The International Occultation Timing Association Annual Meeting at Avila College, Kansas City, Kansas
June 11-12, 2000
Watching Graze video's with a Supercircuits Camera
Highlights of the 18th
2000 IOTA Annual Meeting
Avila College in Kansas City, Kansas
By Richard Nugent, Executive Secretary
The 18th annual meeting of the International Occultation Timing Association was held Saturday and Sunday June 11-12, 2000 at Avila College in Kansas City, Kansas in conjunction with the Astronomical League’s 50th anniversary meeting of its Mid States regional convention (Mid-Con). This meeting place was chosen because of its central location along with the opportunity to expand and disseminate knowledge and information about IOTA’a activities to members attending Mid-Con.
Sixteen members and attendees were present at the meeting and included:
President David W. Dunham from Maryland,
Secretary-Treasurers Craig and Terri McManus from Kansas,
Executive Secretary Richard Nugent from Texas,
Dr. Wayne Warren, Jr. and Harry E. Bates from Maryland,
Walt “Rob” Robinson and Nick Ruess from Kansas,
Clive and Beryl Cadle from Oklahoma,
Bob Sandy, Wayne Clark and Jerry Kennedy from Missouri,
Hal Povenmire from Florida,
Marilyn Burke from Texas,
Danny Falla from California.
At 10:30 AM President David Dunham opened the meeting and asked attendees to introduce themselves. Following the introductions, there was a brief discussion about the fact that IOTA members were charged a registration fee for the Mid-Con convention. It was stated that at no other meeting in IOTA history have there been a fee for use of facilities or for a registration fee, although that strictly speaking was not the case. In 1995, IOTA held its meeting in conjunction with the Astronomical League’s annual meeting in San Antonio, and earlier it was held one year in conjunction with the Texas Star Party, both of which had registrations. However the Mid-Con people normally charge for their annual meetings to cover costs of facilities and to attract high profile speakers in constantly changing fields of astronomy. An obvious benefit was the cheap room rates offered at the college dormitory compared to those of local hotels.
GPS, S/A DEVELOPMENTS - Dr. Wayne Warren, Jr. discussed the recent development of the Government turning off the Selective Availability (S/A) function on the Global Positioning Satellites (GPS) system on May 2, 2000. S/A and the GPS system has been in the control of the US Military since the launch of the GPS constellation of satellites and has been kept “on” for Military reasons. S/A was used to scramble GPS signals so that receivers on the ground could only obtain positional accuracy of latitude and longitude coordinates to approximately 30 meters precision. This accuracy has long been known to be unacceptable for IOTA activities and could only be worked around by the differential corrections procedure (DC or DGPS). And in foreign countries, where accurate coordinates were needed for solar eclipse limit observations, time consuming arrangements had to be made with “friendly” institutions to establish an accurate base station (benchmark) for computing relative coordinates for these one time events. With DC, 1-2 hours of GPS readings had to be taken in order to collect enough data points for later computer reduction in order to obtain 2-3 meter accuracy. In addition, only GPS receivers capable of collecting and storing thousands of data points could be used to obtain such accurate coordinates. In this regard, Vice-President Paul Maley had negotiated the loaning of a very sophisticated GPS receiver from Trimble Navigation in California over the past 8 years for use on solar eclipse expeditions. This particular Trimble Navigation GPS receiver has a retail price of over $2,500 so understandably it was not financially feasible to just go out and buy one like a tape recorder or video system. With the S/A now turned off, 5-meter accuracy in one’s position can now be obtained in about 10 minutes with virtually any GPS receiver, as long as there is good satellite geometry!!!
Dr. Warren described a Magellan GPS receiver he had just ordered along with a software package from a company called Fugawi that downloads data directly into a computer. The Magellan receiver cost about $250 and the software about $80 at the time of this writing. While this discussion continued, Dr. Frank Miller passed around a Magellan 2000 receiver for attendees to see. Preliminary tests by Dr. Warren with the S/A turned off yielded an astounding 1.5 meter accuracy after a few tests. Dunham says that 10 minutes should be sufficient to obtain excellent positional results. Compared to just 2 or 3 minutes of data collection by the GPS receiver, 10 minutes could average out signal fluctuations caused by the Earth’s ionosphere. Along this item, Dr. Warren said he would like to see a program to do interactive GPS measurements. This would allow the user to see ionosphere fluctuations in real time.
