The International Occultation Timing Association's 29th Annual Meeting
Sierra College, Rocklin, California
July 16-17, 2011
Radio telescope at Korek Observatory, Iraq
Damaged domes at Korek Observatory, Iraq
135 Hertha occultation (colored lines) and inversion model
11 Parthenope occultation (colored lines) and inversion model
David Dunham's 1st remote video stations
1-meter portable telescope
Dr. Dunham, Eberhard Bredner, Mark Vincent, Dave Kenyon
Dr. Richard Nolthenius telescope setup for 90 Antiope event
IOTA-VTI position screen
IOTA-VTI timing screen
Portable 10-inch occultation telescope
IOTA-VTI front and back
Scotty Degenhardt's 2011 Homer F. Daboll award plaque
10-inch occultation telescope in suitcase
10-inch occultation telescope with video camera
David Dunham shows 10-inch occultation telescope
Walt Morgan demonstrates IOTA-VTI
Occultation Profile-90 Antiope 2011 July 19
Steve Preston and Joe Garlitz setting up telescope for 90 Antiope event. Photo courtesy Tony George
Paul Maley. Photo courtesy Tony George.
Scotty Degenhardt recipient of the 2011 Homer DaBoll award. Photo courtesy Tony George.
Meeting attendees. Photo courtesy Tony George.
Walt Morgan presents the new IOTA-VTI GPS time inserter. Photo courtesy Tony George.
Dr. Roger Venable and Paul Maley. Photo courtesy Tony George.
David Dunham setting up Mighty Mini for the 90 Antiope occultation. Photo courtesy Joan Dunham.
IOTA's Annual Meetings
Scotty Degenhardt, 2011 Homer F. Daboll Recipient
Highlights of IOTA's 29th Annual Meeting, July 16-17, 2011
Sierra College, Rocklin, California
by Richard Nugent, Executive Secretary
The 29th annual meeting of the International Occultation Timing Association was held on Saturday and Sunday July 16-17, 2011 at Sierra College in Rocklin, California. This location was chosen to coincide with the occultation of the binary asteroid 90 Antiope covering a 120-km wide path that covers northern California a few hours before sunrise on July 19, 2011.
Thirty-five (35) positive chords were obtained and the results are posted at the asteroid occultation results page:
The meeting location was kindly hosted by Dave Kenyon of Sierra College who also hosted IOTA’s 21st annual meeting in 2003. The final meeting schedule, and most of the presentation files, are located as links from Brad Timerson’s North American Observations web site:
Fifty-five persons participating in the meeting in person/from the EVO internet conference:
President Dr. David Dunham and Dr. Joan Dunham from Maryland,
Vice President Paul Maley, Chuck Herold from Texas,
Dr. Eberhard Bredner, IOTA-ES Secretary, from Germany
Tony George from Oregon,
Steve Preston from Washington,
Dan Davidson, Ted Swift, Dr. Richard Nolthenius, Walt Morgan, Derek Breit, Danny Falla, Sandy Bumgarner from California,
Dr. Roger Venable from Georgia,
Scotty Degenhardt from Tennessee,
Derald Nye from Arizona,
Jerome Berthier, Fracois Colas from France
Other on-site attendees included Hank Sielski, Mark Vincent, Earl Wilson, John Westfall, Roc Fleishman, Frederic Vachier, Joe Garlitz, Greg Lyzenga, Lampert Levy, Mark Vincent, Wayne Hopkins, John Goeschl.
Video Internet Conference (EVO) Attendees: Steve Messner, Ted Blank, Brad Timerson, Chris Douglass, John Grismore, Dr. Terry Redding, IOTA Treasurer Chad Ellington, IOTA Executive Secretary Richard Nugent, Ernie Iverson, Richard Wilds, Dave Gault, Aart Olsen, Bruce Berger, Jan Manek, Dave Herald, Steve Conard, Bruce Holenstein, Wolfgang Rothe, Rob Robinson, Hristo Pavlov, Bob Sandy, Dr. Wayne Warren, Jr., Jonathan Bradshaw, Ned Smith, Rafael Chavez, John Talbot.
9:01AM – Meeting start – Introductions
President Dr. David Dunham opened the meeting and welcomed everyone. He then asked the attendees to introduce themselves. All present at Sierra College walked in front of the webcam and introduced themselves. Then all EVO attendees with microphones introduced themselves.
Dave Kenyon of Sierra College welcomed back IOTA for this year’s meeting.
IOTA Treasurer Chad Ellington presented the income and expense report. A summary of the year’s bank balances are:
Starting Balance: $7,089.65 2010, Dec 4
Ending Balance: $6,305.00 2011, Jul 11
Net Decrease in Balance: $ 784.65
New Server: Currently a new web site is being investigated for IOTA business. Chad showed a screen shot of the proposed new format of the business page which included links to all archived ON’s (Occultation Newsletter, renamed JOA) and allowing for payment for subscriptions to ON/JOA. The old site, www.occultations.org was being paid for by Art Lucas and Lucas has suggested we move everything elsewhere to stabilize IOTA business needs.
A Google group website is currently up and running for accessing past ON/JOA issues and IOTA business. The URL is http://groups.google.com/group/iota_us. All users and access would be approved by Chad, as he would maintain the site. In this scenario, users would be able to customize their access page such as having links to the asteroid predictions, lunar graze events, software programs, IOTA-ES, RASNZ, Euraster, weather forecasts, etc.
David Dunham motioned the group to accept the financial report as presented. All attendees agreed.
This year’s presentation of the annual Homer F. DaBoll Award was made by the Award Committee Chair Dr. Terry Redding. The Homer F. DaBoll award is given annually to an individual in recognition of significant contributions to Occultation Science. “Occultation Science” is limited to actual IOTA research: total and grazing occultations, asteroid occultations and solar eclipses.
