The International Occultation Timing Association  25th Annual Meeting at Columbia Basin College

Pasco, Washington

July 19-20, 2007

David Herald, recipient of IOTA's 1st annual Homer F. DaBoll Award.

 

                   

 

   

 LIGO control room  

Secretary/Treasurer Chad Ellington

        

LIGO's twin kilometer long vacuums 

            

Derald Nye, Hal Povenmire, Richard Nugent  

 

Hal Povenmire and Charles Poplinger

               

Paul Maley and Kerry Coughlin

                 

David Dunham demonstrates his portable equatorial mount 

        

David Dunham

     

Steve Preston and Kerry Coughlin

      

Robert and Elizabeth Moore Observatory, Pasco, Washington

                    

IOTA in Lights

 

Highlights of the 25th IOTA Annual Meeting, 2007

Columbia Basin College, Pasco, Washington

by Richard Nugent, Executive Secretary

The 25th annual meeting of the International Occultation Timing Association was held Friday and Saturday July 20-21, 2007 at Columbia Basin College in Pasco, Washington. This location was chosen to coincide with the occultation by 153 Hilda, a faint outer belt asteroid the night of July 19/20, 2007. Hilda was attempted by several IOTA members and local astronomers in the IOTA Northwest network.. The event occurred at approximately 12:04 AM PDT on July 20th (7:04 UT).  The following individuals provided observations or assisted in the event: David Dunham, Steve Preston, Charles Poplinger, Paul Maley assisted by Art Stithem of the Tri-city Astronomy Club, Steve Dart a member of the Tri-City Astronomy Club, CBC Moore Observatory set up by Tony George, operated by Mike Durst observatory director and assisted by Danny Falla, Tony George in Umatilla Oregon, Joe Garlitz, Chad Ellington and Richard Nugent.  A link to the current reduced data on the event can be found at:

http://www.asteroidoccultation.com/observations/Results/Data2007/20070720_153_HildaProfile.png

 The meeting location was arranged by long term IOTA member Tony George. The final meeting schedule, and most of the presentation files, are at http://iota.jhuapl.edu/iotamt07.htm and on Brad Timerson’s web site: http://www.asteroidoccultation.com/observations/NA/.    

 The next morning, several attendees toured the Laser Interferometer Gravitational-Wave Observatory, (LIGO) in Hanford, Washington. This National Science Foundation funded facility uses particle and wave physics principles along with two perpendicular kilometer long vacuums to search for cosmic ripples in space to detect the effects of gravity waves. Construction was completed in 1999 and initial operation/testing of the detectors began in 2001.

 Friday afternoon, July 20

IOTA Officers and persons present at the afternoon and Saturday meeting included:

President Dr. David Dunham from Maryland,

Vice President Paul Maley from Texas

Executive Secretary Richard Nugent from Texas,

Secretary/Treasurer Chad Ellington from Washington,

Hal Povenmire from Florida,

Charles Poplinger, Danny Falla, and Walt Morgan from California,

Tony George, Bob Anderson and Joe Garlitz from Oregon,

Derald Nye from Arizona,

Steve Dart and Steve Preston from Washington,

Ken Coles from Pennsylvania,

Kerry Coughlin and Roc Fleishman from Baja California sur, Mexico

Video Conference Attendees:

Mary Ellington, Washington

Brad Timerson, New York

Derek Breit, Oregon

Pedro Valdez Sada, Mexico,

Aart Olsen, Illinois

Dale Ireland, Washington

Ed Morana, California

Kazuhisha Miyashita, Japan,

Dave Herald and Hristo Pavlov, Australia

 

Friday, July 20

 Vice-President Paul Maley opened the meeting at 1:40 PM and began with a brief talk on a few of IOTA’s many milestones and stressed the need for an IOTA historian. He recalled the very first time exposure of a star (delta Gem) being grazed in 1979 during a lunar eclipse. Then there was the German account of an Aldebaran graze over two hundred years ago in 1794. In 1954 Leon Stuart photographed a “flash of light” on the Moon which has been thought to be evidence of a meteor impact. In November, 1999 during the Leonid meteor shower, IOTA members made history videotaping the dark side of the Moon and recording brief flashes caused by meteor impacts confirmed at widely separated sites. Maley suggested that IOTA work on an entry in the internet encyclopedia, Wikepedia to illustrate the work and science done by IOTA.  In jest, he also suggested an annual Homer Simpson award, to identify the year’s best IOTA blooper.