Despite all the excitement with the S/A scrambling function now turned off, Bob Sandy mentioned that he still routinely gets accurate positions from the USGS maps. But the problem with the maps is that they are quoted to show 95% of the mapped features to within 40 feet of their true positions, just barely within IOTA’s requirement of 15 meters. At best, USGS maps can only provide 40-foot accuracy - and again - it requires extra time to obtain, and measure the maps.
Even with the S/A function turned off there is still the problem of obtaining accurate elevations of the observation site. GPS altitudes are still below par and users can use the USGS maps to get the elevations. USGS maps are currently available at www.topozone.com, where observers can read off the elevation for their particular observing site.
Dr. Warren had also showed results for a digital raster-graphics map to plot graze data for the graze of 18 (() Geminorum, a spectroscopic binary of sub arcsecond separation, from February 15, 2000 in Largo, Maryland. In this case the position angle and distance can be plotted of the binary for orbital analysis.
Danny Falla then briefly discussed a program he wrote in basic to compute latitude, longitude positions from USGS maps. Following this around 11: 15 AM the attendees broke the meeting to join the Mid-Con meeting where IOTA had a scheduled presentation.
MID-CON Meeting, 11:15 AM Saturday
Joining the Mid-Con meeting, Walt “Rob” Robinson talked about IOTA’s beginnings when a 14 year old boy David Dunham received a 60mm refractor for Christmas in December 1956. This sparked an interest in astronomy, especially positional astronomy and celestial mechanics. On September 18, 1962, Dunham succeeded in predicting his first grazing occultation using a FORTRAN computer program. As IOTA grew in size and scope of observations, predictions and results, IOTA was formally established in 1975 and incorporated in 1983 in Texas as a non profit corporation. Other highlights in IOTA’s history Walt “Rob” Robinson mentioned:
May 1990 - IOTA published in the Astronomical Journal the shape of the asteroid Pallas from 131 chords,
1995 - First email notification of occultation events compared to telephone notification in prior years.
The International Lunar Occultation Centre (ILOC) in Japan to date has catalogued some 250,000 total occultations since 1980, and over 18,000 graze events. These are analyzed by ILOC and the data distributed worldwide to astronomers.
Walt introduced IOTA’s President Dr. David Dunham to the Mid-Con meeting. Dunham then briefly described some of his work with the Applied Physics Laboratory at the John Hopkins University on the NEAR mission to the asteroid EROS and his role in the computation of orbits.
David Dunham wasted no time and showed the group how IOTA’s efforts resulted in the first confirmed meteoritic impacts on the Moon during the Leonid meteor shower last November 18, 1999. The visual sighting of a “flash” on the Moon’s dark side was made by Houston Astronomical Society (HAS) member Brian Cudnik at the HAS observatory in Columbus, Texas. Cudnik was talking to IOTA Executive Secretary Richard Nugent while observing through a Celestron 14 telescope when he saw the flash. Cudnik immediately recorded the time (4:46:20 UT, November 18, 1999) and estimated the magnitude at about +4. (Unfortunately, Nugent had turned off his video system outside the Observatory building just minutes before going in to talk to Cudnik !!). Cudnik contacted Dunham the next day for possible confirmation. Fortunately, Dunham was video recording the Moon’s dark side with a 5'' telescope in Mt. Airy, MD. Dunham described how he anxiously reviewed his video tape of the Moon and at the exact time that Cudnik had reported - there was indeed a flash visible on the tape. The flash only appeared on two video frames, but it did appear. The flash was also seen by Steve Hendrix in Cameron, Missouri.