Homer F. DaBoll had a long history with IOTA until his death on March 10, 1990. DaBoll was born on May 22, 1920. He led numerous grazing occultation expeditions in the Chicago area spanning 3 decades, from the 1960’s to 1990. He was the first ever editor of Occultation Newsletter for 16 years from its first issue in 1974 thru early 1990 when health reasons forced him to pass on the Editorial duties to Joan Dunham. DaBoll was the person who came up with the acronym IOTA, International Occultation Timing Association. Members of IOTA have always held Homer DaBoll in the highest regard for his numerous contributions to occultation observations, expeditions, ON, and his many other volunteer efforts.
This year’s committee received 14 nominations. The Committee’s main objective in selecting an award recipient was to reach a consensus and not choosing someone by a majority vote. The rules allow any person to be considered for the award except for current IOTA Officers and Committee members.
The 2011 Homer F. DaBoll award recipient was Scotty Degenhardt from Columbia, Tennessee for his long time contributions to IOTA including the design and development of the multi video station deployments (Might Mini’s). These have become the standard for spreading out and maximizing coverage for asteroid events. Scotty broke all records with his December 11, 2008 occultation observations of 135 Hertha in which he obtained an unprecedented 14 chords ! The award plaque reads "Homer F. Daboll Award Presented to Scotty Degenhardt For Leading The Way In Occultation Observation Techniques To Include Scope Design, Multi-Station Deployment And Data Collection".
Scotty described how he came up with the idea of the Mighty Mini concept. In his garage one day he found a half binocular in his toolbox. It was left there 15 years earlier as he used the other ½ to make a telescope finder. He decided to try and use it as a lens for a video system and after experimenting and “tweaking it along” the “Mighty Mini” was born. The rest is history.
Dunham suggested since there is a backlog of persons entitled to receive the Homer DaBoll Award, that a 2nd award can also be given annually perhaps under a different name.
David Dunham presented a power point written by Guy Nason for the possible location of next years IOTA 2012 meeting in New Brunswick, Canada. The asteroid 52 Europa will occult a m = +11 star for an unusually long 81 seconds on August 12th UTC. It covers a 352km wide path visible only from Canada's Maritime Provinces and perhaps NE Maine. Weather prospects typically offer a 50% chance of clear skies, the best in the Europa path. A meeting there would have the full support of the RASC New Brunswick Centre. The meeting could be hosted by the University of New Brunswick with its excellent meeting facilities and favorable lodging rates. This location offers the combination of IOTA interests and a vacation of one of the most scenic locations in Canada. As an added bonus the following weekend August 17-19, 2012 is the Stellafane Conference in Springfield, Vermont, the oldest and most famous star parties in North America.
Brad Timerson has been researching the acquisition of a single IOTA dedicated domain to host most if not all IOTA web sites. Currently we have different sites for the business pages, lunar occultation/graze pages, annual meeting minutes, and other pages. The scattering of this important IOTA information could lead to problems if a server ceases to exist/have problems (as was the case for Nugent’s IOTA meeting minutes pages earlier this year). Brad found a server LibiHost.com, http://www.libihost.com/index.php which offers an excellent rate for non-profit organizations.
- Features: http://www.libihost.com/plan.php?p=21
- Price: $ 4.95 per month, $ 49.50 per year
- Local contact person for service, specific hosting plan for non-profits
And by luck, the person managing this server is located a mere 20 miles from Brad. One advantage of having our own domain would be shorter URL’s. A username/password can be set up for paid IOTA members for the business pages. Brad will continue exploring this important task for IOTA.
Executive Secretary Richard Nugent presented a summary of the minutes for last year’s 2010 meeting held in Boston, MA. Earlier this year Nugent had to move the annual meeting minutes pages (covering years 1998-present) to Derek Breit’s poyntsource.com server. The person whose server hosted the IOTA minutes website passed away in March 2011 and along disappeared the web pages. The current location for IOTA annual meeting minutes from 1998-present is:
Vice President Paul Maley talked about the status of the recently formed IOTA Middle East Section, IOTA/ME. Their web address is http://www.iota-me.com/. Their current focus is to foster and spread knowledge and observing in occultation research, especially lunar occultations. Many members have telescopes and their 1st meeting last November 17-19, 2010 in Gonbad Iran had 74 attendees. Paul has contributed 5 articles to their newsletter, Dunham has contributed articles also. They plan to expand their membership with observers from Iraq and Afghanistan.
David Dunham presented the current status of IOTA publications. One way the activity of a scientific organization can be realized is by the amount of publications in refereed journals. Since last December 2010, the following publications involving occultations/eclipses has appeared:
“Constraints on Charon’s Orbital Elements from the Double Stellar Occultation of 2008 June 22”, B. Sicardy, G. Bolt, J. Broughton, T. Dobosz, D. Gault, S. Kerr, F. B´ nard, E. Frappa, J. ecacheux, A. Peyrot, J.-P. Teng-Chuen-Yu, W. Beisker, Y. Boissel, D. Buckley, F. Colas, C. de Witt, A. Doressoundiram, F. Roques, T. Widemann, C. Gruhn, V. Batista, J. Biggs, S. Dieters, J. Greenhill, R. Groom, D. Herald, B. Lade, S. Mathers, M. Assaﬁn, J. I. B. Camarge, R. Vieira-Martins, A. H. Andrei, D. N. da Silva Neto, F. Braga-Ribas, and R. Behrend The Astronomical Journal, Vol. 141, pp. 67-83, 2011 February.
