The International Occultation Timing Association's 34th Annual Meeting

Oklahoma State University

  Stillwater, Oklahoma

July 29-31, 2016

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Jean Meeus -David Laird Award recipient

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Derek Breit - Homer Daboll recipient

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Joan Dunham shows IOTA VideoRecorder

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  Art Lucas and Byron Labadie

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Dr. Roger Venable  IOTA's Vice President

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Dr. David Dunham

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Art and Barbara Lucas, Paul Maley

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John Broughton's Paver mount

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Ted Blank

The minutes of all IOTA annual meetings are at:

http://www.poyntsource.com/Richard/IOTA_Annual_Meetings.htm

 

Derek Breit, 2016 Homer F. Daboll Award Recipient

                                                                                          

 

 

 

Jean Meeus - 2016 David E. Laird Award Recipient

                                                                              ----photo coming soon----

The 34th annual meeting of the International Occultation Timing Association was held Friday, Saturday and Sunday July 29-31 2016 at the University of Oklahoma , Stillwater Campus, Oklahoma. This location coincided with the spectacular crescent Moon graze of Aldebaran early in the morning July 29, 2015.

 The meeting location was kindly hosted by Art Lucas. The final meeting schedule, and most of the presentation files, are located on the IOTA web site presentation page:

                                                 http://occultations.org/community/meetingsconferences/na/2016-annual-meeting/   

Persons participating in the meeting in person and via internet conference:

On site attendees: President Steve Preston,  Vice President Dr. Roger Venable, Executive Secretary Richard Nugent, Ted Blank, Bob Sandy, Steve Conard, Paul Maley, Chuck Herold, Drs. David and Joan Dunham, Eric Benton, Byron Labadie, Don Stockbauer, John Grismore, Russ McCormick, Bill Hanna, Oliver Causey, Art and Barbara Lucas, Hal and Katie Povenmire.

Internet Conference Attendees:  Derek Breit, Brad Timerson, Ted Swift, Chad Ellington, Tony George, Steve Messner, David Herald, Aart Olsen, Bob Anderson, Gerhard Dangl, John Broughton, Bob Dunford, Denis Hopper, Wojciech Burzyriski, Bart Billard, Chris Douglas, Jerry Berdecker, Oliver Kloes, John Newman, Walt Morgan, Rob Robinson, Ernie Iverson.

1:00PM – Meeting start – Introductions

Vice President Dr. Roger Venable opened the meeting and welcomed everyone to the meeting. A brief summary of the early morning Aldebaran graze was talked about by the attendees.   

Business meeting:

Treasurer Chad Ellington (through Richard Nugent) presented IOTA’s membership status. Currently there are 28 USA   print subscribers plus 5 outside USA, 71 online subscribers, total subscribers is 104 with a net increase of 11 members since last year. Except for the member increase this year, membership trend is decreased in the past 10 years. It was mentioned that the IOTA list sever has over 700 members.

This trend 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:                   $9,608.45     2015, Oct 14

Ending Balance:                   $10,416.06   2016, Jul 21 (Includes funds donated for a

                                                                                   special asteroid satellite award) 

     Net Increase in Balance:        $807.61 

 

The breakdown of this past year’s budget is:

          Membership Income:          $600

          IOTA-VTI Royalties:         $496  down $192 from last year

          PayPal Balance:                  $1714.76

          Expenses:

              -Printing/Mailing JOA    consistent from last year              

              -Web Service:               Still Donated

              -Awards:                      $ Not paid for yet

The JOA it is getting further behind on schedule now 2 issues behind from 2015. More articles are needed. The new password access for downloading it is working, however many folks have trouble remembering passwords.

This year’s presentation of the annual Homer F. DaBoll award and David E. Laird award was made by the Award Committee Chair Ted Blank. 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. The David E. Laird award is given to people who have made significant contributions to occultation science prior to 15 years ago. Laird (1931-1968) was an organizer of grazing occultations in the early 1960’s. Laird confirmed the existence of a giant impact on the Lunar far side, The Laird award was conceived to help “catch up” on awards to some older IOTA members.