Five other impacts were soon identified by Pedro Valdez Sada near Monterey, Mexico and by David Palmer in Greenbelt, Maryland. Dunham confirmed these events also on his videotape. Dunham showed the location of the 6 confirmed impact flashes from that November 18 night on a Moon map. The flash positions have been determined to an accuracy of about 2 degrees. The analysis of these flashes has seemed to have ruled out artificial satellites, since all low satellites were in the Earth’s shadow at the time (events all near local midnight) and none of the geosynchronous satellites were within 3 degrees of the Moon at the time. Dunham proceeded to show a video of the November 18, 1999 impact flashes. Other events showed on video were image intensified occultations of stars in the Praesepe cluster, three asteroidal occultations in Jan. 1991, a graze of 97 Tauri in July 1995 (including events of a newly-discovered companion), and a graze of an 8th-mag. star in May 1995.
Dunham commented that asteroid occultations with the HIPPARCOS and TYCHO catalogs available have made this an exciting new field for amateur with relatively inexpensive video equipment. Dunham then showed some asteroid profiles:
308 Polyxo - from January 10, 2000, Four (4) chords were obtained including the first successful chord from an F-14 aircraft. This observation was made by Southwest Research Institute astronomers Drs. Dan Durda and Alan Stern. Other chords observed were by Richard Nugent, Joe Hobart, and John Sanford.
Eros - from January 24, 1975
911 Agamemnon - from March 21, 2000, only 2 chords.
216 Kleopatra - from May 5, 2000 issue of SCIENCE, shape profile was obtained from updated radar equipment from the Arecibo Radio Telescope in Puerto Rico. [See the separate article about this asteroid.]
Dunham then showed a few viewgraphs of some upcoming occultations events for this year including the spectacular 752 Sulamitis event in which the m = +2.9 mag star ( Geminorum will be occulted for up to 13 seconds. This is the brightest star being occulted in recent history anywhere over land. (Two years ago April 10, 1998, the 1st magnitude star Regulus was occulted by an asteroid somewhere over the Pacific Ocean north of Hawaii).
Following Dunham’s presentation Walt Robinson described all of IOTA’s websites which contain usueful updated and time critical information on occultations and grazes along with an archive of articles on nearly all aspects of occultations.
12:00 noon, and the meeting broke for lunch.
At 1:25 PM IOTA attendees began the business meeting separate from the Mid-Con meeting.
FINANCIAL REPORT, Craig and Terri McManus read their report which showed IOTA to be in good financial shape with $5,633.94 in the checking account as of June 6, 2000. For the period March 31, 1999 through June 9, 2000 there was a small cash flow of $27.22. The cash flow report is shown below:
Cash Flow Report
3/31/99 Through 6/9/00
Back issues 15.00
Interest Inc 98.03
Member dues 2,840.00
TOTAL INCOME 3,341.03
Card Cost 49.62
Internet Cost 526.89
Office Supplies 84.64
TOTAL EXPENSES 3,313.81
OVERALL TOTAL CHANGE 27.22
Craig remarked that IOTA has currently 277 members consisting of 181 full “paper” members, (“paper” members receive paper copies of the Occultation Newsletter as opposed to receiving them online), 20 members online, thus leaving 75 members who receive additional mailings (Asteroid Occultation supplements and updates).
David Dunham motioned the members present to accept the financial report as it was presented and the motion was seconded. The motion carried without any opposition.
IOTA MANUAL STATUS - Wayne Warren is currently working on the IOTA manual. He is currently investigating converting it from GML to a script format such as Microsoft Word. Warren reported there are problems in the conversion of tables and some equations to Word format. However, once the conversion is complete to Word format, the manual can easily be converted to PDF (ADOBE) and other formats. The manual is currently about 120 pages long and several runs will have to be made to work out the bugs. The manual is now currently on a hidden URL on the IOTA web site in a zip file. Craig and Terri McManus have several hard copies of the manual and will send one to anyone who requests it.