 Tony George, the meeting’s host, took over and welcomed the attendees to Pasco and outlined the schedule for the 2-day meeting.

 Business Meeting

 President David Dunham began with introductions of attendees.  Dunham then proposed the distribution of Occultation Newsletter (ON) and IOTA predictions to observers in Australia and New Zealand through the Occultation Section of the Royal Astronomical Society of New Zealand. The method avoids the complications of having overseas dues paid since currently the only way IOTA North America can accept payments are those drawn on a US bank. The proposal was accepted.

 Acting Secretary/Treasurer Chad Ellington talked about using United Merchant Services of California (UMS) for credit card payments for IOTA dues. It has been used 7 times. He recommended switching to the Paypal method for dues payments as it is cheaper plus has the privacy advantage for Paypal users to keep their credit card information secure. A motion was made to drop the UMS method and adopt Paypal as IOTA credit card method of dues payments. There was no opposition and the motion passed. The use of credit cards has not yet been formerly announced to IOTA members, but will be posted soon on the IOTA business website, www.occultations.org

 IOTA’s financial position has remained relatively stable in the previous year. Bank balances are as follows:

 Starting balance 2006  September 16:        $6,504.91

Ending balance  2007  July 13                   $6,621.30

                                       Net Increase:      $   116.39

 Executive Secretary Richard Nugent updated the status of the IOTA Observer’s Handbook. The completed manual was placed on the internet in early April, 2007 and although it had a few grammar issues and minor corrections to be made, Nugent placed it on the internet as a free PDF format e-book entitled: “Chasing The Shadow: The IOTA Occultation Observer’s Manual, The Complete Guide to Observing  Lunar, Grazing, and Asteroid Occultations”.  Many of the grammar and corrections have been made. The manual is located at:

http://www.poyntsource.com/IOTAmanual/index.htm. The webpage has had over 2200 hits in the first 3˝ months. Nugent advertised the manual by emailing to all the astronomy clubs in the USA via AstronomyClubs.com. He plans to continue marketing the manual to overseas astronomy clubs, plus astronomy departments at Universities and colleges. Nugent printed up two-hundred 2-sided flyers to advertise the book at the Texas Star Party and 100 were taken in two days. Alister Lang of Canada requested and received 50 flyers to pass out at the Royal Astronomical Society of Canada’s General Assembly in June. The IOTA Observer’s manual is an important marketing tool for IOTA to reach and recruit more observers worldwide.

 The first week the book hit the website, Dr. W. C Yue of the Hong Kong Astronomical Society wrote Nugent requesting permission to translate the manual into Chinese. Nugent happily agreed. 

 The book has 384 pages, has over 120 figures and diagrams (many in color), an extensive set of references and web resources, a 220 word glossary, a comprehensive set of appendices covering many aspects of occultation work, report forms, equipment setup figures and instructions, shortwave time signal information, IOTA and IOTA-ES annual meeting announcements, tips from IOTA observers and a detailed index. 

 The decision to place the book on line as a free e-book came as no surprise. Only two publishers were willing to publish the book in hardcopy form; Willmann-Bell, Inc, who required 2-3 years to get the book to press and Cambridge University Press, who requested a $75 price tag. The high price and long delay by the two willing publishers (both of which put out only top quality products) was counterproductive to reach IOTA goals – to get the information out as cheaply and as rapidly as possible.

 The on-line book has the advantage that it can be updated easily from time to time as new methods and techniques are developed. It also allows the world to see IOTA’s long celebrated history and numerous original contributions to occultation science.