“Combining Asteroid Models Derived by Lightcurve Inversion with Asteroidal Occultation Silhouettes”, Icarus, 2011, in press.. Authors: Josef Ďurech, Mikko Kaasalainen, David Herald, David Dunham, Brad Timerson, Josef Hanuš, Eric Frappa, John Talbot, Tsutomu Hayamizu, Brian Warner, Frederick Pilcher, and Adrián Galád, The analysis of over 40 asteroidal occultations observed from 1977 to 2010, combined with lightcurve inversion models, is described. This important paper is now available at http://astro.troja.mff.cuni.cz/projects/asteroids3D/download/durech_et_al_2011_occ_paper.pdf
“Obituary: Thomas C. Van Flandern (1940-2009), Bulletin of the American Astronomical Society, Vol. 43, p. 23, 2011 June. Authors: David Dunham and Victor Slabinski, It is available at: http://aas.org/baas/obits/obit?Full_Name=Tom_C._Van%20Flandern&Date=2009-01-09
“A New Double Star from an Asteroidal Occultation: UCAC2 41168613”, Journal of Double Star Observations, Vol. 7, No. 2, pp. 129-132, April 1, 2011. Authors: Tony George, Brad Timerson, Kerry Coughlin, and Roc Fleishman, The results of the occultation of UCAC2 41168613 by (675) Ludmilla observed on 2010 October 20 from Baja California Sur, Mexico, are described. Available at http://www.jdso.org/volume7/number2/George_67_70.pdf
“TYC 2255-01354-1 Duplicity Discovery from Asteroidal Occultation by (790) Pretoria”, Journal of Double Star Observations, Vol. 7, No. 3, pp.172-177, July 1, 2011. Authors: Tony George, Brad Timerson, Bill Cooke, Scott Degenhardt, David W. Dunham, Steve Messner, Robert Suggs, Roger Venable, and Wayne H. Warren, Jr,, The results of the occultation of TYC 2255-01354-1 by (790) Pretoria observed on 2009 July 19 from Minnesota, Tennessee, Alabama, and Georgia are described. Available here: http://www.jdso.org/volume7/number3/George_34_39.pdf
“HIP 46249 Duplicity Discovery from Asteroidal Occultation by (160) Una”, Journal of Double Star Observations, Vol. 7, No. 3, pp. 178-182, July 1, 2011. Authors: Tony George, Brad Timerson, Tom Beard, Ted Blank, Ron Dantowitz, Jack Davis, Dennis di Cicco, David W. Dunham, Mike Hill, Aaron Sliski, and Red Sumner, The results of the occultation of HIP 46249 by (160) Una observed on 2011 January 24 from Nevada and Massachusetts are described. Available here: http://www.jdso.org/volume7/number3/George_40_44.pdf
“Towards A Unified Definition Of Solar Limb During Central Eclipses And Daily Transits”, International Journal of Modern Physics D, World Scientific polishing Company, June 14, 2011. Authors: Cosantino Sigismondi, Andrea Raponi, Cyril Bazin, Richard Nugent. A new simple criterion to define the timing of the Sun’s photosphere’s disappearance/reappearance from Baily’s Beads is modified. Available at: http://arxiv.org/PS_cache/arxiv/pdf/1106/1106.2197v1.pdf
2012 RASC Observer’s Handbook - Lunar occultation material has been prepared by Dave Herald and Eberhard Riedel. Jim Stamm is working on the asteroidal occultation list. Dunham mentioned they are behind schedule with this, but hope to finish and submit late next week to the new RASC handbook editor.
2011 Astronomical Calendar, Guy Ottewell, The “Occultations” chapter is written by Secretary Richard Nugent and lists occultation events visible with naked eye and binoculars, both by the Moon and asteroids.
The new Journal of Occultation Astronomy has seen two issues since it’s replacing of the Occultation Newsletter. The first issue was published near the time of the last meeting, December 2010. The second issue was published in April, and the third issue is being assembled. Two papers submitted to ON but never published will finally be published in the third issue of JOA. In the current issue of JOA, David Dunham, Hans Bode and Editor Michael Busse apologized to author Kazuhisa Miyashita for the long delay in getting his article on LiMovie published. Miyashita's article was submitted in September 2009. At that time there was no ON editor and the status of ON was unknown. A pledge was made not to let this happen again.
Paul Maley presented the status of possible funding for IOTA. He has been communicating with Bill Merline of the Southwest Research Institute (SwRI) in Colorado. The amount of actual funding is unclear but may be in the range of several thousand dollars. This would be for actual expenses only (such as airfare, rental car, hotel) and only for selected persons for selected asteroid events. The aim is to start a professional-amateur collaboration for asteroid events. If IOTA can show its worthiness and acquire excellent data on a few choice events, this may lead to future but limited funding.
Paul has identified several candidate events for this process:
704 Interamnia November 11, 2011
57 Mnemosyne March 11, 2012 - California
63 Ausonia March 21, 2012 – California to Texas
185 Eunike August 3, 2012, Baja Mexico
52 Europa August 12, 2012 Maine, Nova Scotia
856 Backlunda September 17, 2012 Florida
111 Ate October 5, 2012, South Florida
521 Brixia October 22, 2012 California to Dakotas
168 Sibyla November 25, 2012 Central Florida
Another proposal does not entail any funding for new occultation data. Instead it seeks to combine existing photometric data with existing asteroid occultation data to get better sizes/shapes of asteroids, using the KOALA method. IOTA help is sought in finding and interpreting existing occultation data and, what’s more, the occultation data will contribute to key new science results, leading to better understanding of asteroid sizes, shapes, densities and compositions.
Business Meeting closed. 12:15PM Lunch Break
1:35PM Technical Session Starts
Dr. Terry Redding gave his experiences in coordinating observers for the occultation of 217 Eudora on May 29, 2011. He routinely collaborates with Tom Campbell of Tampa, FL. Terry presents occultation reports monthly to the Palm Beach Astronomical Society located in West Palm Beach, Florida. He described the timeline on how he decided to attempt the event, how he contacted observers and how observers and interested parties (including the local CBS affiliate) expressed interest in trying this important event.
