The International Occultation Timing Association's 20th Annual Meeting
at Rice University, Houston, Texas
October 19, 2002
Highlights of the 20th IOTA Annual Meeting
Rice University Campus, Space Science Building
by Richard Nugent, Executive Secretary
The 20th annual meeting of the International Occultation Timing Association was held Saturday, October 19, 2002 at the Rice University Campus, Space Science Building, in Houston, Texas. This location was chosen since IOTA President David Dunham was already attending the World Space Conference in Houston this same week and it was convenient for some of the other IOTA officers as well.
Ten members and attendees were present at the meeting:
President David W. Dunham from Maryland,
Vice President Paul D. Maley from Texas,
Executive Secretary Richard L. Nugent from Texas,
Secretary Treasurer Art Lucas from Oklahoma,
Dr. Harry Bates from Maryland,
Richard Wilds, Dr. Gilbert Parks from Kansas,
Rocky Harper, Don Stockbauer, Brian Cudnick and Matt Delavoryas from Texas.
At 9:30 AM, President David Dunham opened the meeting and asked the attendees to introduce themselves. Following the introductions, Executive Secretary Richard Nugent asked the attendees to sign in to the Executive Secretary’s record book which has photos and Minutes of the past meetings going back to 1998. This history file will be maintained by Nugent for IOTA history purposes.
President David Dunham briefly mentioned about the before and after astrometric tests for asteroid occultation predictions program being carried out by Rui Goncalves and others in Spain and France. In this technique, Goncalves is imaging the asteroid and target star just before and just after the predicted occultation. For 25 Phocaea recently, he reported a standard error of just 0.012" in the asteroid's position, which corresponds to 1/10th the diameter of the asteroid. Using the UCAC-1 catalog, the standard errors rose to 0.05 - 0.07", still very impressive for a CCD camera and small telescope. He also says the USNO A2.0 catalog gives errors 2-3 times worse. Goncalves reported that a more sophisticated astrometric reduction model was the key to improving the results.
Vice President Paul Maley, reported on IOTA’s continued tax-exempt status. Everything is fine with IOTA’s records with the State of Texas and a quick check on the internet by Nugent confirmed this, as IOTA is a non profit corporation in good standing with the Secretary of State in Texas. Copies of these good standing letters are kept in the Executive Secretary’s file.
Treasurer Art Lucas gave a report of IOTA’s financial status. Summary of balances are:
Starting Balance: July 2001 $6,701.76
Ending Balance: October 2002 7,335.59
Total Checks written 2,631.06
Lucas reminded everyone to check their mailing labels for their own dues expiration date. Some members are way ahead on their dues, and the credits will not be refunded. Currently when a dues check arrives, it is entered into six different databases. Art Lucas will investigate converting the current bookkeeping system to Microsoft Access, a much simpler system that would streamline the accounts and finances.
Lucas also mentioned that Occultation Newsletter (ON) editor John Graves has a lack of material for publishing and encouraged IOTA members to submit their articles/observations, since this is the medium that IOTA maintains a permanent record of its continuing activities.
A long discussion followed on the methods and strategies IOTA can and should use to try to encourage and recruit new observers for occultation activities. President Dunham discussed his reaching out to colleges/universities to excite young people and students with occultation events. Occultation events happen all the time and they are usually spectacular to first time observers. This can provide great educational opportunities for students and amateur astronomers alike, plus the added benefit of knowing they are making a useful scientific contribution. One idea was a science project for a student. This could be a grazing occultation expedition or an asteroid occultation plus data reduction. Dunham also spent the previous week here in Houston attending the World Space Congress, which did offer sessions on education. Dunham brought up the idea of using occultations at one of these sessions where one of the presentations mentioned using total solar eclipses as a focus for space education.