Elections.  This is an election year for IOTA. Richard Nugent presented the results of the 2007 IOTA election of Officers and Directors. As of the meeting, 45 email votes were received with no additional nominations for any positions. A call for any additional nominations was made of the attendees, and all were in favor of the straight slate of Officers and Director positions. The elected positions are for a 3-year term and they are:

 

President                                                                             David Dunham

Vice President                                                                     Paul Maley

Executive Secretary                                                            Richard Nugent

Secretary/Treasurer                                                             Chad Ellington

V.P. Grazing Occultation Services                                      Mitsuru Sôma

V.P. Planetary Occultation Services                                    Jan Manek

V.P. for Lunar Occultation Services                                    Walt “Rob” Robinson

Editor Occultation Newsletter                                             John Graves

Following the elections, Paul Maley suggested an action item: The need for an IOTA historian which could be an elected position in the future. It is nothing new that many of IOTA’s techniques, observations and history is scattered all over the internet, thru numerous magazine articles and other publications. Ideally a single comprehensive source is needed to identify and recognize IOTA’s long celebrated history. Maley mentioned that former Secretary/Treasurer Art Lucas might be up for the task.

David Dunham continued the business meeting with the presentation of the 1st annual Homer F. DaBoll Award. Homer F. DaBoll had a long history with IOTA right up until his death on March 10, 1990 at the age of 69 in Saint Charles, Illinois.

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 Dr. 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.  Daboll passed away in March 10, 1990 in Saint Charles, Illinois at the age of 69.

The Homer F. DaBoll Awards Committee was formed in 2006 to identify candidates. The committee began with Guy Nason, Canada, Dave Gault, Australia and Tony George, USA.

The 1st recipient of IOTA’s Homer F. DaBoll Award went to David Herald of Canberra, Australia. Herald was presented the award directly from IOTA President Dr. David Dunham at the Royal Astronomical Society of New Zealand conference, June 29 – July 1, 2007. David Herald is the author of the widely acclaimed program, Occult, which predicts all types of occultation events, eclipses, transits and has maintained the database of all observed asteroid occultations, plus lunar limb data from grazes and total occultation observations used by Occult.  Rapid, easily made predictions and data analysis would not be possible without Herald’s Occult program, which has been used since the early 1990’s worldwide by occultation observers. A new annual award was suggested for exceptional observations, the David E. Laird Award. It was motioned and approved.

Paul Maley updated the status of IOTA’s non profit position as a 501(c) IRS tax-exempt Texas corporation. In March 2007 Maley filed the forms necessary to maintain IOTA’s non-profit tax exempt status with the Texas Secretary of State Corporations Section at a cost of $5.00. These reports are due every four years.

Another issue with IOTA (and amateur astronomy in general) is public outreach and the continual need for new blood in the organization. Derek Breit suggested bringing school children to the 9 Metis asteroid occultation of 6.0-mag. ZC 462 on Thursday evening, September 11, 2008, near the proposed location for the 2008 IOTA meeting. In California the event occurs slightly after 10 PM local time thus providing the opportunity for students to observe and obtain timings for this 50-second maximum event. 

An issue with this scenario is legal liability. Like any star party in a parking lot or public place it was suggested that IOTA obtain liability insurance as many astronomy clubs across the nation have. Another way to provide liability coverage is to have a local astronomy club with insurance coverage sponsor the event for IOTA. Derek Breit sent an instant message via the video conference link and will look into this.

Maley suggested standardizing the IOTA website to make it connect to other IOTA websites easier. The main IOTA website has improved greatly in the past few years as an easy to navigate page to the various IOTA related fields, observations, equipment, techniques, observation results, etc., but more is needed. A single website link to all worldwide observations is needed. With easy to find results of observations in a simple to understand format, this will reflect positively on IOTA and its sister organizations.

On the subject of promoting occultations and amateur astronomy, recently Charles Poplinger made an observation in a Post Office parking lot and nine persons showed up to watch. It’s nothing new that people are fascinated about telescopes and amateur astronomy in the general sense. It’s up to all IOTA members worldwide to encourage, promote and recruit new astronomers.

With no further business, at 3:07 PM, Dunham motioned that the business part of the meeting be closed, and it was seconded. A 15 minute break was taken.

Technical Sessions

David Dunham has now celebrated his 50 year involvement in occultation astronomy. One of the highlights of his career started in 1963 with the first ever grazing occultation map published in Sky and Telescope magazine. Other highlights include the duplicity found in µ Areitis in January 1970, separation = 0.03".  This observation was made by Dunham and C. de Vegt (Hamburg, Germany). In August 1973 a possible 3rd component was found 0.2" of the pair. The next opportunity to confirm this duplicity came in December 1973 after the annular eclipse. Just recently this star grazed the waning crescent  Moon on June 12, 2007 at Hockley, Texas (40 miles northwest of Houston). Seven observers had stations for this graze including Richard Nugent who was the most northerly observer with a single 1-second event.