PUBLICATION REPORT - In Rex Easton’s absence, David Dunham updated the attendees on IOTA’s Occultation Newsletter (ON) publication status. ON is far behind schedule. This is especially frustrating for institutional subscribers. Dunham proposed that IOTA members volunteer to assist in the publishing of back issues of ON until caught up. It was decided that Volume 8, No’s 2, 3 and 4 be published by the end of 2000 with Volume 9 starting in 2001. Dunham assigned the August issue editorial assistance duties to Richard Nugent, October to Wayne Warren, and December to Craig and Terri McManus.
Craig McManus reminded the attendees of the high cost of publishing and postage for ON. A typical issue costs $585 to print (at discounted rates) and postage runs approximately $525. In addition the Asteroid Supplement costs around $720 for printing only!! Richard Nugent suggested the possibility of getting a discount non profit postage rate, however IOTA doesn’t do enough volume to warrant the fees charged by the post office for such rates or to switching to bulk mail rates. Craig McManus mentioned that air printed matter is the preferred way to send issues to other continents.
1999 MINUTES: Richard Nugent gave a brief presentation of the highlights of the minutes for the 1999 IOTA meeting in Denver. The minutes have been in a draft form (unpublished) since June 1999 awaiting Dunham’s review since a good part of that meeting was Dunham’s own personal history into occultations and grazes from the early 1960’s. It was important to have this information proofed by Dunham regarding IOTA’s early beginnings so that 21st century readers of ON would have accurate historical information about the earliest occultations, grazes and the start of IOTA as a new important branch of astronomy. The minutes should be ready for the next ON issue (actually, they are in this issue).
David Dunham briefly discussed meetings in which IOTA will have a presence: The European Symposium on Occultation Projects (ESOP) and amateur-professional collaboration in the U.S. Dunham and B. Timerson published an abstract detailing the amateur-professional collaboration IOTA has enjoyed over the years, and presented by Dunham at the American Astronomical Society’s meeting in Rochester, NY, on June 5. Amateur and professional observers have used total and grazing lunar occultations to further refine the lunar limb profile. This highly accurate profile has been used to identify Baily’s Beads during solar eclipses to measure small variations in the solar diameter. IOTA has also worked closely with professional astronomers on all aspects of asteroid occultations. Once a difficult field due to the larger errors in the predictions, it is now a growing new field due to the highly accurate HIPPARCOS reference frame. Some 26 asteroid occultations were observed in 1999 alone in part due to the accurate astrometry work of Ron Stone at the U.S. Naval Observatory in Flagstaff, AZ and by Bill Owen at the Jet Propulsion Lab’s Table Mountain Observatory in California.
IOTA PUBLICITY: IOTA had important publicity with the recent derived shape profile of asteroid 216 Kleopatra, acknowledging IOTA’s independent discovery of its shape from an observed occultation from January 19, 1991. IOTA was acknowledged in a paper in which the shape profile of Kleopatra was published using the recently upgraded radar equipment with the radio dish at Arecibo in Puerto Rico. [See the separate article about Kleopatra and IOTA’s role.] Kleopatra was also observed using the new 10 meter Keck Telescope on November 19, 1999 using adaptive optics once again confirming the cigar shape of this asteroid. (Sky and Telescope, April 2000, page 17). IOTA also made headlines in the news and on internet news sites with the video recording and confirmation of meteor impacts on the Moon from the Leonid meteor shower from last November 18, 1999. The confirmed video impact flashes on the Moon’s surface from a Leonid meteor made the Astronomy Picture of the Day (APOD) for December 8, 1999 (www.antwrp.gsfc.nasa.gov/apod/astropix.html).
IOTA/ES ESOP NEWS: Dunham commented that Europe has many more occultation observers than the United States. Europe observers are closer together distance wise. They seem to have a more dedicated scientific mindset possibly due to the European sanctification of science in the curriculum of its educational system. Craig McManus has received emails from European observers asking how to access the password protected website for IOTA subscribers. Obviously this site containing ON is for paid IOTA members only. [But note – a similar site for IOTA/ES is being set up at _ HYPERLINK http://www.iota-es.de ].