Long time IOTA member Richard Wilds explained how a Kansas company, A Tech, is trying to recruit and bring younger people into astronomy by exciting them with active solar system research opportunities. A Tech is in the process of setting up a National Research & Educational Outreach Program. He and his colleague, Dr. Gilbert Parks (A Tech President and CEO) are negotiating with NASA & NSF to start such a program nationwide. The prototype system they would like to install in colleges/universities is similar to that of the current HART (Heartland Astronomical Research Team) program. This advanced telescope system features a 20" reflecting telescope, image intensifier, GPS and time insertion capability plus a high resolution monitor and DVD Recorder for real time views and direct video recording that can obtain deep images to a limit of 18th to 20th magnitude in digital form to 0.02 second accuracy. Wilds showed videos of telescope field of views using the image intensifier. Several objects were shown demonstrating detail in Messier and NGC objects, spiral arms in M51, and structure in M8, M20 and several star clusters with telescopic meteors and satellites moving through. This video easily matched or exceeded the visual capability of an observer in a dark sky with the same telescope. The capability of bringing a dark sky view to young people is important in an urban light polluted sky to impress upon them the wonders of observational astronomy. Wilds also presented one his many TV interviews depicting an important upcoming occultation event. Richard Wilds claims that if he can get on television for an interview related to an occultation event, that anyone can. The central plan is to remind NASA that their current asteroid radar observations are limited to NEOs and the inner region of the Main Asteroid Belt. The A Tech program would deliver detailed information about asteroid size and shape from the NEOs through the Main Asteroid Belt, and out to the Trojans, Centaurs and Kuiper Belt. This would be a significant improvement over the current options and the publicity generated for NASA would also be helpful to all involved.
Obviously, negotiating with NASA involves politics. Wilds and Parks demonstrated how building a nationwide system similar to HART could "create jobs." There would be acquisition costs (land, equipment), training and even security in setting up and maintaining such a network. A pilot project has already been funded at South Carolina State University using a completely mobile asteroid hunting Image Intensified GPS Time Inserted Video System. The estimated cost per unit is approximately $50,000, and this not only includes equipment, but travel and training costs. IOTA appears to be well placed to play an exciting role in the project. Dr. Parks is meeting at NASA Headquarters in a week with senior NASA administrators. A larger meeting is tentatively planned for December 2002 [but had not taken place as of the end of February 2003]. Dr. Dunham and Wilds are scheduled to be in attendance at this meeting. A nationwide A Tech Program with key IOTA support could soon make asteroid research a major part of NASA's solar system research and educational outreach opportunities.
Dr. Harry Bates made a presentation on, "Observing Lunar Occultations as Student Astronomy Projects". He showed ways that Physics and Astronomy Departments could be combined to include occultation projects as part of their curriculum. The basic idea was more students = more data = more chords, plus the spin off result = more interest!! Dr. Bates' power point presentation was well done and could be used effectively by other interested teachers/educators. Dr. Bates even suggested schools could eventually have student chapters of IOTA. This concept of recruiting new IOTA members is extremely important, as new blood is desperately needed to continue occultation studies.
On the issue of security, Richard Wilds mentioned that he usually places able-bodied males at the ends of a grazing occultation line. In his occultation expeditions, observers have hand held CB/2-way radios for communication, and usually notify the local authorities (Sheriff, Police, etc.) so as to avoid any confrontations during critical observation windows. Case in point: if the local authorities are notified, then phone calls from unsuspecting residents can avoid patrol cars from driving to the occultation site and causing a light pollution/conflicts scene. Several attendees told stories of experiences with police cars driving up, local “curious” residents and the like. Maley mentioned that many schools do not allow or are very cautious in allowing telescope set ups on their property or for school functions/star parties because of the liability issue. The basic thought agreed upon is to maintain a level of awareness and security during occultation expeditions so as to keep the area/unsuspecting residents safe and friendly.