News from the Space program included the planned launch of the Lunar Reconaissance Orbiter (LRO) in 2008 and other lunar missions then or soon thereafter. LRO will be in a polar orbit and its laser altimeter is expected to provide elevations accurate to 1-meter. Dunham’s NASA intern, Zane Nitzkorski, is working on formatting IOTA’s historical graze data, He is updating IOTA’s graze database 1965 – 1990. His last day is August 10th and he is not expected to finish the project. Ken Coles was willing to help finish this important database project. The graze observations are becoming of interest since they can potentially give accurate measurements of ridges in the polar area that may help planning observations by LRO and by other lunar satellites.

Dunham summarized some recent asteroid occultation results for North America:  

99 Dike Dec 1, 2005. The profile showed a close double star.

25 Phocaea Oct 3, 2006. Brad Timerson’s video showed a double disappearance, showing a crater/valley on the northwest portion of the asteroid. 86.1 x 72.1 km

200 Dynamene Oct 9, 2006. A widely observed event in the USA and 20 minutes earlier it was observed in Europe. Fourteen observers had occultations, Dynamene’s estimated size came to 123.7 x 132.5 km.

409 Aspasia Dec 20, 2006. An observed event in which Dunham’s remote station lost the target star about 10s before it was probably occulted at that site (the file shows no occultation there, but that probably wasn’t the case, we don’t know, provision should be made for such uncertain observations). Aspasia’s size was estimated as 194 x 165.7 km.

697 Galilea  Jan 8, 2007, 4 observations from  California. 88.5 x 62.1 km

44 Nysa Jan 10, 2007. 49.9 x 100.1 km.

372 Palma Jan 26, 2007. A widely observed event with 20 positive observations. 183.5 x 206.8 km.    

55 Pandora Feb 18, 2007. 91.0 x 57.7 km.

88 Thisbe Feb 21, 2007. 166 x 217.8 km.

411 Xanthe Apr 18, 2007. 72.3 x 83.7 km. The gradual  D and R of this star from some of the videos indicated a giant star likely on the order of 20-25 R?.

99 Dike Apr 22, 2007. 56,2 x 73.8 km (1st asteroid with 2 remote success occultations.)

471 Papagena May 24, 2007.  150 x 106 km (Dunham recorded it from 3 separate places).

192 Nausikaa July 10, 2007. 78.5 x 118.2 km.

225 Henrietta July 16, 2007.  149.9 x 87.7 km.

153 Hilda July 20, 2007. 185.2 x 145.3 km.

 Chad Ellington gave a brief wrap up of the previous night’s 153 Hilda event. It had ten positive events from the attendees (see list above and link to Brad Timerson’s website for results).

 Richard Nugent presented some useful tips for occultation observers. These tips were largely taken from Appendix P of the IOTA Observer’s Manual. These tips contain those solicited from many occultation observer’s experience over the years. Upon mentioning the “Why Occultation Flyer”, Maley suggested renaming it to “Observing Eclipses of Stars by Asteroids”. The word “Occult” seems to have a negative connotation among the general public and this suggested change could help improve IOTA methods of marketing its activities.

 David Dunham presented the methods used for remote video stations for occultation observations. Use of an unattended remote station can double (or triple) the number of stations for an observer’s graze or asteroid event. He mentioned Derek Breit’s website has time offsets for pointing to candidate target stars when using remote video stations. The first remote video station used for an asteroid occultation was the Sep 7, 2001 event of 9 Metis in California.  To date, 21 occultations have been successfully recorded (positive) from 2 or more remote and attended stations, most run by Dunham and Roger Venable. Dunham suggested observers can increase their number of occultation attempts by planning vacations at or near the path of asteroid and grazing occultations. Most IOTA observers have portable systems and that makes it that much easier to have a “grab and go” occultation system ready.

 Dunham demonstrated his portable equatorial mount (made by the now out of business company Roger Tuthill, Inc.). It fits in a suitcase and is adjustable to a wide range of latitudes and holds a Celestron-8 easily.