The timeline of events included:
May 9th, 5 observers were committed,
May 11th, a school science teacher joined the group
May 13th South Florida Science Museum expressed interest
May 16th Science Museum offered canned material from IOTA for CBS (TV station) and a camera, KIWI GPS for their C-14.
May 17th Science Museum advised against using the C-14 telescope citing poor tracking and little prospect of seeing “anything”
May 18th 18 stations committed
May 19th pre-point method prepared and shared
May 22nd Science Museum commits to one station
May 23rd local club member announces he has 2 Mighty Minis, PC164C camera and 2 Canon camcorders.
May 24th a club member falls off a ladder and suffered brain damage and was taken to intensive care.
May 27th Final instructions for observers
May 29th Event – a miss was recorded for most stations. IOTA members know this better than anyone so Terry had to explain the statistical nature of the predictions regardless of how accurate they maybe.
David Dunham discussed changing a large deployment at the last minute in connection with the 2011 May 29, 217 Eudora event. With the prediction looking very good, Dunham planned a series of Mighty Minis. He and Joan Dunham chose central Florida to try 9 stations covering the path center and the north uncertainty zone. One thing to consider was the weather – the rainy season starts in Florida in May and most days have thunderstorms in the afternoons. He had a Plan B depending on daily weather uncertainties while watching Occult Watcher station updates.
The Dunhams used a paper copy of the Florida DeLorme Gazetteer (detailed road atlas) on their flight comparing Google maps to see where the path limits crossed several roads they might use. No internet was available on the flight and Dunham says it would have made the process more difficult. Delays and clouds only allowed time to set up 5 video stations plus one additional station. One station was skipped due to clouds in the area. At another site the camcorder battery died before the occultation!
The result was a 1.3-path width north shift causing 5 misses and one positive chord – the northernmost station. Steve Preston had advised that this star might have duplicity and had proper motion discrepancies between catalogs. At the time of this annual meeting Paul Maley had 2 videos of possible events and would ask Tony George to analyze them.
Just 5 nights after the Eudora occultation on June 3rd, an occultation by the relatively small asteroid 1166 Sakuntala was predicted for the northeast USA with large uncertainties. Dunham spread six stations across the zone, with 4 recording the star (10.5-mag PPM 719647) – all misses. As luck would have it, Bruce Berger recorded an occultation in between Dunham’s station’s 3 and 6 which were 25km apart !!
Tony George presented a list of IOTA publications on the discovery of new double stars published in the Journal of Double Star Observations, JDSO. From January 2010 to July 2010, 4 papers were published in JDSO reporting new double stars discovered from occultations. The target stars that showed duplicity were:
TYC 4677-00696-1 occulted by 1048 Feodosia on 2008 November 18, separation unknown – visual observation
UCAC2 41168613 occulted by 675 Ludmilla on 2010 October 20, Sep = 28.3 ± 2.0 mas
TYC 2255-01354-1 occulted by 790 Pretoria on 2009 July 19, Sep = 144.8 ± 0.4 mas
HIP 46249 occulted by 160 Una on 2011 January 24, Sep = 6.5 ± 1.1 mas
The occultation by 1048 Feodosia was a visual observation made by Alan Whiteman. He made such a careful high quality observation that Dave Herald agreed that Alan did in fact observed a drop in brightness due to duplicity of the star.
A portion of Alan’s actual report is reproduced below:
“At 04:28:01.0 the magnitude 10.1 target star TYC 4677-00696-1 crisply faded but did NOT disappear. It remained at least as bright as magnitude 12.9 GSC 4677-806 located 1.7' northeast. This failure to dim the predicted 4.7 magnitudes completely surprised me and resulted in a very long reaction time that I estimated to be 0.75 seconds. (This estimate is on the tape, a couple of minutes after the event.) I .. (made) .. a conscious effort to compare the magnitudes of the two stars during the brief occultation.] Transparency was excellent and the seeing was fair since the 1.8” double star Alpha Psc was only occasionally split at 366x. Nevertheless, the stars looked crisp at the ultra low power used to monitor the asteroid occultation. I observed the asteroid 54 minutes after the event, when it had moved 18” away from the target star, and the asteroid was barely visible with direct vision at 366x. So the asteroid was as faint as it should be. The asteroid could not have been seen with the ultra low power of only 45x used during the occultation. Therefore the object which was at least magnitude 12.9 during the asteroid occultation must have been a companion star.”
Tony showed the light curves of the published occultation events showing the step events in brightness. Tony reminded everyone to carefully analyze their light curves for anything that might look like anything other than a perfect drop in brightness as this may need further analysis.
Two more reports are in progress (not published):
3UC197-115375 occulted by 336 Lacadiera on 2009 April 16
TYC 2322-01054 occulted by 695 Bella on 2010 August 31
The 336 Lacadiera event light curve indicates a fourth component of a previously known triple star system, making it a quadruple star system. This is an example of an event with very unequal star magnitudes. This report is still in progress. The 695 Bella event light curve found a component so close to the primary star that the secondary occultation was barely detectable. This is an example of an event with very unequal star magnitudes. This report is also still in progress.
Paul Maley reported on the 2011 April 1, 554 Peraga Occultation Expedition to Iraq 3/20/11-4/2/11. This was the 1st ever successful recorded asteroid occultation from Iraq. He arrived in Erbil, Iraq and worked with amateur astronomers of Kurdistan. Paul showed a few slides of the living conditions and interesting sites in the area including the Korek Observatory which houses a radio telescope plus 1.5 and 3.5 meter optical telescopes. The domes housing these telescopes were attacked and had huge holes in them. The government removed the telescope mirrors and they were relocated and able to be saved.