Brian Cudnick, discussed the ongoing lunar meteor impact observation program. During observation of the recent Perseids in August 12, 2002, 55 candidate impact events were observed/videotaped. Cudnick would like to see a program started that would continuously monitor the dark side of he Moon monthly from age 2 days to 6 or 7 days for possible meteor impacts events. He also has submitted to NASA a proposal to have 10 people monitor the Moon these days out of every month. Toward this purpose, he created definitions in order to maintain a high level of certainty from real events vs. spurious “cosmic ray” or other false events. The definitions are:
CONFIRMED EVENT: The observation is 99% confident,
Observed by 2 or more observers,
Separated by at least 30 miles,
Time of event ±1 second,
Position of event ±3 degrees on lunar surface.
TENTAVELY CONFIRMED EVENT:
The observation is 95% confident,
Observed by 2 or more observers,
Separated by less than 30 miles,
Time of event ±3 seconds,
Position of event ±5 degrees on lunar surface.
PROBABLE EVENT: Highly probable but not confirmed,
Observed by a single observer,
Appears in two or more video frames,
Has stellar profile, » 80% confident.
CANDIDATE EVENT: 50% confidence level,
Observed by a single observer.
Art Lucas showed his power point IOTA presentation made earlier this year for the Astronomical League’s annual Convention in Salt Lake City, Utah. The theme of the presentation was to describe what equipment is needed for a video occultation observation along with the reduction techniques used to pin down the event times to 0.03 seconds. Toward calibrating the WWV tones, Lucas demonstrated oscilloscope patterns of the signal and the various delays in receiving the signal from Ft. Collins, CO to various locations within the US. For example, from Ft. Collins to Stillwater, OK, the delay was 20-25 milliseconds, from the Hawaii transmitting station at 20 Mhz, the delay was over 100 milliseconds.
At 12:30PM, the attendees headed out for lunch. Following the lunch break, David Dunham showed the results of the highly successful asteroid occultation of the star FK6 1115 (43, Tauri, m = 5.3) by the asteroid 345 Tercidina in Europe on September 17, 2002. Over 70 observers traveled to several countries thus making this an international effort. The preliminary size of Tercidina from the initial analysis of the over 70 chords is 99 x 93 km.
Just 3 days prior to the IOTA meeting, the small asteroid 3171 Wangshouguan was scheduled to occult the m = 4.9 star FK6 1089 z Arietis. Reports from observers indicated that the actual path shifted by a full path width south. At the time of the meeting, just 5 positive observations have come in from the Seattle, Washington area.
Dunham announced some major approaching bright star asteroid events:
3 November 2002 - 431 Nephele, HIP 18735, m = 5.9, European side: Finland, Atlantic side: New England to Texas. Path uncertainty is one path width. [that path shifted almost a path-width north; about 9 observers from West Virginia to Massachusetts, and one in Finland, timed the occultation].
10 November 2002 - 828 Lindemannia, p Aries (HIP 13165), m = 5.2, South Carolina to south central Texas. Paul Maley and Richard Nugent sought and recruited observers in the Houston area (just north of which the occultation path was expected) and Rick Frankenburger recruited observers in San Antonio, expected to be within the path. Maley showed a plot of current observer’s stations (usually their residences) on a large scale map of the Houston area. Coverage was good around Houston, but with only a few observers in the actual path and north of the path. At the IOTA meeting time, the uncertainty was one path width (53 km), however Maley noted at least one more astrometric update was expected before the occultation. [See R. Nugent’s separate article about observations of this occultation].
David Dunham made a presentation from July 17 earlier this year, “Increasing Coverage of Occultations with remote Video Stations”. He showed how use of remote video stations increases the coverage for occultations. On December 21, 2002, for the graze of t Aqr, m = 4.0 in Kitty Hawk, North Carolina, 4 observers produced a total of 8 stations, which included 4 remote video stations. Since it was in December, during the off season, the town was empty, so the remote unattended video stations were fairly safe. In addition to these stations, several stations in Georgia observed the event.
On July 15, 2002, n Virginis, m = 4.0, was observed with 5 unattended video stations near Champaign, Illinois by the 26% Moon. The video stations showed several dimming/partial events on this Spectral type M0III red giant star.