 Paul Maley talked about the 30th anniversary of the first possible asteroid moon discovery on March 5, 1977 when he observed a 0.5 second event near Victoria, Texas. His location was some 900km north of the actual path of the asteroid 6 Hebe that crossed over Mexico.  It is of great concern that after 30 years of occultation observing, IOTA has yet to discover and confirm an asteroid moon, while the professional astronomers have 107 candidate suspected and/or confirmed asteroid moons. There have been 42 suspected secondary events based our history of observed asteroid occultations. The most likely candidates for discovering asteroid moons probably comes from NEA’s (Near Earth Asteroids). Their smaller size means a smaller distance between the primary and any secondary object increasing the chance for an occultation observation. 

 Through 2006, 1,029 asteroid occultations have been observed. Another suspected asteroid moon observation may have been made before Maley’s: Hal Povenmire’s October 12, 1974  0.7-second occultation during the 129 Antigone event in south Florida. Although there were no other observations made of Antigone on that date, the path of Antigone was well south of Povenmire in central America, based on measurements of plates taken the night of the event. This path of 129 Antigone and Povenmire’s location is shown in Figure 12.1 of the IOTA Occultation Observer’s manual.   

 This Technical Session ended at 6 PM and the discussions continued at dinner at the Red Lion hotel restaurant.

 Saturday, July 21, 9 AM

 The meeting continued with a webcast presentation by Dave Herald of Australia. Herald discussed the determination and archiving of astrometric positions derived from occultation observations. Currently the data from asteroid occultations are stored in the database of the Occult program and also at NASA’s Planetary Data System by Herald and Dunham. 

 Herald has been involved in the reporting of astrometric positions of comets with the Minor Planet Center (MPC) since 1972. He realized that an asteroid occultation can give more accurate astrometric position of the asteroid than a CCD camera using a least squares adjustment and changed the Occult program to do this.  The MPC became interested in this new method of determining astrometric positions and developed routines to read the data from the Occult program. Herald’s decision to report positions derived from asteroid events would rest on the residuals in the final set of observations. If there were large deviations from the MPC’s data, he would not report a position. This would preserve’s IOTA’s reputation which is looked at with skepticism by some. The MPC has allocated observatory code 244 for positions derived from asteroid occultations.  

 Occult’s positions can be updated immediately when the GAIA (Global Astrometric Interferomter for Astrophysics)  satellite results become available. GAIA star positions are expected to reach 20 microarcsecond accuracy (0.000020") to visual magnitude15.  Currently, positions derived from well observed asteroid events are in the range of 100-200 µsec (±0.0002"). With 3-5 observations, a position accurate to ±0.003" can be derived. For single chord observations, the error is set at the apparent diameter of the asteroid. It is interesting to note at this precision, relativistic bending of light by the Sun is quite significant at a 90 degree solar elongation. Single chord observations have the highest inherent uncertainty with no corroborative observations. But a great majority of single chord events are reported and virtually all multi-chord events are reported.

 Hristo Pavlov gave a webcast presentation on the new program, Occultwatcher. With the program running on a computer, it will notify observers of any path updates in real time from Steve Preston’s asteroid occultation website. Observer’s can input their position on a Google map and see the other observer’s locations in real time. Even the method of recording is displayed for each observer. Dunham asked if the program could have automatic email notification of events. The program can notify the observers but only if the program is running on their computer.

 Tony George presented results of the Hiraoka occultation he observed on May 26, 2006. It was a low probability event with a predicted maximum duration of 0.2 seconds. Using a 12" Meade LX-200 and the Watec 902 Ultimate video camera, his limiting magnitude is in the range of +12 - +12.5.

 His visual inspection of his recording of the Hiraoka video initially did not show any occultation. Further analysis using LiMovie showed 7 frames with a drop in brightness. To verify the occultation was real he looked at two field stars in the video.  Both field stars showed no change in brightness during the time of the occultation. Dr. Michael Richmond did further analysis of the video and he agreed with George’s findings.  Dave Herald used the occultation and derived an astrometric position of Hiraoka in good agreement with existing MPC data. For these extraordinary events, Herald requests Limovie plots to substantiate the astrometric position. Another possibly raised was that this occultation event could be by a satellite of Hiraoka.