Paul located an observing site in the town of Shaqlawa in the mountains. One of the local amateur astronomers brought a donated 6-inch refractor. Another scope used was a donated 8-inch Meade LX-200 that Paul used. The observers on this event assisting Paul were Azhy Hasan and Rojgar Hamid. They successfully recorded a 5-second occultation D = 18:53:14.5UT, R = 18:53:19.5UT. Three other chords were obtained in Europe. Richard Nugent analyzed Paul’s data and created a YouTube video for the Iraqi participants. It is located here:
Walt Morgan presented to David Dunham and Dr. Eberhard Bredner the first IOTA-VTI GPS timing units just recently manufactured. This new unit fills the gap and replaces the discontinued KIWI unit. The web site for more information and ordering is http://www.videotimers.com/. Walt gave a demo of the 12V powered device which has a built in GPS receiver thus it’s a single box unit.
Walt told about the history of timing accuracy and how the IOTA-VTI came to be. It was designed by Tony Barry and Dave Gault, active members of the Western Sydney Amateur Astronomy Group (WSAAG), in Australia Earlier this year Tony and Dave assigned their rights in IOTA-VTI to IOTA, the intent being to allow IOTA to assure its members of the continuing availability of a precision video time insertion device. Toward that end, IOTA subsequently granted a license to Video Timers to manufacture and market IOTA-VTI. One condition of the license is that IOTA is to receive a royalty for each unit sold.
The engineer for
Video Timers is Sandy Bumgarner, well-known to IOTA members for his work with
video systems, especially the manual gain modification of many PC164C cameras.
Walt (an active IOTA member for over 35 years, and IOTA Vice-president for
Occultation Services for a decade after the 1983 incorporation) has worked
closely with Sandy. Together they have transferred the excellent system created
by Tony and Dave to a rugged printed circuit board-based design. It's nice
The resulting device is well-matched to the demands of timing occultations: it is easy to use; it is rugged enough for field use; it produces legible characters in any lighting; its high-sensitivity GPS achieves accurate geographic fixes and it has been demonstrated to reliably produce accurate millisecond timing.
The first deliveries of the production version of IOTA-VTI were at the IOTA annual meeting. Anyone who chooses to buy one there will not incur shipping and handling charge, and, as a special offer, Video Timers will absorb the California sales tax. The total price for units delivered at the meeting will therefore be $249.
Steve Preston talked about star position issues as they affect asteroid occultation path predictions. The two main issues affecting star positions are proper motions and if the target is a double/multiple star. When a double star is suspected, the following sources are checked to see if the target might be a double: Washington Double Star Catalog (WDS), Interferometric Catalog and previous occultation records. If an orbital solution is not available for a known multiple star, then the path uncertainties would generally be invalid since path shifts may be much greater than the path statistics.
Proper Motions will be affected by multiple stars and their orbital motions. When Steve sees a large discrepancy, he’ll flag it and note it in the prediction. Older epoch observations carrying lower weights and the Hipparcos catalog with its short term baselines used for proper motion calculations can cause issues in the star positions and thus present errors in path predictions. Steve will do a full evaluation on duplicity and proper motion statistics if it is known that the asteroid event will be widely observed. Steve advises that if you see a notation about the star position in the prediction, be cautious and ask for more information before observing.
Brad Timerson summarized the database of 2011 asteroid occultations through June 30, 2011 in North America. Compared to previous year’s 6-month data, the total number of observations was down, but this is still only halfway through the year. Single chord observations make the most reports, but multiple chord observations are on the rise. Brad discussed 4 events that had inversion models (photoelectric analysis of light curves):
24 January 160 Una 6+ New Double Star
26 January 11 Parthenope 11+
19 February 7 Iris 6+
22 April 17 Thetis 4+
For the 160 Una event, David Dunham’s chord on Occult’s elliptical fit appeared to be off compared to the other chords. When the inversion model was overlaid on the fit, Dunham’s chord fit nearly perfectly with the light curve model of the asteroid’s shape. With the upcoming Antiope event on July 19 it was postulated on what the size/shape of this binary asteroid will show.
Hristo Pavlov presented his comprehensive occultation analysis program Tangra. He mentioned a few pros and cons compared to LiMovie, Tangra doesn’t support lunar events while LiMovie does. LiMovie reads only AVI formatted video files while Tangra reads nearly any video format. This feature alone of Tangra minimizes any loss of data in converting a video file to AVI format as LiMovie requires.
Hristo showed example light curves of the photometry methods (aperture and PSF) Tangra uses to analyze light curves. He then showed a demo of the program and it flexibility of uses and parameters in processing videos. Tangra has the feature of allowing integrating of frames which is similar to using a frame integrating/averaging camera such as the StellaCam. Another highly useful feature is built in brightness and contrast adjustments plus the use of custom filters to process data.
Tangra’s astrometry functions allow 0.2 pixel (0.3arc-sec) accuracy. Currently it can accept the following star catalogues: UCAC2, UCAC3 or NOMAD. The reduction process is simple. Take a video of a known field and identify at least 3 stars. Hristo demonstrated the astrometry function on a Near Earth Asteroid (NEA) and a comet. The program was recently used to provide accurate positions of Comet Hartley.
Dave Herald presented a summary of the best asteroid occultation events over the past 2 years. From 2008 on the total number of asteroid events has continued to grow with over 200 observed events in the years 2008-2010. In 2010 for example, Japan had 25 events, but the smallest land area and Australasia had smaller population with 50 events. The US had 106 events and Europe had 51 events for 2010.
Double star discoveries result in ranges of separations of 0.1" – 0.001" with uncertainties in the range of 1-3 mas. In the past 2 months nine double stars have been discovered.