The first ever remote video station used on an asteroid occultation was made by David Dunham for 9 Metis on September 7, 2001 near Orland, California. The star was SAO 78349, m = 6.0 spectral type A2V. Dunham set up a camcorder with 50mm lens and image intensifier on a tripod and pointed it to the area of sky the target star would drift into during the occultation. He then drove some 23 miles south on Interstate 5 and video taped the event with a telescope. After returning to the remote station, he saw the battery had died, just after the occultation !! Steve Preston video taped this event from Redding, CA and had step events caused by the star’s duplicity. Each video station produced chords, and the analysis showed Metis to be elongated in shape 240 x 122 km. The target star was in fact a double star and analysis of the tapes by Frank Anet found the star components to be separated by 0.040² in position angle 343°. Further details appear in Sky and Telescope, March 2002 page 97.
An important procedure when setting up remote video stations is to point the telescope at the altitude and azimuth that the target star will have at the time of the occultation an hour or two before the occultation. This can be done by finding a star field at the same declination with an R.A. 1 to 2 hours less than that of the target star, set on that field at the right time, and then let the star drift into the field during the occultation rather than use a motor driven mount. Quick polar alignments for one-time occultation events usually result in tracking errors, and these accumulate over time causing the star to drift out of the field.
Dunham showed a video with multiple lunar and asteroid occultation events, including the first ever confirmed video of a meteor striking the Moon during the Leonid meteor storm of November 18, 1999 and the spectacular occultation of Saturn by the Moon on December 28, 2001.
Dunham noted that Sandy Bumgamer (who could not make the meeting) has developed a technique to modify the Supercircuits PC-164C camera to add manual gain control. He will make the modification for you if you send your PC164C camera to him. For additional details, contact Sandy directly at firstname.lastname@example.org .
Art Lucas read a letter from Majorie Walker and Alfred Kruijshoop from Mount Waverly, Victoria, Australia. They wanted to the meeting attendees to know how much they appreciate the assistance of Art Lucas and David Dunham in their occultation activities.
Paul Maley briefly discussed some upcoming eclipses in the continuous effort of IOTA to monitor possible solar radius variations. For the December 4, 2002 total eclipse over southern Africa, Paul is planning on recording the Baily’s Beads at the southern limit, while Richard Nugent is planning to go to the northern limit in Mozambique [That effort was not successful, but video observations at both limits were obtained in Australia, as reported in a separate article by Dunham]. In May 2003, an annular eclipse will occur over Iceland, and Maley is planning an expedition there also.
David Dunham next showed a few of the major asteroid events for 2003 visible from North America. One such favorable event is 44 Nysa on January 3, 2003 with an m = 8.0 star. The brightest event for the year is January 11, 2003, when m = 7.7 SAO 117679 is occulted by 441 Bathilde. [However, since the IOTA meeting, some brighter events were found and incorporated into the distributed 2003 predictions.] Other events will be available on IOTA’s website with updates made by Steve Preston.
Harry Bates then made a presentation “Using PC’s to Reduce Occultation Data”. Dr. Bates has been working with Ron Santana at the video center at his University to reduce videos of occultations. Santana has a video setup using software for a Mac computer. Bates showed an example reduction of an occultation done in a frame-by-frame mode. The software allowed extraction of intensity levels of stars, which then could be used in the software package MathCad to plot intensity profiles, thus simplifying the reduction of an occultation event.
Following this Richard Nugent showed a video of the asteroid occultation of the m = 9.2 star SAO 76241 by 161 Athor earlier in the week. This 5.7 second occultation was converted from 8mm video to an AVI file by a low cost software program available at Best Buy (Dazzle Video Digital Creator 80). Nugent positioned himself 15 miles inside the southern occultation limit while Dunham stayed about 2 miles inside this limit. Dunham had a miss. Ed Vinson and Mitch Brumbelow observed this event near the Midland, Texas area and had a positive observation, but had not reduced their tapes in time for the meeting.
Following this the formal meeting adjourned at 4:35 PM, while some of the attendees continued discussions afterwards.
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.