Previous Homer F. Daboll awardees: 2007: Dave Herald ( Australia ), 2008: Edwin Goffin (Europe), 2009: Steve Preston (USA), 2010: Hristo Pavlov ( Australia ), 2011: Scotty Degenhardt (USA), 2012: Kazuhisa Miyashita ( Japan ), 2013: Graham L. Blow ( New Zealand ). 2014: Brian Loader ( New Zealand ), 2015: Gerhard Langl ( Austria )

Previous David E. Laird awardees: 2013: Hal Povenmire ( Florida ), 2014: Gordon Taylor ( England ), 2015: Bob Sandy (Missouri)

This year’s Award Committee consisted of all past recipients (above), Ted Blank (Chairman-Massachusetts) Dr. Terry Redding ( Florida ) and Richard Nugent (Texas). This year 11 nominations were received – 8 for the Daboll award and 3 for the Laird award. The Committee’s main objective in selecting an award recipient was to reach a consensus and not choosing someone by a majority vote. Eligibility for the award is for anyone who has made significant contribution to occultation science or for the work of IOTA and its goals. Persons not eligible are current IOTA Officers & the award committee. Candidates nominated are not required to have IOTA membership.

Nominations were received from multiple countries and all nominees were excellent candidates. To gain more nominations a new web site will be available to all members to submit nominees all throughout the year.

This year a Special Achievement Award went to Art Lucas for his outstanding support for IOTA, arranging the 2005 and 2016 meetings plus his many observations of asteroid occultations.

The 2016 Homer F. DaBoll award recipient was Derek C. Breit. Derek has made numerous contributions to the occultation community with his numerous web pages and detailed maps for 1000’s of asteroid events, solar eclipses, etc. Derek is also a contributor to the RASC’s Observer’s Handbook, a regional coordinator since 2007 for lunar occultations, created the "Why Occultations Flyer" which has been passed out to all IOTA meetings/conventions.  He has participated in at least 20 grazing expeditions, 74 individual lunar occultations events and 53 asteroid occultations. His enthusiasm has been an inspiration to us all.      

Derek was notified of the award a few days before the meeting and sent a response for the Daboll award to Ted Blank. Ted read it at the meeting.

The 2016 David E. Laird went to Jean Meeus, for his 60+ years of sustained eclipse, occultation and positional astronomy calculations. Jean is a Belgian astronomer specializing in celestial mechanics. Jean was the first person ever to calculate a graze and observe it in 1959. His books are classics such as "Astronomical Formulae for Calculators",  "Astronomical Tables of the Sun and Moon.", Cannon of Solar eclipses (co-author), plus about a dozen othe books.

Executive Secretary Richard Nugent presented the IOTA’s election results. Officer elections are held every 3 years as per the by-laws. All current Officers agreed to continue and the election was announced on the IOTA list server with voting open from July 3-29, 2016. The voting was unanimous and the Officers re-elected are:

President: Steve Preston
Vice President: Roger Venable
Executive Secretary: Richard Nugent
Secretary & Treasurer: Chad Ellington
V.P. for Grazing Occultation Services: Mitsuru Soma
V.P. for Planetary Occultation Services: Brad Timerson
V.P. for Lunar Occultation Services: Walt "Rob" Robinson
Directors: David Dunham and Paul Maley

Roger Venable gave a brief eulogy for Sandy Bumgarner who passed away this year at age 75.  He was an active observer of occultations since the 1980's and always was full of energy when it came to occultations, electronics and IOTA activities. It was Sandy who designed and built the variable gain control ("Bumgarnering") for our occultation video cameras, an extremely useful feature.  Sandy also originally designed the IOTA-VTI which is the standard time recording method for all occultation observations.  As a child Sandy lived on Mt. Hamilton and his parents worked at Lick Observatory. He never finished high school but joined the Air Force and then went on to get a degree in electrical engineering. Sandy developed cancer in 2010 and opted for the aggressive treatment and lived 5 times longer then most medical personnel thought.

Art Lucas made a few comments about Sandy and how the Video Time inserter got started. Sandy and Art came up with a beam of light to practice focusing a telescope and this led to developments in adaptive optics. Sandy's website "poyntsource" (which is one of the IOTA websites maintained by Derek) came about from this idea.  