Dave showed profiles of several of the successful events starting with 234 Barbara over Florida and Europe in Nov. 2009. 472 Roma occulted δ Oph (m = +2.7) on July 8, 2010 over northern Europe and had 222 observers, ( 26 produced chords, 27 observations not used and 142 misses). Due to the large asteroid and small star size issue, light curves showed more gradual D’s and R’s producing a non-consistent size/shape result. Other profiles showed:
790 Pretoria Jul 19, 2009
449 Hamburga Sep 9, 2009
216 Kleopatra Dec 24, 2009 (cigar shaped asteroid)
81 Terpischore Dec 25, 2009
80 Sappho Jun 4, 2010
16 Psyche Aug 21, 2010 (had a timing issue with one chord)
695 Bella Aug 31, 2010
96 Aegle Oct 29, 2010
93 Minerva Dec 24, 2010
212 Medea Jun 8, 2011
160 Una Jan 24, 2011
11 Parthenope Jun 26, 2011
Dave then presented results of a comparison of asteroid occultations and their light curve inversion models from a paper published in Icarus this year. The co-authors of the paper were:
Josef Durech, Mikko Kaasalainen, David Herald, David Dunham, Brad Timerson, Josef Hanus, Eric Frappa, John Talbot, Tsutomu Hayamizu, Brian D. Warner, Frederick Pilcher, Adrian Galad.
GPS millisecond timing of asteroid occultations provides the highest resolution of the object’s profile down to about 1-km with the exception of space probe encounters. This however is the projected profile toward Earth at the time of the occultation (snap-shot). An issue with occultations is the slight rotation of the asteroid as it shadow crosses one side of the Earth to the other. With careful analysis of light curves over several complete phases of their rotation (which can take years), 3D inversion models of the asteroid can be generated. An important consideration in deriving these models is the magnitude variation which depends on the axis facing Earth which can be 0.15 magnitudes and larger. Inversion models can derive a shape of an asteroid, but not it size.
Occultation profiles can be with combined with inversion models. If the 3D model is generated for the orientation at the time of an occultation, it can be matched to check on the accuracy of the inversion model.
Dave showed comparison overlays of occultation and inversion models on the some recent occultations: 515 Amherstia (2011 Apr 18) and 135 Hertha (2008 Dec 11). The 135 Hertha comparison is shown below (colored lines-from occultation):
The Parthenope comparison had matching issues at the 10 o’clock and 2 o’clock positions (chords 10, 12-14, 17):
Other inversion models/occultation comparisons shown were:
3 Juno 1979 Dec 11
5 Astraea 2008 Jun 6
17 Thetis 2007 Apr 21
88 Thisbe 1981 Oct 7 and 2007 Feb 21
372 Palma 2007 Jan 26 and 2009 Sep 10
925 Alphonsina 2003 Dec 15 and 2003 Dec 22
From EVO, Dave Gault asked “Has there been a case where an inversion model and an occultation model exist of an asteroid that has been visited by a space craft?”
Dave Herald replied “Not to the best of my knowledge.” Dave then demonstrated how to put the cursor on an inversion model and drag it to any orientation.
6PM Meeting adjourned – exactly on schedule !!
9:05AM Sunday July 17- Technical Sessions continue
David Dunham talked about the history of multi-station deployments. In the 1990’s he realized that the equipment is doing all the work, and maybe he should be somewhere else making an additional observation. On November 12, 1998 for the graze of Omicron Leonis, he set up a 5-inch clock driven telescope at Delta, Pennsylvania and left a student there to adjust it. He then set up another telescope 0.5 km away to record the event. When he came back, he was excited to see the system recorded multiple occultations of the star. He asked the student, “Did you make any adjustments?” The student replied “No”. David said, “At least, you were there to protect the equipment”. The student responded, “Actually, it was the other way around. Whenever a car drove by, I hid behind the telescope box.”
This experience led him to try another event. On 1998 Nov. 26, after Thanksgiving dinner, he drove about 10 miles south of home and set up an 8-inch SCT with video to record a marginal grazing occultation. Then he set up another telescope 200 meters north and observed the graze visually there. The video station recorded three events, the first unattended mobile video occultation observation, as far as he knew. Two nights later, he had another success with a better graze, of 4th-mag. c Piscium at Assateague Island, Maryland.
For asteroid events a much longer time for planning is needed. In prepoint planning, RA difference times need to compensate for the 10-second difference between sidereal and solar rate. David’s first successful attempt for an asteroid occultation was the occultation of 6.0 mag SAO 78349 by 9 Metis on September 7, 2001 in the Sacramento Valley. He set up a remote station in Orland, CA and drove some 20 miles to set up a 2nd manned station. When he returned to the remote station, the camcorder battery had died, luckily after the occultation !! The profile was published in Sky and Telescope for March 2002.
David then showed a list of 26 successful remote observations from Sep 2001 through Feb 2008. During the time period 2002-2008, Dr. Roger Venable led the way in the development of multi-station deployments and authored Chapter 10 of the IOTA Manual on this topic. One clever idea Roger used was to program a VCR to start recording near to the time of the occultation to save on tape and power requirements.
In 2008, Scotty Degenhardt came on board and turned the occultation community upside down with his army of Mighty Mini remote video stations. After several failures, Scotty’s first successful multi-station event was 135 Hertha on December 11, 2008. He had an unprecedented 14 successful hits from 14 remote video stations !! Scotty’s Mighty Minis can reach mag. 9.5 and even 10.0 under ideal conditions. Scotty’s arsenal also includes the Orion 80mm short tube refractor reaching m=11.0, and the “Mighty-Maxi” and the Orion 120mm short tube refractor, reaching m=12.0. To simplify the start of recordings, Scotty now uses programmable remotes to start them.
David showed slides of his multi-station efforts to record the m = +2.7 star by 472 Roma on July 8, 2010 where he had 4 stations. Others included: 16 Psyche on August 21, 2010, where he had acquired 5 chords, 695 Bella on August 31, 2010, with 8 chords and 2 misses, (Paul Maley had 2 chords).
The Bella all nighter success was extremely exhausting for David. He developed an ear infection as his plane landed home in Maryland, then the flu. After 2 weeks he went to a Doctor. He had thyroiditis and his recovery took 6 weeks; he wasn’t back to 100% for a few months. Multi-station deployments is an extreme sport, and IOTA needs younger folks to help out!!