 David Dunham brought the attendees up to date on the status of asteroid occultation collections. The Europeans have an excellent well organized website, Euraster.net. It gives the details of every asteroid event observed in Europe since 1997.

 In 2006 Brad Timerson created and now maintains a website for North American asteroid events. Currently it covers part of 2006 and all 2007 events and has an easy to follow format. All positive events display an Occult profile, a map of observer locations, observer names and event times. Timerson also created a new semi-automated asteroid occultation report form, standardizing the many different reporting formats used by observers over the past 10 years. North American reports should be sent to Reports@asteroidoccultation.com 

 Steve Preston continued with the current astrometry process he uses for the asteroid occultation predictions. Currently positions are obtained from the USNO 0.2-meter FASTT telescope located in Flagstaff, Arizona. This telescope system observes asteroids numbered 2000 and less with accuracies of 100mas (milli arc-seconds, 0.01") on the Tycho-2 reference frame. In 2006, additional asteroids were added to the observing runs.

 A second source Preston uses for astrometric positions is from Table Mountain Observatory (TMO) from Bill Owen. Owen has 8-10 observing runs/year observing 30+ objects per night for two or three nights in a row. Many of his targets are those prioritized by IOTA. TMO’s accuracy is slightly better than FASTT, ~80 mas. TMO uses the UCAC2 reference frame (U.S. Naval Observatory CCD Astrograph Catalog). A third source for positions comes from Raoul Behrend in Geneva. He occasionally provides positions for Preston a few times per year for individual objects of particular interest. His positions are also on the UCAC2 reference frame with accuracy similar to FASTT (100 mas). (The U.S. Naval Observatory’s website is announcing the release of the UCAC3 in early 2008, creating a new reference frame).

 Preston’s procedure for updating asteroid orbits includes using historical data from the MPC plus allowing for perturbations from the 13 largest asteroids. Stellar position data is taken from several catalogues, Tycho-2, Hipparcos, FK6, UCAC2. Preston is careful not to mix UCAC2 proper motions with Hipparcos mean positions since they are on different reference frames.      

 With several high accuracy star catalogs available, one might think this is good for astrometry in general. The situation is that each catalog defines a unique reference frame which cannot necessarily be “averaged” with the others, without the systematic differences accounted for.  This is not a trivial task. In order to keep asteroid occultation predictions accurate, we will need newer more accurate star catalogs (from the European GAIA astrometry proposed satellite). The positional accuracy from the older catalogs in use is deteriorating due to the errors in the proper motions. Another issue is perturbations by smaller asteroids which goes back to a basic problem in celestial mechanics theory.

 Paul Maley commented on the station sorts on Derek Breit’s website. A typical station sort list for an asteroid event has way too many stations allegedly manned by persons that either don’t exist or won’t be observing the event. This creates confusion for newer and willing observers as they think that there is no way they can contribute data with 100 other observers competing for stations.  Experienced (and mobile) observers don’t really know who is covering what station making it difficult to choose a place to observe. A simpler, easier station list with confirmed observers was suggested.      

 David Dunham gave a Pluto Occultation summary from the March 18, 2007 event visible over the central and western USA. Tony George observed the event using the Robert and Elizabeth Moore observatory’s 16 inch Meade LX-200 and Meade DSI CCD camera at Columbia Basin College. Even due to the very low altitude of Pluto at 12 degrees, he obtained data showing the disappearance but his imaging was stopped before the reappearance. He obtained a total of 129 images showing the occultation duration at 642 seconds. His preliminary results showed:

                   D    = 10:52: 02.7 UT

                   Dend = 10:52:37.03 UT 

A link to Tony’s PowerPoint presentation can be found at:

http://www.asteroidoccultation.com/observations/NA/PlutoOccultation2007.ppt

This long duration of the disappearance of the target star is due to Pluto’s atmosphere. This important observation illustrates that good science can be done with amateur equipment rivaling those of professional observatories. Richard Nugent attempted the occultation from McDonald Observatory in Ft. Davis, Texas, but clouds moved in just a few minutes before the disappearance. Paul Maley observed from George Observatory south of Houston, Texas with a 36-inch reflector but the actual occultation path was north of this site; a LiMovie analysis showed no occultation took place there.