Dunham mentioned sad news regarding Hans Bode. His wife, Heliga, recently died and Hans had been suffering from major health problems. Hans is one of the major drivers for IOTA’s European Section.
At 2:39 PM Dunham motioned to end the business meeting. It was unopposed.
Craig McManus had brought to the meeting his video system setup to record occultations and grazes. It consisted of an ASTROVID low light video camera, GPS unit, HORITA time inserter that inserts GPS times directly into the video (WWV is used as a check), and an image intensifier. An adapter allows the intensifier to be used on SCT telescopes. The system is also capable of recording latitude, longitude and altitude data simultaneously along with the GPS time.
The system can detect stars to magnitude +13 using a 10'' telescope, and +15 using the 20'' Obsession telescope. This impressive performance allows one to see very faint occultation stars, (and galaxies/nebula) in real time on video monitors which Craig mentioned was extremely useful for star parties. Instead of having one person at a time look through the eyepiece, many people could see a galaxy/nebula on the television monitor.
Craig McManus then showed a video of their first successful asteroid occultation of 911 Agamemnon from March 21, 2000. From their location they recorded a 14-second event.
The capabilities of this system were further shown when Craig and Terri did a Messier Marathon using a 10'' f/10 SCT. They were able to observe 105 out of the 110 Messier objects in a single night !!
Dr.Harry Bates reported on his successful observation of the occultation by 102 Miriam of the star ZC 1154 (SAO 97095) on February 15, 2000. His system consisted of an 8'' SCT, PC-23C video camera and WWV receiver. After driving to several locations to seek a hole in the clouds, he finally found an opening and the skies cleared up. He recorded an 8.36-second occultation and later digitized the tape and showed a graph. His digitized light curve of the event showed a possible short duration event prior to the occultation. Some speculation as to the nature of the event was discussed by the attendees but no conclusive explanation could be reached.
Richard Nugent showed his video of the Baily’s Beads from the August 11, 1999 solar eclipse. He traveled to Diyarbakir in the southeastern Turkey desert and met Paul Maley’s tour including Chuck Herald. Nugent and Herald navigated using a GPS receiver on loan from Trimble Navigation to find a particular rock identified by Paul Maley 6 months prior on a site survey expedition. He found the rock and set up using his highly portable system - 4'' Meade 2045D SCT, video camera, Sharp Viewcam camcorder model VL-E650 with built in 3'' viewing screen and speaker, and WWV receiver with direct feed into the camcorder. Nugent was stationed just inside the southern umbral eclipse limit under clear deep blue skies. The video clearly showed the dozens of Baily’s Beads progressing along the Sun’s limb over a period of about 2 minutes. Nugent had experienced about 16 seconds of totality at his location. Prior to the start of 1st contact, the temperature was measured at 105(F. After mid-eclipse, the temperature had dropped to around 95(F with a light breeze. Chuck Herald was stationed about 1 kilometer north but had problems with his filter and could not obtain useful video data. Nugent collected several thousand GPS data points using the Trimble Navigation GPS unit on loan at each site. The data was analyzed later by Paul Maley and accurate coordinates were obtained.
David Dunham showed a graph of the calculated lunar diameter from the graze of ZC646 from the lunar eclipse of November 29, 1993. Paul Maley, Chuck Herald and Richard Nugent observed from Baja, Mexico and several brave observers from Canada fought bitterly cold conditions approaching -28( C to observe the graze of the same star. The Maley/Nugent/Herald data fit reasonably well with the Watts charts but the Canadian team’s data didn’t match existing Watts charts well. Thus an average lunar polar diameter calculation will be difficult, but Dunham will try and publish the results in a future ON.
Bob Sandy presented the results from the spectacular grazing occultation of Aldebaran from April 19, 1999. There were 10 expeditions with 38 observers and 122 events were timed. Additional timings were made of “flashes”, or faint dimmings due to Aldebaran’s large angular size (0.033'') Sandy showed the video he obtained then Kiowa, Colorado expedition and the graze profiles from Utah and Colorado. The large number of events have added much useful data to the lunar limb profile database.