Ted Blank presented an update on the IOTA-VTI version 3. The VTI was originally designed by Sandy Bumgarner and sold and distributed by Walt Morgan under the name "Video Timers". 

The key features of the IOTA VTI version 3 are:

Powered by 8 to 28v DC (centre positive)

CCIR (PAL) or EIA (NTSC) compatible

Will work without a camera connected

LED to confirm that a camera is connected.

Internal sensitive GPS is standard

External GPS antenna available

Characters have a drop-shadow – viewable against say, the lunar bright limb

Comprehensive Data Quality Assurance system

Lithium battery give the unit a non-volatile memory

Licensed to IOTA to prevent untimely withdrawal

Price  US$249 + shipping

Can be purchased now at http://www.videotimers.com

The units were modified by Dave Gault and Tony Barry of Australia. IOTA has exclusive rights to the units. Currently Walt is the manufacturer. Each quarter, Walt send the royalties from the sales is sent to Chad Ellington, IOTA's treasurer.  

Since 2011 when the unit was introduced over 400 units have been sold. Most all of the units have been bought by IOTA and "occultationists", including Marc Buie's RECON team. It was mentioned this this year Walt would like to transfer the VTI manufacturing and sales to someone else. For attendees at this IOTA meeting, units were available for purchase at a discounted price of $200 (normally $249).

       Technical Sessions

Steve Conard presented early data from hardware tests  - ONAG system. This is a high speed data collection system. He used a ZWO 224 color camera in the near infrared. He showed the results using Aldebaran occultation from January 2016 at his observatory in Maryland. Frame rates can be as high as 550 fps windowed in a 10-bit mode; he utilized a 280 fps rate for the Aldebaran event with his Celestron 14 and Stellacam EX camera. Steve showed 2 videos of the Aldebaran occultation - 30fps StellaCam and the 220 fps ONAG system.  The StellaCam showed a few frames for the "D" and the high speed system also showed a rapid drop in brightness with a larger number of frames forming a smooth arc at the bottom of the light curve.           

Steve Conard next presented test results from several Mini DVR video recorders. The Canon ZR video recorders have been popular choices for occultation observers, however they are no longer made and have lots of problems as they have been aging. The smaller DVRs are mainly used by motorcycle riders, dirt bike racers, and the included button cameras can be used for surveillance video.  

He bought some low cost  DVR's. The cost depends if you buy them directly from the Chinese manufacturers or a USA Seller.  They have 2.5" screens, many skip every other field at 30 Hz, and the batteries last a long time. They do not however have a programmable start timer which would be EXTREMELY useful for remote stations for asteroid events. A "Readymade RC RMRC Pro-1200 Steve acquired has a 5" screen, can also record wireless video and records in high resolution color. Cost: $150.  Steve showed a comparison chart  of the 4 units he tested.

Steve found a method to make programmable start time recordings using some of the unit's "automobile mode" with a low cost delayed timer from ebay. Steve also estimated the approximate S/N ratio and found that recording to a laptop directly vs. to the DVR, about 0.5-1  magnitude was lost in brightness with the DVRs. Steve's overall comments was that the units make a good backup, they have nice features and are compact.

 Steve Conard next presented a new EXTA (Exposure Time Analyzer) invented by Gerhard Dangl and built by Bob Auburger from design instructions from kuriwobservatory.com. The system allows for finding a timing errors in our video cameras. The primary driver for fabricating this device was to determine time accuracy of the less typical cameras used for specialized observations.  He showed videos of test results for the StellaCam at various integrations. The unit can analyze at 2 millisecond intervals. Near term plans include testing of ZWO 224 cameras, and Joan Dunham's ZWO and QHY cameras.  The unit is available for loan to any USA IOTA member and the member must pay for shipping cost both ways.  

Atila Poro from IOTA-Middle East (ME) presented their experiences and goals via a pre-recorded You Tube video. IOTA-ME got started 6 years ago in 2010 and has had over 70 active members, more than any other IOTA region. IOTA-ME has participated in many conferences, members have observed over 300 lunar occultations, 4 successful asteroid occultations, several members are working with professionals on NEAR objects plus members have been doing research on binary stars and exo-planets. Atila has been recruiting and teaching younger people occultations to foster more interest. The average age of their members is 24, and he has even done outreach to high school level students.           

