The International Occultation Timing Association's 36th Annual Meeting

in conjunction with the North East Astronomy Forum (NEAF)

Suffern, New York, April 20, 2018

by Richard Nugent, Executive Secretary

The 36th annual meeting of the International Occultation Timing Association was held Friday April 20, 2018 at the Crowne Plaza Hotel in Suffern, New York. The meeting was kindly hosted by the organizers of the NEAF Imaging Conference. NEAF is the world’s largest Astronomy Trade Show.

The meeting schedule, links to presentation files are located on the IOTA web site meetings page:

(open any image in new tab to see full size version)

Attendees: President Steve Preston, Vice President Dr. Roger Venable, Executive Secretary Richard Nugent, Drs. David and Joan Dunham, Bob Auburger, Bob Baer, Rick Bria, Al Carich, Steve Conard, Lynn Dorsey, Bob Dunford, Frank Dempsey, Timothy Guy, Ted Frimat, Tim Gong, Kevin Green, Chuck Herold, Roxanne Karmin, Mike Kentrianakis, Russ McCormick, John Moore, David Oesper, Luca Quaglia, Ned & Lynn Smith.

9:10AM – Meeting start

Vice President Dr. Roger Venable opened the meeting and welcomed everyone to the meeting. The attendees introduced themselves, described their backgrounds and current research.

Business meeting:

Treasurer Chad Ellington (talk presented by Roger Venable) presented IOTA’s membership status. Currently there are 17 USA print subscribers plus 1 outside USA, 69 online subscribers, total subscribers is 87. This represents a net increase of 20 members since last year. The IOTA email list sever has over 700 members.

The low no. of paid members could be explained by the fact that IOTA predictions, methods, techniques and results are all online free. IOTA's Journal of Occultation Astronomy (JOA) is only available to paid members.

Expense report: A summary of the year’s bank balances are:

Starting Balance:                   $10,496.81  2017 Sep 07 (Includes funds donated for a special asteroid satellite award)

Ending Balance                       $8,220.84 2018 Apr 11

Net Decrease in Balance:       $2,275.97

 The breakdown of this past year’s budget is:

          IOTA-VTI Royalties: $72 (down $320 from last year)

         PayPal Balance         $1,872.78 (down from last year due to layout/printing costs finally paid for several back issues)

Major Expenses:

             JOA print cost $891

.............RunCam advance - $1,300 (IOTA buys these cameras in bulk with the focal reducers/adapters and then sells them as a package)

              -Awards: 412.75 (from last meeting-includes postage to foreign countries)

The JOA is currently being published on time. More articles are needed and people are encouraged to write them. The new password access for downloading the JOA is working, however many folks have trouble remembering passwords.

Technical sessions:

Brad Timerson (talk presented by Roger Venable) "7 months of Asteroid Occutations in North America". A chart was showed how the total # of North America asteroid observed events observed from 2007-2018. For 2018 to date: 176 positives, 420 misses, total = 596. Any observation, whether a positive or miss, is still an observation that has to be recorded and then plotted on a sky plane and then uploaded to the North America Asteroid Results page.

The next chart showed the number of chords attempted per observer. Through April 2018, there were 88 (1) chord observations, 44 (2) chord observations, 8 (4) chord observations, and events with more than 4 chord observations was 16. Next Roger showed the best observed events since the last meeting in September 2017 including comparisons to shape models. It was noted that Brad does a fine job of fitting chords in comparison to shape models.

Roger talked about next years "Sirius Occultation - 19 February 2019 by the 7km asteroid 4388 Jurgenstock". Sirius if the brightest star in the evening sky. The diffraction effects will likely make the event not appear instantaneous. The path goes from Baja California to Canada. Southern Arizona will have Sirius at the highest altitude in the USA. Roger next showed events in which the occulted star was brighter than m = 8.0, including 433 Kelena occulting a 4th magnitude star in September along the east coast of the USA. He then showed events in which asteroids have known moons including the recently discovered moon around 113 Amalthea on March 14, 2017.

Dr. David Dunham spoke about the best graze events from the previous IOTA meeting in September 2017 through the end of 2018. He showed the results of the 2017 Thanksgiving evening graze he and Joan did with a 25% illuminated crescent moon. Their 10 events plotted had an excellent match compared to the LRO (Lunar Reconnaissance Orbiter) profile. An Aldebaran graze occurred on March 22, 2018 over the town of Nain, Labrador (population 1,424, near their airport). A graze the night before the meeting on the way to NEAF occurred on April 19, 2018 of a 7.3 mag star, 19% Moon. They were thinking of doing the graze, but decided to skip it at the last minute.