Sandy also showed the graze profile of ZC 2892 from November 14, 1999 observed by members of the Astronomical Society of Kansas City. The profile showed an unusual slope at Watts angle of 176(. This strange slope was confirmed by a Japanese team observing the graze of 44 Capricorni at a different libration angle.
Sandy then showed a video of the occultation of ZC 1276 taken just 4 days before the IOTA meeting (June 6, 2000) from a light polluted trailer park. The video showed 3 total occultations by the crescent moon and a star with apparent magnitude m = +9.7.
Daniel Falla suggested having a “clickable” map on IOTA ‘s website for new occultation observers. The location sensitive “click” would then display information on a particular occultation. Dunham commented that maps are published in Sky and Telescope for important events with contour lines showing occultation/graze limits. Readers can then interpolate to get data for their particular location. In addition Dunham said detailed times are posted regularly on IOTA’s website for most North American cities.
Hal Povenmire described his graze/occultation work and how he decides to reduce submit grazing occultation events from expeditions he leads. In 37 ½ years in chasing grazes, Povenmire has over 350 successful grazes plus many more failed ones. He has 40 grazes with questionable data that has not been reported. Hal has on average attempted about 70 grazes per year. Why is Hal Povenmire so successful? Is it the good weather in Florida? According to Hal, to ensure that a lot of grazes are successful, he has maps extending way out on the graze lines.
Povenmire told the group what the last 37 ½ years have cost him: 23 tape recorders, 16 time signal cubes, 300,000 miles on vehicles, $43,000-$44,000 plus 1 wife. In 1968 Hal had the option of attending his graduation to get a Master’s Degree or go to a graze. HE DID THE GRAZE AND GOT 6 EVENTS ! Hal told a few of his most memorable stories (too many to list in the minutes) and asked for IOTA member’s experiences for a possible future edition of his Graze Observer’s Handbook.
At 5:00 PM, the meeting broke to rejoin the Mid-Con talk on asteroid astrometry given by Brian Warner and Richard Davis.
At 6:30 PM a Banquet was held in a nearby hotel. A dinner with a few speeches plus some attractive door prizes rounded out the evening.
Sunday, June 11, 2000
The IOTA meeting continued at 9:45 AM with a group photo. David Dunham then showed the reduced asteroid profile shapes from Saturday’s video shown at the Mid-Con meeting.
Plans for some future asteroid events were discussed:
142 Polana - July 1, 2000, Central Florida to Central Texas, (m = 1.7, TYCHO star m= +11.1
481 Emita - July 3, 2000, Virginia to southern California, (m = 2.7, star m = +10.9. The star being occulted is not on the HIPPARCOS or TYCHO system thus larger path errors can be expected in the predictions.
111 Ate - July 7, 2000, Louisiana, Texas gulf coast, central Mexico, (m = 3.8, TYCHO star m = +9.4
142 Polana - July 11, 2000, Central Florida to central Texas, (m = 3.8, TYCHO star m = +9.1
309 Fraternitas - July 20, 2000, Nebraska to Georgia, (m = 4.7, TYCHO star m = +10.5.
Several predictions for 2001:
238 Hypata, March 6, 2001, (m = 3.2, HIPPARCOS star being occulted m = +9.5, gibbous moon 20 degrees away.
97 Klotho - May 25, 2001, (m = 6.5, HIPPARCOS star m = +6.5, crescent moon on opposite horizon.
447 Valentine, August 18, 2001. This asteroid is near a stationary poiint in its orbit, and some very fortunate observers in Antarctica will have a 3,270 second occultation !!! [Unfortunately, an update of Valentine’s orbit since then shows that this path will miss the Earth’s surface.]
9 Metis, September 7, 2001, Northwest US - California to Winnipeg, (m = 4.8, HIPPARCOS star m = +6.07, a possible naked eye event.