Bob Anderson presented ArtStar/ArtStar Lite: a new testing system for video cameras used in occultations. It's a system that runs on a laptop for testing cameras and frame grabbers. Bob showed the hardware components and some tests using a Watec 120N integrating camera. A nice feature of ArtStar is the ability to show an occultation in a frame by frame mode.  ArtStar Lite uses small PVC parts compared to the longer optical tube for the ArtStar system. The few kinks/surprises he found in his analysis affect the photometry of the recordings, not the timing.  

Bill Hanna presented his ambitious idea for autonomous observatory stations - a development in progress. There is no doubt - setting up multiple video stations has many issues to deal with and the procedure is complicated. Bill is investigating a self contained unit with an easy fast alignment plus the unit would operate automatically from there. Initially there would be a manual coarse alignment, using the Sun, Moon, bright star or for daytime alignments - a terrestrial target such a tower or mountain peak. The units would have a "on board" computer for comparison alignment. Fine alignment would involve pan/tilt mirror control, (x,y) mirror control and possibly tripod leg servos to change the lengths. Using a mirror mounted just above the objective of a telescope, to Bill was able to get within 16 arc-minutes on multiple slews using widely available servo motors.  He hopes to use digital servos on the next round of tests. They have drawbacks: they use more power, have possible overheating issues and are more expensive.   One suggestion was to point the telescope down on a ground mounted mirror that moves to orient the FOV. As a example, the 10-meter Hobby-Eberly (Ft. Davis , Texas) telescope's primary is fixed. The secondary mirror moves around and the telescope is able to cover 70% of the sky.

Paul Maley and Tony George presented their  observational results of a 13th magnitude star occulted close (3 degrees) to the full Moon. The  m = +13.2 star and m = +12.7 asteroid 712 Boliviana would result in a Δm= 0.5. A seemingly impossible observation, Paul tried it anyway. He used a Celestron 11 and a Watec 120N integrating camera at his place in the Phoenix area. With the star so close to the full Moon, he began setup 1.5 hours before with pre-point charts provided by Ernie Iverson. To bring out the stars, Tony used Registax to stack frames. Unfortunately a pointing error resulted in Paul recording the wrong field. However Paul did get the Pallas event on July 7, 2016 with a 0.8 mag drop and Tony was able to bring out the occultation.           

Richard Nugent presented an analysis of an unusual 1960 occultation made by a father and son in Indiana. Leo Deming published a letter to the Editor in the February 1961 Sky and Telescope magazine about an unusual lunar occultation he and his son observed on November 25-26, 1960. Both father and son observed the star ZC 3333 disappear, re-appear and disappear by the 60% illuminated Moon. Deming thought the Moon’s oblique motion relative to the star caused this effect (possible grazing occultation). Nugent remarked that in 1960 grazing occultations were virtually unheard of and most amateur observers didn’t have the instant access to the databases and software we have today. Nugent analyzed the event with OCCULT and LOW (Lunar Occultation Workbench) software and found that it was not a graze but rather a total occultation of a close double star. The separation of the components was 2.4″ and the Kaguya lunar profile and the Moon’s motion explained the observations.

 5:30 PM - Adjurn

 - -9:00 AM Saturday, Technical Sessions continue - -

After some technical problems getting logged on  Dave Herald presented the impact of GAIA on asteroid occultations.  A number to remember is that 1 mas uncertainty for main belt asteroids corresponds to about 2km on the Earth's surface. Right now, typical star position uncertainties = 50 mas, and for asteroids 150 mas. Path shift errors are the result of both uncertainties. GAIA is expected to produce positions to m-arcsec (0.000001", one thousand times better than the Tycho-2 positions), proper motions and parallaxes of  1 billion stars to m = +20.  Asteroid positions will not be released until 2019, thus realistically assuming the star position is known, all uncertainty will be with the asteroid position. With accurate asteroid positions known to the expected certainty, path predictions should be accurate to within a few km vs. the dozens of km they are now. This will be a tremendous  advantage to recruit new and old observers who have though of the chasing asteroids was a wasted effort.