Bruce Holenstein and Russ Genet updated IOTA on the Alt-Az Initiative project. This is a major undertaking in designing and building an affordable 1-meter class portable telescope. This telescope is expected to cost about the same as a C-14, have a 30 minute setup time and reach 2.5 magnitudes fainter than a 14-inch aperture. This would allow occultation targets not previously reachable, such as TNO’s, KBO’s, Pluto occultations, etc. Needless to say, deep-sky enthusiasts are also very excited about this project.
Russ Co-chaired the Light Bucket Astronomy Conference Dec 31, 2010-Jan 2, 2011 in Hawaii and gathered ideas from touring the large Gemini and Canada-France Hawaii Telescopes. A prototype of the 1-meter telescope was used at the Riverside Telescope Makers Conference (RTMC) astronomy Expo May 28/29, 2011 at Big Bear, CA
They are currently working on the design of a 1.5-meter portable telescope. It will weigh less than 400 pounds (880 kg), and be transportable on any road with a trailer.
The design and building of such a large portable telescope will require new technologies. Russ has applied for grant money to facilitate the continuation of this project.
Bruce took over the presentation and discussed new technologies needed. This included the mirror fabrication process to produce a strong lightweight mirror, non-vacuum coatings and mounts to make these telescopes ultra portable.
The group is also investigating various fast cameras for occultations, spectroscopy, astrometry and other uses. Frame rates of cameras being evaluated range from 30 fps to several hundred fps.
In addition active primary/secondary mirrors are being investigated for utilizing adaptive optics technologies. One such method is uses of electrostatic charges to create deformations on the mirrors.
Bruce indicated one of his main interests in this project is using high frame rate cameras on stars for occultations. This is to measure scintillation effects and determine stellar diameters. Scotty then told the group that Richard Berry has come up with a method to do high precision astrometry on an 8-inch telescope with a fast fame rate CCD camera when the star and asteroid are on the same frame. A variation of this method was used in the 1990’s called “last minute CCD astrometry”. With a meter-size telescope and a fast frame rate camera, high precision astrometry is of special interest to occultation observers to modify path predictions.
The Alt-Az website is http://www.AltAzInitiative.org and the discussion group is - http://groups.yahoo.com/group/AltAzInitiative
David Dunham next showed a summary of remaining occultation events for 2011. These are from the 2011 RASC Observer’s Handbook. One missed event not in the handbook is the occultation of a m = +5.1 star, HIP 16322 (4 Tau) by 1693 Hertzsprung over south Florida. David also showed a list of remaining grazes for 2011 also straight from the Handbook.
David then showed major events from the Observer’s Handbook tables he’s now compiling for 2012. The best asteroid event is of the m = +2.7 star HIP 72622 by 363 Padua on September 16. The event is in daylight over the US but occurs in darkness over Africa. David referred to Steve Preston’s page listing “Best Worldwide Events for 2012”.
Paul Maley talked about a proposed expedition for the 363 Padua asteroid event on September 16, 2012. This 2.7 mag star is the brightest event for 2012. Most of the path is in daylight over the US, the best viewing is in West Africa. The duration is short, 2.1 seconds with a 12.1 magnitude drop. Possible concerns is that the star might be a double/spectroscopic binary. The low elevation of 22 deg will make it difficult plus the event occurs just 1 hour after sunset.
The event is in daylight over south Florida (Tampa and West Palm area) where IOTA observers Tom Campbell and Terry Redding live. The path also goes over Washington State where other IOTA observers are located. The solar elongation is about 51 degrees. Tom Campbell said he would continue to experiment with an IR bandpass filter with an 8-inch telescope. Paul mentioned that he already used the device and failed to see a comparable star at that solar elongation.
Paul is planning an expedition that would have a maximum of 8 persons mainly due to safety and transportation limitations. Paul has the details on his website: http://www.eclipsetours.com/padua.html
David Dunham reported on the grazing occultation expedition of Eta Gem (m=+3.7) to central Arizona about 50 miles west of Phoenix on 2011 April 10. For this graze the attended (human ) stations failed while the remote video stations all worked! David showed Google maps of the locations of the 5 stations. This graze had the typical problems: strong rainstorms earlier that day, jammed tapes in camcorders, etc. The end tally was Machines: 3, Humans: 0. David has an article on this expedition in JOA Vol 1 No. 3, page 9.
--Lunch Break 12:50PM—
1 PM Technical Session Continues
David Dunham shared a few videos: An asteroid occultation from one of his Mighty Minis, and the Eta Gem Graze from April 2011 including a spectacular step event due to the star’s giant size. David showed the most recent issue of JOA mentioning Kazuhisha Miyashita’s article on “Measurement Region of LiMovie for Occultation by Earth-Lit Lunar Limb”.
Dr. Eberherd Bredner is the IOTA European Section Secretary and came all the way from Germany. He said a few words about his occultation experiences with the IOTA ES. He brought and presented the ESOP (European Section on Occultation Projects) conference poster and stickers, and invited attendees to Berlin next month August 26-31st for the meeting. Eberhard said that he was glad to be with us at the IOTA meeting and able to try to observe the Antiope occultation.
He also was interested in recruiting more observers. Eberhard suggested a good way was to get new observers to perform total and grazing occultations. Even with the Kaguya data, one's own observations can be compared against the high precision Kaguya data.
Dave Kenyon showed a few things the Astronomy Dept is doing at Sierra College. They have an all sky camera (part of a network over northern California/Nevada) that does frame comparisons every 0.03 sec. This camera system was designed for meteors and other transient events but it also picks up birds, planes and other false objects. Typically the cameras pick up a few real events per month. A recent event was captured and Dave had used software he wrote to determine the true triangulated position of the object as projected on Earth.
Francois Colas briefly presented his research on TNO occultations. Unfortunately at the meeting his computer died and his powerpoint file wasn’t available.
