visiting astronomers with research proposals.   

 David Dunham opened the meeting with a discussion about the 19 year Meton cycle and the 18.6 year Saros cycle. He compared the similarity of grazes from 19 years ago over southern California to the early morning’s triple graze.  He mentioned that the Aldebaran and ZC 680 grazes were observed successfully in 1979 despite the fact that predictions were not as accurate back then.  Triple graze history was made the night of September 12, 1998 as several observers recorded 3 grazing occultations - ZC 680 (m=6.7), Aldebaran (m=0.8) and SAO 94056 (m=8.3). The only previous successful triple graze observation in one night was the one involving the same three stars observed by Richard Nolthenius on Sept. 12, 1979.

 David Dunham showed a press release he distributed in the Baltimore area encouraging the general public to record the Aldebaran occultation with camcorders. The press release also asked camcorder observers to record a local station, WBAL, before and after the occultation so that their tapes could be calibrated with radio station WWV time signals. 

  Results of the September 12, 1998 graze reported at the meeting:              

 Lexington, Kentucky: Dunham/Warren - had equipment problems but did obtain timings for each of the 3 grazes.

 Nashville, Tennessee - Degenhardt, et. al -10 observers participated, saw and recorded all 3 grazes. Scott Degenhardt described how his Dodge Caravan flushed out numerous deer (for the other drivers) along the 125 mile round trip to all three graze sites along unchecked Tennessee and Kentucky back roads.

 Memphis, Tennessee - Clouded out.

 David Dunham briefly discussed the new reference catalogs being used for IOTA predictions, the HIPPARCUS (HIgh Precision PARallax COllecting Satellite, 118,000 stars) TYCHO (over 1 million stars) and ACT (nearly a million stars) catalogs.  The low standard errors of the HIPPARCOS positions create a reference frame (on the order of a few milliarcseconds)  of unmatched precision. This has helped tremendously in the prediction of asteroid occultations.  Previous to the HIPPARCOS and ACT catalogs, asteroid occultation predictions used the GSC 1.2 catalog (average standard error = 0.3 arcsecond) which was a re-reduction of the original GSC using the Position and Proper Motion (PPM) catalog reference frame. Along with “last minute CCD astrometry” the predictions could only pin down the asteroidal shadow to 2 or so path widths.  Last minute CCD astrometry updates usually have large standard errors of  0.2 - 0.4 arc seconds and thus these observations cannot always be used for such occultation predictions especially when a large number of observers are planning extensive travel to an uncertain shadow path.  With the new HIPPARCOS and ACT reference frames, experience has shown asteroid occultation predictions are now usually accurate to within ½ path width. With the highly accurate observations provided by meridian circle observations of the target star and asteroid, along with the HIPPARCOS and ACT  catalogs as reference frames, asteroid occultation predictions can now be made accurately a week or more in advance thus allowing a much narrower uncertainty in the path. 

 David Dunham also mentioned that E. Goffin has put together a temporary “All Sky Catalog” for use in the 1999 asteroid occultation predictions complete to about m = 10. Wayne Warren cautioned that the proper motions in this catalog are not in the standard format. He also said that problems with the double stars in this catalog are being identified. These problems are being worked on  by Mitsuru Sôma in Japan. Richard Wilds mentioned that when a target star in a grazing occultation expedition is actually a double, this can cause a disaster, if the components are more than a couple of tenths of an arc second apart and this is not taken into account properly in the predicted profile.

 David Dunham passed out a compiled list of all observed asteroid occultations from 1958 until 8-17-98 containing 181 occultations.  Dunham also showed derived asteroid profiles of some recent successful events:  1437 Diomedes, 11-17-97, 5 chords, Japan

              105 Artemis , 12-4-97, 7 chords, Arizona

               39 Laetitia, 3-21-98, 14 chords, Southern Europe

               25 Phocaea, 5-13-98, 4 chords, Phoenix

               248 Lameia, 6-27-98, 5 chords, South Africa

Dunham mentioned that the Astronomical League (AL) is interested in helping IOTA identify potential asteroid occultation observers. They have requested a short form asking for observer’s location, telescope, equipment, etc. to be published either in the REFLECTOR newsletter or distributeed by other means.  Along these lines Alan MacRoberts of Sky and Telescope asked that IOTA members help reduce video tapes  from casual observers of Aldebaran type occultations.

Dinner was from 7:15 to 8:55 PM. Following dinner, Derald Nye showed a video of the rare Venus/Jupiter occultation by the Moon on April 23, 1998 at Acension island in the South Atlantic. Although thin clouds often hampered the view, all 4 events were clearly seen and recorded.