GAIA will impact variable stars - photometry will be done on 5,000,000 classic Cepheids, 3,000,000 eclipsing binaries, 300,000 binaries with rotationally induced variability, 250,000 Miras and SR variables, 60,000 - 240,000 delta Scuti variables, 70,000 RR Lyrae variables and 20,000 supernova. Compare this to the AAVSo index catalogue of 342,000 variables !!

GAIA will also impact double stars. Expected data are 700,000 radial velocity orbits, 800,000 radial velocity and astrometric orbits, 2,000,000 astrometric orbits, 4,000,000 non linear proper motion systems, 40,000,000 resolved binaries.  All binaries could be resolved with separations less than 20 mas. Compare this to he current Washington Double Star Catalog: 135,000 doubles, and the USNO 6th Astrometric Catalogue: 83,000 pairs. ( WOW !!)

Dave Herald presented how to report light curves with Occult.  Dave has uploaded over 2,060 light curves to the VizieR database.  Why do this ?  At video recording rates of 30 fps, an angular resolution of 0.01" can be obtained. Light curves contain important information of occultation reductions and having them available can assist current and future investigators. Light curves can show the presence of a double star either by discovering or confirming them. Dave showed how to use Occult to report light curves. Tangra has this capability to transfer light curves to Occult, Limovie now has it.  Light curves can also be viewed in Occult.

Brad Timerson presented his yearly asteroid events statistics since the 2015 meeting.  For 695 Bella, light curve analysis showed a new double star. Brad showed individual events and their excellent agreement to inversion models, including an observation in January 2016 by Ned Smith which was originally thought to be an asteroid moon observation, but following detailed analysis it turned out to be a graze of the asteroid.

Dr. David Dunham  presented the best observed lunar grazing events he made recently including the Aldebaran graze coinciding with this meeting. He and wife Joan set up 7 stations, in which 2 of them they attended. He made most of his observations on the very sturdy John Broughton paver mounts.

David Dunham showed how to use last minute weather forecasts for mobile station positioning. For long range cloud cover forecast he uses weather.gov and watch the cloud probabilities. He also uses "Skippy Sky", the Canadian Weather forecasts for astronomy, Weatherbell (pricey at $25/month), the European weather site ECMWF and Meteoblue. Its always a guess when trying to predict cloud cover more than 1- 2 days out.

Bob Anderson talked about Correlated Noise as a factor in error estimates of timings. He discussed correlated noise, temporal noise and the various characteristics of each. He set up various Monte Carlo simulations: ordinary least squares, weighted least squares, log likely hood and a correlated log solver.  His analysis of noise will impact light curve reductions.

Tony George presented an update for R-OTE v4.5.1. (R-code Occultation Timing Extractor). R-OTE runs on a variety of platforms, Windows 7 - 10, Safari (Mac), Google Chrome, Internet Explorer, etc. R-OTE identifies the concept of noise asymmetry in light curves between event noise and baseline noise. It uses the Akaike information Criteria (AIC) to determine whether an event really occurred or if it was result of noise fluctuations and other random effects. It can also allow analysis of gradual transitions of larger stars and stellar limb darkening.

   - 12:15 Lunch Break -

Ted Blank next talked about a comparison of three video time inserters. Terry Redding, Ted Blank and Walt Morgan compared 3 different VTI's each with outdated almanacs. The Time inserters compared were the Kiwi ODS, IOTA-VTI and IOTA-VTI v3. Paul Maley asked if needs to run his Kiwi VTI for at least 30 minutes prior to recording times. Bob Sandy said Walt Morgan says it needs to run at least 20 minutes to update the almanac. (This issue was posted to the IOTA discussion group and it was noted that 2.5 minutes is the minimum time needed and 12.5 minutes is the likely maximum time needed to update the almanac and have accurate times).  All units were started and Ted showed screen shots of their almanac download progress (screen shots). At 4min 6sec elapsed time all units were reporting time, but all the times were different in integer seconds. All 3 units were in agreement with the time display at elapsed 7min 37sec.   