Dave Gault and Tony Barry presented their talk on the new IOTA-VTI as given at the 5th Trans-Tasman Symposium on Occultations 2011 May 26-27. Dave and Barry developed the IOTA-VTI and licensing to avoid availability gaps for a VTI for occultation work. From their website:
“IOTA-VTI is a rugged, reliable, ready-to-go unit, deriving precision time from an internal GPS receiver. The ABS enclosure is about five inches square and two inches high.
IOTA-VTI is compatible with both NTSC (30 frames/second) and PAL (25 frames/ second) video formats. Selection of format is via an internal switch that will be set to the buyer's preference, but which can be easily changed.
IOTA-VTI has been tested extensively, both on a bench and in the field, so we are confident it will meet your need for precision timing of video signals.”
The IOTA-VTI features include:
Will work without a camera connected
LED to confirm that a camera is connected.
Internal built in sensitive GPS
Characters have a drop-shadow style – viewable against say, the lunar bright limb
Comprehensive Data Quality Assurance system
GPS Almanac Management System
Licensed to IOTA to prevent untimely withdrawal
Price US $249 + shipping
Can be ordered now
The time frame from prototype to demo unit was 8 months. Initial quality assurance tests compared to the older KIWI connected to a PC with Garmin 18x LVC GPS demonstrated timestamp accuracy consistent with these devices. Dave showed shots of the Position screen, Time screen, Full screen and TV safe modes.
The unit also has a dedicated screen for GPS Almanac Management System (GPS-AMS) showing diagnostics and information regarding satellites and degree of precision as shown below:
The unit also performs constant Data Quality Assurance (DQA):
-The IOTA-VTI samples the serial data and the 1pps from the GPS every second
-5 tests every second + 1 test sequentially over an hour
-Overall policy is to ‘squawk’ loudly on error
-Reports on status of satellite fix
The units are available now and be purchased directly from the website: http://www.videotimers.com
Unit size is about 2 x 5 inches:
Dave says the almanac takes 10-15 minutes to create from a fresh start. He suggested running a connection outside your car window while driving to the occultation site, and switch to video cables upon arrival.
Tony asked if units could be sent to
Iran/Iraq. United States Law in general is that technology and
supplies, parts or services may not be exported, re-exported, sold or supplied,
directly or indirectly, from the United States or by a U.S. person, wherever
located, to Iran or the Government of Iran. This includes U.S. goods,
technology, parts and or services that a person knows that the end user will be
in Iran or the Government of Iran, even if the product is initially sent to a
country other than Iran.
To whom do these sanctions regulations apply? All U.S. persons and entities (companies, non-profit groups, government agencies, etc.) wherever located.
It was cautioned that IOTA should not be involved in any manner of technology transfer to Iran even from another country as it could be traced back to the organization and create serious problems.
Bruce Berger, working with John Broughton and David Dunham presented the design and specifications of the “Ultra-Portable Telescope for Occultation Expeditions” i.e., suitcase telescope.
This design allows the suitcase telescope to be transportable via road and aircraft and uses a new alt-azimuth mount design. The design requirements called for the telescope to be inexpensive, lightweight, compact, has a ground hugging profile, and a minimum FOV of least 20 arc-minutes. Currently the telescope has a 10” f/4 aperture with a 50mm finder.
The design looks like this:
and disassembled fits in a suitcase:
Pointing the telescope is accomplished with a video finder incorporating a camera lens. The FOV of the telescope with a Watec 120N camera is 23.6 arc-min. John uses a mini DVR to identify stars from a prepoint chart. John showed video frames of the occultation of 194 Prokne from 2011 May 13. The telescope recorded a high quality 17.82 sec occultation. John shipped the telescope to Bruce in Boston for additional use/testing.
Bruce knows someone in his area that knows about fabrication. The plan is to have this person’s students come up with a possible mass production design for manufacture.
David Dunham had borrowed the telescope setup for the meeting for the attendees to see:
Walt Morgan showed a live demonstration of the IOTA-VTI with a camcorder pointed at the wall with output to personal DVD recorder/player:
Being indoors, the 4 satellites needed for accurate time were not acquired. This condition is noted by the hourglass on the top image above-left of the 23:08:03 time.
Walt showed some screen shots of the IOTA-VTI unit in action from the website and explained the meaning of each line of text. Three satellites only provides a two-dimensional fix and four satellites provides the desired three-dimensional fix. Six types of errors are possible with the unit. Users are referred to the on-line manual for explanation and solution of these error codes.
In the Spring 2011, prototype #4 of the unit was sent by Dave Gault to Gerhard Dangl in Austria. Gerhard ran his Exposure Time Analyzer. The results were consistent and times produced by the new unit were deemed accurate.
Antiope update: Dunham and Preston discussed weather updates for the 90 Antiope occultation for the following night.
Bill Merline from the Southwest Research Institute provided an astrometry update for the components of 90 Antiope for the occultation. He was at Keck in Hawaii the previous week and checked for duplicity of the target star (there was none detected). The FOV was too small with the Keck telescopes for an astrometric position since there are no reference stars visible. Bill showed the Keck images of the two asteroid components as they should appear 30 minutes away from the predicted orientation:
The July 19 prediction from the French team was PA ~ 26 deg, Sep ~ 168 KM, Current Keck observations predict PA ~ 21 deg, Sep ~ 145 km. Separations are center to center between the two components.
Bill briefly addressed IOTA funding possibilities an that they are still in the process of attempting to define targets of interest. this process is expected to take additional months. The large Keck telescopes with adaptive optics can’t measure the sizes of asteroid satellites because they are so small. Asteroidal satellite positions can be predicted which can be used by IOTA for positioning of telescopes to catch these occultations.
The meeting unofficially adjourned at 5:30PM and the group talked about station plans for the Antiope occultation, weather updates and continued their discussions.
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.