David showed (and will be offering at the NEAF conference) a handout of grazes occurring within 500km of the NEAF conference through July 26, 2018. The last Aldebaran graze in the current series will be July 10, 2018 from Ontario over the Great Lakes through Minnesota. The next Aldebaran graze series isn't until 2033.

David then spoke about determining the "Edges of the Path of Totality for the August 21, 2017 eclipse (Historical Context)". This talk was given at the American Astronomical Society 231st meeting on January 9, 2018 in Washington, DC. David's first total eclipse was March 7, 1970 and he observed it from a short distance inside the south limit. He talked about historical attempts to measure the solar radius including data he analyzed from the 1715 and 1979 eclipses. He re-analyzed the data vs. predictions to see if there were any long term changes in the solar diameter. In determining the solar diameter, the Sun's edge needs to be defined. The main question in determining the Sun's edge is the wavelength analyzed.

Early IOTA efforts to measure the Baily's beads was by recording them projected on a screen. Alan Fiala in 1983 Jun 11 made the first video recording of the projected beads. The method has been refined over the years and time inserted video is currently the standard. Among the eclipses he discussed observations from: 1715 eclipse over England, the Jan 24, 1925 total eclipse southern limit over New York City and the June 11, 1983 eclipse over Java in Indonesia. The Feb 26, 1998 eclipse - he showed his results of the diameter- a reduction which averaged 0.20" 0.04" as compared to the standard solar radius. He discussed the efforts to get citizen participation for the Aug 21, 2017 eclipse and the observations at the southern and northern limits including the use of smart phones. There weren't enough volunteers to reach the goals of determining historical accuracies of the solar diameter. He mentioned future eclipse plans will include the flash spectrum technique (first used by the Japanese in 1970) and video targeted at certain wavelengths.

David then showed a high definition DSLR color video by Fred Bruenes from the Aug 21 2017 eclipse showing beads and  prominences.

David next showed how he and Joan did the 369 Aeria Feb 18 2018 occultation of the "A" component of eta Oph, (m = +2.0) double star over Australia. The prediction he made included taking into account the actual orbital motion of the barycenter (in addition to proper motion) which he made to 0.01" accuracy. Along with John Broughton near Queensland they set up a total of 12 stations (Broughton-7, Dunhams-5). In driving to the stations they did have issues with kangaroos !! Results - John had misses from all his stations and the Dunham's had 3 positives. He showed the video from station 2 that had a 2-sec event.

David next presented "Improving Asteroidal Occultations Predictions using Recent Past Occultations by the Same Object", a talk he gave at the 8th International Workshop & Eclipses at Istanbul, Turkey earlier this year. The Gaia satellite 1st release has provided over a million accurate star positions. The US Naval Observatory combined these with Hipparcos and Tycho positions to provide better proper motions and this resulted in the UCAC5 catalog. Using recent asteroid occultation observations, this provides a very accurate position of the asteroid which can be used to refine the orbits for future predictions. They also attempting the Regulus/268 Adora occultation. Luckily an Adora occultation was observed from Great Britain earlier; this provided an updated accurate position of Adora to refine its orbit.

But...the event was in the tropics of Indonesia that typically has bad weather. During the 3-sec occultation, they recorded Regulus's 12th magnitude companion first discovered from the 2005 Regulus occultation.

He also mentioned the Gaia data release (DR2) planned for April 25, 2018 which will include proper motions and positions from some 15,000 asteroids. Observers are encouraged to report observations of asteroid events to help refine orbits of future events of the same asteroid.

12:00 Noon - Lunch, 1:45pm- Meeting continues - Breakout Sessions

This year’s meeting has a different format from previous years. After the above business meeting and morning presentations, the group met in small “brainstorming” sessions to talk about recent developments in equipment, software and related techniques, plus discuss new ideas.

Some of the sessions were:

           Joan Dunham demonstrated the IOTA's video capture method to a Windows 10 computer stick.

           David Dunham discussed setting up remote (pre-pointed) telescopes & hardware. And he talked about several experiences setting up scopes at night including home owners and Police. He also talked about the issues with putting telescopes in luggage, dealing with airport security, leaving notes at remote stations for passerby's, etc. David demonstrated setting up the Orion 90mm telescope plus John Broughton's paver mount and other equipment.

         Other small sessions included demonstrating Limovie's features, planning remote stations and video/timing capture using computers.

5:00 pm... the meeting ended and IOTA's NEAF volunteers moved equipment to Rockland Community College for IOTA's NEAF booth setup.

The minutes of IOTA's annual meetings are at:


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.