TYCHO - 2 CATALOGUE - released on February 8, 2000. This new important catalogue contains positions, proper motions and two color photometry for the 2.5 million brightest stars in the sky. The positions and the magnitudes were obtained with a new reduction of the original observations from the Tycho experiment on the ESA HIPPARCOS satellite and have a stated epoch of 1991.5. The stars have been reduced to the J2000 reference frame define by the HIPPARCOS catalogue. The proper motions in TYCHO-2 are probably the most accurate attainable in modern day astrometry - by direct comparison from the older positions of the Astrographic Catalogue (average epoch 1909) and more than 143 ground based catalogues, all brought to the HIPPARCOS based system.
The average density of stars is about twice that of the ACT catalogue. It is thus more likely that TYCHO-2 catalogue stars would be occulted by asteroids providing high accuracy in predicting ground paths of these highly location sensitive events.
Wayne Warren mentioned that are problems with double stars in the TYCHO-2 catalogue. Double stars with separations of less than 0.8'' have been thrown out since they could not be resolved. Errors in closer doubles are due to the fact that they are treated as “blended”.
Bob Sandy asked about the faintest limiting magnitude of HIPPARCOS. Warren said the catalogue is complete to m = +7, accurate to 1 or 2 milliarcseconds (0.001''), and Tycho - 2 catalogue complete to m = +11.5, accurate to 7 milliarcseconds (0.007''). TYCHO-2 proper motions are accurate to 2.5 milliarcseconds/year (0.0025''/yr).
Dunham remarked that both the Tycho and Hipparcos catalogues were produced by the spinning HIPPARCOS satellite. Star positions are highly accurate made relative to each other and are not directly on the system relative to Earth’s equator (but have been referenced to it via objects also observed with radio telescopes).
Dunham showed charts from the RASC Observer’s Handbook for upcoming grazes from July - December 2000 and preliminary plans were considered for select events passing near the location of the attendees.
It was mentioned that the duties of time insertion of video tapes was recently handed over to Rick Frankenberger of San Antonio. This job was previously handled by long time IOTA member Don Stockbauer. In addition, Derald Nye is still doing time insertion of video tapes in the Arizona area. Wayne Warren mentioned that Tom Campbell has a time insertion system that is currently not being used [Tom recently sent it to Wayne].
This prompted a discussion about methods to perform time insertion of video tapes quickly and inexpensively. Video time insertion allows the extraction of data to about 0.03 second at a 30 frame/second recording playback rate. The Stockbauer system uses WWV tones to trigger the time insertion. Dunham showed a new system on a schematic diagram using the GHS clock designed by T. Hayamizu of Japan. At a estimated cost of $200 it uses a flashing light to trigger the time insertion. Suggestions are needed for new techniques to simplify the time insertion process since it is critical for occultation timings.
Walt “Rob” Robinson updated the attendees on IOTA’s websites. Started in 1995, they are averaging 20,000 hits per year with over 90,000 hits since start up. Some 30 megabytes of space are currently available. Overall the websites are very successful for disseminating IOTA news and information about grazes, occultations, specific and general purpose articles and techniques.
Richard Nugent shared a tip on attaining fainter stars on video for observers who do not have image intensifiers. He had a short video adapter made at a local machine shop to connect his video camera to the back of his 4'' Meade 2045D SCT telescope. The adapter placed the CCD chip about 2 inches closer to the focal plane of the telescope. This has resulted in a decreased f ratio thus a larger field of view. With a larger field of view, fewer pixels are used to display a star image thus they are brighter. The limiting magnitude for his 4'' telescope system from his light polluted backyard in Houston city limits is m=+8.5.
Nugent brought up an issue suggested by Paul Maley - that adequate coverage be obtained at the northern and southern umbral eclipse limits for the next 4 solar eclipses.
At 11:40 AM the meeting was adjourned and David Dunham showed some videos of additional grazes/occultations. Dunham suggested that he might try and digitize some of the spectacular grazes and asteroid occultations to produce a video tape of high quality that can be used by IOTA members for talks and presentations.
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.