Richard Nugent then showed his video of the Baily’s Beads phenomena from the February 26, 1998 total solar eclipse southern limit on the island of Curacao.  At his site, he was joined by IOTA member Chuck Herald from Austin, along with Jay Miller from Bethesda Maryland,  Isao Sato from Japan (who was after the “flash” spectrum). Wayne Warren was set up approximately 1 km north of Nugent’s site. Under clear skies, the Beads on the video clearly showed that Nugent was just outside the path of totality as one single Bead did not vanish during mid eclipse.  The success of this Baily’s Beads effort was remarkable considering that the island was covered with rain showers earlier that morning.

 David Dunham described his results from the northern limit of the February 26, 1998 eclipse from a small Venezuelan island. His expedition was arranged and joined by Dr. Patricia Rosenzweig of the Universidad de Los Andes, Mérida, Venezuela. He briefly described the reduction procedure of solar eclipse tapes for the purpose of obtaining a solar radius. As of this date, tapes of 8 eclipses have been reduced. Due to the complexity and time required to reduce solar eclipse tapes,  funding has been actively sought by David Dunham and Wayne Warren to reduce the backlog of tapes.

David Dunham showed a long video consisting of numerous total, grazing and asteroid occultations taken by himself and by several other observers in different countries using a wide variety of equipment. Bob Sandy then showed a video of his first video graze of Aldebaran from the previous night using a Supercircuits PC-23 video camera. This is the same camera that other IOTA members are “swearing” by. (Supercircuits, One Supercircuits Plaza, Leander, Texas 78641, www., 1-800-335-9777). Scott Degenhardt showed the video of the triple graze from the night before again taken with the PC-23 video camera. Then Chuck Bueter showed the Aldebaran graze event taken with his camcorder mounted on a tripod with the digital zoom “maxed out”. Aldebaran was resolved clearly on Chuck’s video disappearing and reappearing.

Following the videos Derald Nye offered several extra time inserter boards he has used for $25 each to members who wish to build their own video time inserter. Derald mentioned that in order to complete the video time inserter, about $100-125 in parts are needed which he has a list of.

The meeting closed shortly after 11:00 PM and a brief tour of the 24” Cassegrain telescope and equipment inside the 5 ton dome was provided by Dr. Douglas Hall, the Observatory’s Director.         

          Sunday, September 13, 1998


Prior to the continuation of the IOTA annual meeting, at 9:30 AM group photos were taken outside the Observatory by Bob Sandy, Derald Nye and Richard Nugent.


David Dunham opened up the business meeting by announcing the nominations for Officers and positions within IOTA, since this is an election year.  Nominations were presented to all IOTA members by either email and publication in the ON July 1998 issue. The list of nominees were:


President                                            David Dunham

Vice President                                     Paul Maley

Executive Secretary                             Richard Nugent

Secretary                                            Craig McManus

Treasurer                                            Terri McManus

V.P. for Grazing Occultation Services   Mitsuru Soma

V.P. for Planetary Occultation Services  Jim Stamm

V.P. for Lunar Occultation Services       Walt Robinson

Editor for Occultation Newsletter          Rex Easton

 David Dunham moved to vote for the new slate of Officers and there was no opposition. The motion was seconded. Dunham then moved to close the elections. The motion was seconded.

 Next, Terri McManus presented the Treasurer’s report. Terri passed out copies of the Profit and Loss Comparison for the period 12/1/96 - 6/30/97 and 7/1/97 - 8/31/98 and the Cash Flow Report covering the time period 7/1/97 thru 9/12/98. The income/expenses showed IOTA to be in good financial shape as there is a slight positive cash flow of approximately $5 for the 12 month period ending 8/31/98.  One item elaborated on by Terri McManus was a $500 cash contribution handled by Derald Nye. Derald had become aware of some unclaimed money from an old Denver Astronomical Society checking account. After contacting current persons in the Society, it was agreed that the funds would be divided between the Association of Lunar and Planetary Observers (ALPO), the Astronomical League (AL) and IOTA. IOTA’s share was $500.   Terri  closed the Treasurer’s Report by stating that the current balance in the checking account is approximately $7,000. David Dunham moved to approve the Treasurer’s Report. Richard Wilds seconded the Motion. The Report was approved as presented. The Cash Flow report is shown below:

                    CASH FLOW REPORT

                     7/1/97 Through  9/12/98


Category Description           9/12/98


    Back Issues                             20.00

   Contributions                          682.58

   Interest Income                       132.82

   Member                                5,580.00

   OM                                              5.00

   Other Income                              1.00

   Rebate                                       70.00

   Subscriber                               770.00

 TOTAL INFLOWS                7,261.40



   Card Cost                               78.18

  Internet Cost                           235.40

  Office Supplies                       557.75

  Postage                                 1,469.70

  Printing                                 2,069.79

  Reimburse                               193.54

 TOTAL OUTFLOWS            4,604.36

 OVERALL TOTAL               2,657.04


Derald Nye presented to David Dunham three sets of ON complete to Volume 4 that he has been keeping in his garage. One copy was given to the McManuses and one will be sent to IOTA/ES. Since the ON is referenced in major astronomical journals, it was suggested that older issues be scanned and be put online like other professional journals.