David and Joan Dunham talked about their previous night's pre-pointing using John Broughton's paver mount for the Aldebaran graze. The paver mounts are alt/az mounts attached to a patio paver stone. The paver stones sit on the ground are heavy and are not subject to movement from wind and other atmospheric effects. David brought his telescope setup with Broughton's paver mount that attaches to the patio stones and demonstrated how it's setup and works.

Steve Preston talked about using star catalog comparisons with thoughts about GAIA data. Its well known that different catalogues have different reference frames (different telescopes used to photograph fields, different/combined catalogs used to reduce the data, etc.) In comparing catalogues, UCAC becomes unreliable for stars brighter than m = +8, URAT1 proper motions are generally not reliable. Normally Steve will combine the UCAC4 proper motion with the URAT1 mean position to derive a star position for an occultation. As mentioned earlier by Dave Herald, GAIA will help in the short term with relative astrometry as "last minute astrometry" won't be needed. Only the asteroid position will be needed to be updated as the GAIA star position will be excellent. As GAIA improves asteroid positions, the orbits will be greatly improved and thus the path predictions will also improve.   

David Dunham talked about 4 bright asteroid occultations to occur within a month of this meeting.  They are:

71 Niobe - Aug 15 2016 - north south path Canada to Austin , Texas, m = +10.8 star

85 Io - Aug 26/27 2016 m = +7.5 star SAO 126327, Michigan to Texas, 208km path

51 Nemausa  - Sep 3, 2016, m = +7.6 star, N. Dakotas to Arizona/New Mexico

224 Oceana - Sep 8, 2016, m = +6.9 star HIP 86404, Baja California to New Mexico

David Dunham next presented Regulus occultations he attempted. David showed slides of Regulus occultations beginning with the 2005 event over Europe where chords were obtained. The widely advertised and anticipated March 2014 occultation over the NE USA was clouded out. This March 2014 event prompted Ted Blank to arrange in creating a cell phone app to time the occultation. The next Regulus event was May 24, 2015 of 1669 Dagmar in the Middle East where Paul Maley obtained a chord. Dunham traveled to Bengkulu near southwest Sumatra, where Regulus was followed to 6 deg altitude. The next Regulus event is October 13, 2016 by 260 Adorea in Papua New Guinea. The rest of the path is over the Pacific Ocean . 

 David Dunham showed the best grazing events for the coming year. The best one is Aldebaran on Oct 19, 2016, southern California (Los Angeles) to Ontario, Canada. The Moon's phase will be gibbous, 85% illuminated.  Next Aldebaran event is March 4/5, 2017, the path runs from  near Seattle to Toronto, Canada to Hartford, CT. The Moon will be 46% illuminated.  Next event is Aug 16, 2017, path is in St. Augustine, FL with Aldebaran just rising over the Atlantic. The next event is Regulus on Oct 15, 2017 - path is Oregon to New Brunswick with a 20% illuminated Moon. The last Aldebaran graze in the current series is Jul 18, 2018, NE Iowa to Ontario. The Moon will be just 11% illuminated and hence the altitude will be quite low. 

Roger Venable showed how he'll plan his summer vacation: plans for the Sep 1, 2016 annular eclipse in Tanzania in SE Africa . Roger showed slides of the limb darkening effect including the inversion/inflection point. A bailey's bead light curve he showed from the 2002 eclipse showed the bead light level dimming until the light curve became nearly horizontal, i.e. leveled off, but a non-zero brightness. The light remaining after the bead actually disappeared was the chromosphere, this is where the horizontal line began. The question is, where is the actual edge of the Sun?  Roger stated the Sun has an absorption spectrum and the chromosphere has an emission spectrum. Roger plans to observe this eclipse with the usual video cameras with a filter at 550 nm and a spectroscope to determine when the chromosphere appears. By timing when the chromosphere appears, he believes he can precisely find the inversion/inflection point and hence determine the actual edge of the Sun.  