Tony George then discussed the use of LiMovie and Registax for the analysis of occultation videos. Registax has options to combine video frames (stacking) to bring out fainter stars but at the same time the data’s time resolution is compromised. For example, if you use a 5-frame integration, this limits your time resolution to 30/5 = 6 frames/sec or 0.1667-second  time resolution compared to 0.03-second for 30 frames/sec normal videos.

A link to Tony George’s PowerPoint presentation can be found at:

http://www.asteroidoccultation.com/observations/NA/HiraokaOccultation.ppt

and to his word file documenting this event can be found at:

http://spiff.rit.edu/richmond/occult/hiraoka_may2006/Observation_of_a_Very_Small_Asteroid.doc

A link to Michael Richmond’s analysis can be found at:

http://spiff.rit.edu/richmond/occult/hiraoka_may2006/hiraoka_may2006.html#prob

Bob Anderson presented his new program, OccuLAR (Occultation LiMovie Analysis Routine). This new software detects and determines the ‘D’ and ‘R’ times of occultation events from LiMovie files. Occular takes advantage of the fact that Limovie’s signal and noise data is Gaussian. This allows use of least squares to analyze the Limovie data. The user is prompted to input preliminary start and end times of the LiMovie data and several other  parameters. Tony George demonstrated use of the program with last year’s Hiraoka occultation with excellent results compared to a visual analysis of the video frames. The program was released to the attendees.

A link to Bob Anderson’s PowerPoint presentation can be found at:

http://www.asteroidoccultation.com/observations/NA/FinalOccular.ppt

And a link to download the program can be found at:

http://www.asteroidoccultation.com/observations/NA/ (see link at center bottom of the page).  A Word file is also provide as documentation on how to operate Occular.

Following a lunch break, Paul Maley updated the meeting on his future plans for solar eclipse expeditions in IOTA’s continuing study to measure possible solar radius variations. The next eclipse effort is August 1, 2008 over China with a proposed southern limit observing site near the city of Hami. Currently, the northern limit is not covered. For July, 2009 Maley is seeking permission from the Japanese government to have a small team of observers watch this long eclipse over Iwo Jima. For a later annular eclipse, proposed observing sites for eclipse limits will be Sumatra (north edge) and Java (south edge). Two future eclipses cross the USA, May 20, 2012 (annular) and August 21, 2017 (total). Both north and south limits have no coverage problems with these eclipses.    

Brad Timerson (via a Word file) presented the status of the asteroid reporting for North America. Following the 25 Phocaea event in October 2006, he sought to standardize the reporting of North American asteroid occultations. Prior to the new reporting form he devised, asteroid occultation reports went to various persons sometimes using a non-standard text form and/or via the body of an email. The problem with using a non standard format is that important data (such as telescope used, sky conditions, timing methods) were frequently left out. This resulted in further communications by email to the observers to obtain these data.  Timerson devised an Excel reporting form that is now processed with an Excel Macro (written by John Talbot) instantly putting the data into Occult OBS file format. This method also largely eliminates transcription errors when converting the data to Occult format for analysis.  Timerson also created a new easy to follow North American asteroid occultation results webpage on Steve Preston’s server, which also includes report form templates for upcoming occultations. 

David Dunham updated the meeting with results from two more solar eclipses analyzed per an existing NASA grant. In September, 2005 Dunham presented IOTA’s solar radius research at the SORCE meeting in Colorado. He mentioned new results from Gideon Bass’s analysis of eclipses from September 1987 and May 1900.

Steve Preston reported on the EuroPlanet Occultation Symposium organized by Bruno Sicardy. One goal of this symposium was to improve the techniques and chances of observing Pluto and other Trans Neptunian Object (TNO) occultations. One piece of hardware proposed for such events is an occultation camera currently being developed. Some of its features are a high signal to low noise ratio, frame based and a high video rate. One estimate for the cost of this camera was around 2k – 3k US dollars. Preston agreed to help compute orbits for TNO’s. Another important goal was amateur/professional collaboration in observing these faint (mag = +14, +15) events. David Herald is assisting also – he has updated the Occult program, to search for TNO events.  

David Dunham attended the Trans-Tasman Occultation Symposium in Auckland, New Zealand on July 1-2, 2007. Dunham was also a featured speaker at the preceding meeting of the Royal Astronomical Society of New Zealand (which covered a large part of his travel costs) and he spoke about his career in space flight mechanics along with his involvement with IOTA.