IOTA’s Vice President Paul Maley was unable to attend this years meeting but was visited by Terri McManus while she came to the NASA Johnson Space Center in Houston this past summer. Maley had given Terri several suggestions to be discussed at the meeting. They are:

1.    Put the ON on the Web (with a password)

2.    Charge for predictions, ON and postage (no more freebies)

3.    Search for grant money, need more fundraising

4.    Need a business plan

5.    Need ways to increase membership

6.    Work with Foundations to raise funds

7.    Awards for Observers similar to the Messier and Herschel awards

There was discussion among the attendees about Paul Maley’s suggestions and several were debated directly.  Craig McManus continued the discussion and passed out a list of 27 parties (many in former communist countries) that currently get the ON  at no charge. This represents 10% of postage and mailing costs, since most of these parties are overseas.

David Dunham said the current version of the IOTA Occultation manual should be converted into an easier format for distribution. The current version is an ASCII text version compressed in a zip file on the IOTA web site, however it mangles the equations and tables. Wayne Warren will look into converting the manual to a more flexible format.  The chapters on asteroid occultations and video applications will be rewritten and updated.

Craig McManus described that the North American asteroid occultation supplements were very expensive to print and mail and suggested only sending them out by request only. David Dunham suggested putting them on a password protected website, the details to be studied ASAP. Terri McManus suggested that any IOTA publication be put on a hidden website with a password for IOTA members. Without such password protection, there would be no reason to join IOTA. Scott Degenhardt offered to scan the North American 1999 asteroidal occultation charts and put them on website he has containing some 15 megabytes of space.

The discussion continued about the world going on line by the members present at the meeting. With the widespread popularity of the Web, David Dunham, Craig and Terri McManus suggested (and it was agreed by the members present) that all future IOTA predictions and the ON  be put on a hidden URL to save the high costs of postage and printing. Following this discussion about placing IOTA publications on-line, David Dunham and the McManuses suggested a new IOTA membership fee structure be proposed and adopted:


 New membership fee    Membership type               Includes   

A.  $15.....................On line membership................Supplements

B.  $30..................... North America Paper..............Supplements

C.  $35..................... International Paper..................Supplements

Subscriptions Only:

 D.  $10.................... Online............... Different password/No supplements

 E.   $20.................... N. America paper..........No supplements

 F.  $25.................... International paper........No supplements

 Additional membership and subscription levels may be needed as more experience is obtained with the new fee structure and member input.

 David Dunham then went over the list of the 27 parties (mostly international) who currently receive free paper mailings of IOTA publications and supplements.  In discussions with those present, David decided who should receive “drop letters” based upon how they would fit into the proposed new A thru F fee structure above based upon their need and online capability.

 The proposed online membership/supplements will now allow ON editor Rex Easton to put timely articles on line immediately. Hard copies of the ON will continue to be mailed as before to non-online members/subscribers. Rex Easton suggested that all IOTA website/online material be put on a master website such as www.  with links to all other IOTA websites for occultations, grazes, etc. Such a move would place keywords such as IOTA, Occultation, asteroid, graze, etc. available on search engines making it easier for the casual observer to locate rapidly IOTA information.

 Craig McManus suggested Certificates be sent to observers who complete their first grazing occultation. This would help promote IOTA and assist in marketing additional IOTA activities. The attending members agreed with this idea.

 Derald Nye suggested plans for including IOTA as a beneficiary in people’s wills so that useful computer/telescope/video equipment can continue to be used to help meet IOTA objectives.

 David Dunham briefly discussed (and presented handouts)  tables and charts showing thirty-three  grazes brighter than m = 6.0 and several asteroid occultations visible North America during 1999.

 David Dunham moved to close the business meeting at 12:35 PM. Craig McManus 2nd the motion and the meeting was adjourned.  Attendees then went out for lunch before traveling home.


IOTA's Annual Meetings


The International Occultation Timing Association is the primary scientific organization  that predicts, observes and analyses lunar and asteroid occultations and solar eclipses.  IOTA astronomers have organized teams of observers worldwide to travel to observe  grazing occultations of stars by the Moon, eclipses of stars by asteroids and solar eclipses since 1962.