Dunham talked about a half a year "down under", recorder timing tests, NACAA & TTSOO conferences. Dunham presented results of some asteroid events from 2015 he and Joan observed from Australia. They did the Lampetia occultation November 19, 2015, and 579 Sidonia, Dec 17, 2015. A graze was observed Feb 4, 2016 of SAO 106879 NE of Bridgton, Western Australia. For this event he had 2 remote and 2 attended stations.  Then came 344 Desiderata Feb 8, 2016. in which they ran 6 stations and obtained 6 chords, however the center 2 stations had timing problems.   On March 25-28, 2016 they attended the 50th NACCA and TTSO10 meeting.

Dunham  next presented his identical talk at the TTSO10 meeting on the Venus Ashen light from last October's occultation by the Moon. He briefly talked about the historical observations of the ashen light going back to 1643 by Giovanni Battista. He described attempts to observe the ashen light in the 20th century which all had inconclusive results. For the Oct 8, 2015 occultation, Dunham got a good video and it was analyzed by Tony George, Scotty Deganhardt and Roger Venable.  Dunham showed several frames enhanced of Venus reappearing from behind the dark side. A hint that some ashen light was detected was speculated by Scotty from his analysis. Tony George did a Limovie analysis of Dunham's video and it didn't corroborate Scotty's findings. Roger Venable's analysis  - he stacked images to eliminate Venus's movement. Roger's results were similar to Scotty's analysis. A paper is being prepared by the Dunham' on this event and analysis. The next Venus occultations are in 2019, 2022 and 2028.

- 6:20P Meeting adjourned and attendees went to dinner at a local restaurant-

9:00 AM Sunday – Technical sessions continue

Dave Herald talked about determining asteroid diameters and the role of occultations.  A recent New York Times article appeared a few months ago in which the author claimed asteroid diameters were significantly off due to inferior mathematical/statistical methods. Asteroid diameters are found from visiting satellites, radar imaging, direct imaging (adaptive optics) and occultations.  The occultation methods are relatively accurate (1km or better) however it is only a line of sight size/shape at the time of the event. And asteroids are irregular in shape - they are not all perfect basketballs. An issue is defining what the mean diameter is of an asteroid.

In principle, in fitting occultation chords to DAMIT and ISAM shape models, we can directly get the asteroid's mean diameter. Some problems are that shape models come from light curves and rotations which are not accurately known. Investigators deriving shape models generally never quote rotation uncertainties. So when fitting occultation chords, Dave added an option in Occult to use DAMIT and ISAM shape models (each one has multiple solutions) to rotate the shape model slightly to better match the occultation chords. He showed an example for 107 Camila. Adjusting the rotation for the shape model by a mere 1.7 seconds meant a good fit vs. a not so good fit to the occultations chords. Hence it very important that occultation  times be as accurate as possible. Historical occultations observations of Camila were also fitted to shape models and only the Sep 5 2004 occultation had any type of correlation. He derived mean diameters for Camila:

  223 +/- 4km, (equivalent volume), 

   227 +/- 4km (equivalent surface area)

 Dave Herald gave asteroid statistical results for 2014-1015. We are averaging 210 events/year. He gave the # of successful events by region for 2015:

Australasia - 44 events (16 sites for one event)

 Europe        61 events (50 sites       "          )

 Japan          25 events (17 sites       "          )

USA           88 events  (27 sites      "          )

Double stars - 5 discovered since Jan 2014.

He then showed several comparisons of shape models vs. occultation chords.

Dave Herald next talked about his record breaking graze from November 17, 2015. Previously the maximum number of events observed was in the low 20's. And many of these observations had issues of spurious events, so the real number is probably closer to 15 events.

With the LOR/LOLA lunar profile data, Occult can now predict the ideal locations to maximum the # of events an observer can observe/record.  Using Occults graze prediction, he set up 4.7 km away from the nominal graze path. For this event, the Dunham's joined Dave and the 3 of them were set up over 272 meters. Cirrus clouds hampered the 2nd half of Joan's observations, David didn't get set up in time and Dave was able to record the entire graze. Dave analyzed his video and came up with a record breaking 49 events !! Dave's record breaking video is on YouTube at:

                                                                                  https://www.youtube.com/watch?v=ucAP5FAx9uA 

Dr. Joan Dunham (co-authors Steve Conard, Steve Preston, Russ McCormick) presented Occultation Observations with the IOTA Video Recorder. IOTA VideoCapture 1.0 software was written by Russ McCormick. IOTA VideoCapture allows recording directly on laptops, thus its a computer based recording system. The Dunham's observed 107 Camila with this system. Joan listed the components needed for this setup, (see the 2016 presentation page for the Power Point talk for the list), the most expensive component was $99. The total cost for 2 systems  came to $560.  Steve Conard was able to purchase the system using ebay and Amazon for a reduced total cost of $115.  A drawback of the IOTA VideoRecorder is that it's a Window based system, currently there is no Apple/Mac version. Joan mentioned a few of the lessons learned with the system, a few are :  minimizing the number of external communications, keep the system awake (no sleep mode) and limit the # of USB ports used during an observation to avoid dropped frames.

David Dunham summaries of occultations by 216 Kleopatra. It has a large 1.4 mag light curve amplitude. He showed results and profiles of several occultations:

 October 10, 1980, (near the minimum of the light curve), a secondary occultation was recorded by Rattley and Cooke using photoelectric photometer some 440 km away.

 January 19, 1991 - showed the highly elongated shape - published in Sky and Telescope, later confirmed by radar observations

  August 10, 2003 - all visual observations from Mexico

 September 26, 2008 - observations by Dunham and Scotty using mighty minis.

 Dec 24, 2009 - Scotty had 8 positives from Arizona. This fit seemed to show a contact-binary model rather than a dog bone shape.

 2010 - adaptive optics images from the 10 meter Keck telescope  confirmed the dog bone shape and they discovered 2 satellites. After 30 years Rattley and Cooke's 1980 suspicious satellite was confirmed !

 March 12, 2015 - Over Europe, a large # of chords were obtained again confirming Kleopatra's dog bone shape. 

 April 5, 2016 - Dunham and Venable obtained 7 chords. 8 other chords/observers had misses. 

 David Dunham talked about the Aug 21, 2017 total eclipse and IOTA's planned effort. He showed the geometry of IOTA's method for determining the solar radius and why we need to be getting the maximum Bailey's beads near the eclipse limits. Historical observations of the eclipse from 1715 has been used in the some of the data analysis. The Picard satellite has completed its mission but some people (Sabitino Sofia) are suspicious of its diameter results.

David showed a chart of all he eclipses he analyzed (1715-2006) from a NASA grant. All relative diameter changes were made with respect to the 959.63" standard value at 1 A.U. The Feb 26,1998 eclipse over Curacao/Aruba had estimated radius correction of 0.04" to 0.22". This eclipse had 2 video recordings at both north and south limits. Video observers were Dunham, Dr. Patricia Rozenweig, Dr. Wayne Warren and Richard Nugent.

Another method to determine the instant of totality start/end is to record the flash spectrum as previously done by the Japanese. David suggested comparing the absorption vs. emission lines to effectuate this method.  He summarized the remaining work needed including re-analyzing the USA's 1806 and 1869 eclipses, using LRO data. At the March 9, 2016 eclipse in Sumatra, the Dunham's had to travel a bit south to get to partly cloudy sky and as a result they could not get to the edge. He then showed a few slides of the USA May 2012 annular eclipse effort to use narrow band filters and try and standardize the data acquisition. David showed how Boy Scouts and Con-Ed employees observed the Jan 24, 1925 eclipse over 1 block intervals on Manhattan island in New York City.  

A look at the path for the 2017 eclipse showed where the best weather prospects are likely  to occur. They are in eastern Oregon, Idaho and Nebraska. Another major issue is that no eclipse predictions allow for elevations (including Occult). And in Wyoming/Idaho observers could be at 3,000-6,000 ft !!  It was suggested that Dave Herald could modify Occult to account for elevations. He suggested coming up with a pamphlet to encourage people near the path edges to get involved and make history by making observations.

Just 2 days after the eclipse is a rank 78 asteroid occultation of a m  = +9.1 star path from Tucson thru Nebraska and the Great Lakes. However GAIA might make this a higher rank event after the 1st release of the catalog scheduled for this September 2016.

The meeting ended at 6:30 PM.

 

                                                                                                           

                                                                                                      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.