Walt Morgan presented a paper on obtaining accurate horizontal and vertical coordinates from GPS receivers. It’s well known that elevations obtained from GPS receivers are not necessarily accurate as compared to USGS TOPO maps. Morgan experimented with a KIWI GPS time inserter which uses the Garmin GPS-18 receiver. He did a series of eight tests at four stations near Livermore, CA. Four of the sites were National Geodetic Survey benchmarks with positions and elevations known to high accuracy. By utilizing the data from the KIWI unit and a correction for the ellipsoid height, Morgan showed that GPS receivers can produce accurate elevations needed for occultation work. One of the results that came from this study was the need for GPS users to wait at least 3 minutes before utilizing their GPS positions. Accuracy is related to the number of satellites used by GPS units. It was recommended that users wait between 3 and 10 minutes to allow GPS units to acquire more satellites. This wait time also allows effects of the Earth’s ionosphere to be averaged out by the receiver.

Paul Maley described the proposed Clay Center Mobile Observatory. This would be a mobile observatory with a series of 10-inch SCT telescopes, a Lumenera Skynyx 2-0 high speed CCD camera (with advertised 60 frames/sec frame rate) deployed at regular intervals by a 2006 Dodge Sprinter Van to record occultations. These systems would be remote unattended stations controlled by one small laptop or remote control via ham radio and/or custom software. The Dodge van has a custom interior for telescope storage and doubles as a control room for the remote units.

Paul Maley proposed the meeting site for the 2009 IOTA meeting be at Clay Center in Brookline, Massachusetts. The location has excellent meeting facilities and an observatory with a 25-inch  telescope. More details are to follow.

David Dunham showed maps of some remaining favorable grazes and asteroid events for the remainder of 2007. Dunham mentioned that Sky and Telescope has reduced the space available to him for his yearly Lunar Grazing Occultation Highlights (published since 1968) so he now places most of the maps and data at http://iota.jhuapl.edu/grazemap.htm. On Bob Sandy’s website are additional grazes that are within 200 miles of his location in Blue Springs, Missouri.  One interesting event remaining in 2007 is the occultation of Mars by the Moon on December 23, 2007.

For 2008, June 30 the 11% illuminated Moon will graze Taygeta and Asterope.

May 11, 2008 – Epsilon Cancri, a m= 6.3 star which is a suspected binary.

Asteroid Events:

Sep 27, 2007: Pluto occults a m= 8.7 star, but the path misses the Earth !  The shadow for Pluto’s Moon Charon might go over SE Asia but will probably also just miss the Earth. Walker Vaning suggests that observers around the world (but especially those around the Indian Ocean) should monitor the star for occultations by possible rings of Pluto that he has mapped from previous occultation data.

August 15, 2007: 558 Carmen, m = 8.3 star over southern Texas

August 21, 2007: 146 Lucina, m= 8.2 star Michigan. A 1982 video recording may have found a satellite of Lucina.

September 20, 2007: 146 Lucina, m = 7.9 star in northern California.

November 10, 2007: 15 Eunomia, m = 9.5 star

December 18, 2007: 219 Thusnelda, m = 6.7 star, South Florida, Mexico, Spain.

December 20, 2007: 187 Lamberta: m = 9.4 star, Virginia to California.

 March 9, 2008: 45 Eugenia, m = 5.7 star, Baja California, Mexico. Eugenia has a known satellite. Kerry Coughlin and Roc Fleishman are planning on coordinating this outstanding event. 

March 14, 2008: 337 Devosa, m = 7.4 star, Japan and Baja California, Mexico.

September 12, 2008: 9 Metis, m = 6.0 star, California to Michigan. Apple Valley, California is the proposed site for IOTA’s 2008 meeting just after this event.

 November 23, 2008: 98 Ianthe, m = 8.4 star. This is a low altitude event over the extreme NE USA.

 At 4:49 PM the meeting ended.   Following this Chad Ellington announced the three door prizes donated by Adirondak Video Astronomy (New York) and PFD systems (Bethesda, Maryland). Two PC-164C Supercircuits cameras with power supplies were given away and one KIWI GPS time inserter. IOTA thanks these companies for their support.

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.