The International Occultation Timing Association's 32nd Annual Meeting
July 12-13, 2014
by Richard Nugent, Executive Secretary
David & Joan Dunham's back yard at the BBQ dinner
Garage sale items at UMD Observatory - glass plates, books, etc.
Chad Ellington presents IOTA business report
Homer F. Daboll award given to Brian Loader
David E. Laird award given to Gordon Taylor
20" Cassegrain and Celestron 14" telescope at UMD Observatory
UMD Observatory's 7" and 6" refractors
Hart Gillespie from Randolph College shows his occultation results
John Menke presented his case on Io's atmosphere
32nd annual meeting of the International Occultation Timing Association was
held Saturday and Sunday July 12-13, 2014 at the
meeting location was kindly hosted by Elizabeth Warner, Director of the
YouTube videos of the meeting are located here:
The people participating in the meeting in person and via internet conference:
On site attendees: President Steve Preston, Executive Secretary Richard Nugent, Secretary/Treasurer Chad Ellington, Drs. David and Joan Dunham, Bruce & Dylan Holenstein, Ted Blank, Dr. Terry Redding, Steve Conard, Dr. Wayne Warren Jr., Jay Miller, Barton Billard, Tony Mallama, Andrew Scheck, Dan Costanzo, Glenn Ward, Steve Tzikas, Michael Chesnes, Hartzel Gillispie, John Menke, Michael Chesnes, John Brooks.
Video Internet Conference Attendees: Bob Sandy, Chris Douglass, Walt Robinson, Dennis Rowley, Derek Breit, Ernie Iverson, Jack Gross, Jan Manek, Jerry B., John G., Kevin Green, Scotty Degenhardt, Steve Messner, Ted Swift, Tony George, Brad Timerson, Daniel Schultz, Gerhard Dangl, Jerry Bardecker, John Talbot, Mary West, Dave Herald, Hristo Pavlov, Brian Loader, Graham Blow.
9:00AM – Meeting start – Introductions
Preston opened the meeting and
welcomed everyone to the
Treasurer Chad Ellington presented IOTA’s membership status. Currently there
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: $6,038.02 2013, Oct 3
Ending Balance: $7,544.48 2014, (Includes funds donated for a special
asteroid satellite award)
Net Increase in Balance: $ 1,506.46
The breakdown of this past year’s budget is:
Membership Income: $600
Interest: $ ?
IOTA-VTI Royalties: $528
PayPal Balance: $2128.19...but
back and forth to the bank account and to IOTA-ES
-Web Service: Still Donated
-Awards: $ Not paid for 2 years
-Fees: $55.28 (Paypal)
The typical JOA costs are: Layout/design-$275, 45 copies printed-$202.83, envelopes/labels/printing-$42.38, postage-108.58. The most recent JOA issue cost $628.79 and with 45 issues mailed, cost was $15.72 each. But the price paid per issue by members depends upon several factors (location, payment & delivery options) but is approximately $10.25.
Paul Maley proposed (presented by Richard Nugent) IOTA’s new Asteroid Satellite Award. Called the MADASO (Merline Award for Discovery of Asteroid Satellite by Occultation), it is named for W. J. Merline of the Southwest Research Institute (SWRI). This one time award will be a $3,000 cash award plus a Certificate to an IOTA member(s) that discover(s) an asteroid satellite that can be confirmed. A partial list of the eligibility requirements of the award include that the discoverer be an IOTA member (anywhere worldwide), be an amateur using IOTA methodology (preferably the multi-station technique), not use equipment by another organization unless the equipment was given to IOTA plus the discovery can be retroactive. A list of confirmation procedures includes a review by IOTA Officers with confirmation being required by another independent technique such as radar, adaptive optics, satellite observation, light curves, etc. A validation panel would submit the discovery and confirmation to the International Astronomical Union (IAU) for an official confirmation and acceptance before the cash and certificates are awarded. The details of this award and validation process can change at any time. Further details will be available on a dedicated web page maintained by Paul Maley.
Richard Nugent presented Paul Maley’s Science Priority Asteroid Occultation
Topics 2014/2015. This is the continuation of a relationship between SWRI and
IOTA in which SWRI seeks observers and partially funds domestic
question from the meeting was would an observer that traveled to
Planned 2014 events include Nov 20, 3 Juno HIP 4437 (m = 7.0), 27 sec duration.
Dec 13, 35 Leukothea TYC 2443-00471, m=9.3, 9 sec duration.
2015 events: Jan 11, 2015: 1333 Cevenola, April 2, 2015: 90 Antiope, Aug 23, 2015: 107 Camilla. Low priority events for 2015 are Jan 26: Semele, Apr 4: Prokone, Sep 9: Nausikaa, Sep 13: Vanadis, Oct 30: Palatia.
President Steve Preston presented plans for the 2015 meeting. He showed 4 asteroid events that were possible candidates:
2015 Sep 4, (409) Aspasia,
Star: TYC 1846-2126-1 (mag 10.9), uncertainty is 0.27 path widths Path: From
Minnesota to the Bay area of
2015 Oct 17, (215) Oenone,
Star: HIP 1783 (mag 9.0), uncertainty: 0.69 path width, Path:
2015 Oct 30, (415) Palatia,
Star: HIP 100951 (mag 8.2), uncertainty: 0.47 path widths, Path:
None of these dates coincide with a meeting of any other astronomical society. The decision of which date to pick will be decided at a later date.
This year’s presentation of the annual Homer F. DaBoll award and David E. Laird award was made by the Award Committee Chair Dr. Terry Redding. The Homer F. DaBoll award is given annually to an individual in recognition of significant contributions to Occultation Science. “Occultation Science” is limited to actual IOTA research: total and grazing occultations, asteroid occultations and solar eclipses. 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 (
Previous David E. Laird
awardees: 2013 Hal Povenmire from
This year’s Award Committee
consisted of all past recipients (above), Dr. Terry Redding (
The 2014 Homer
F. DaBoll award recipient was Brian
In the same year
• He instituted the Jovian Satellite Eclipse program which he then coordinated for more than 20 years.
• He promoted and coordinated observations of the mutual events of the Galilean satellites across multiple seasons.
• He initiated and continues to coordinate the double star program for the determination of true separations and PA's from geographically separate occultation observations. Observers from around the globe contribute to this program, which has resulted in a string of publications, including a number in the JDSO.
Brian continues to be one of
the top observers of lunar occultations worldwide, as he has been for the
observation of minor planet occultations within the Australasian region since
predictions first became available. In (2010) Brian reported on 46 events. John
Talbot noted, Brian has also been a regional coordinator and reducer for total
occultations for many years, a role which has required him to interact with and
provide advice to almost every new observer in this part of the world. Together
with his wife Pauline, Brian has for many years prepared and published annual
summaries of upcoming bright total and grazing occultations for all of
The 2013 David E. Laird went to Gordon E. Taylor for being the father of asteroidal occultations, for his role in predictions for both Lunar and planetary events, and truly pioneering occultation work since the 1950's.
Besides occultations by
Tony George presented “Double Stars Discovered by IOTA Asteroidal Occultations published in the JDSO” (JDSO = Journal of Double Star Observations). Four new double star discoveries were reported and published in the JDSO since July 2013. They are:
Event Date Asteroid Target Star Separation (mas) PA (deg)
2013 Aug 15 611 Valeria UCAC2 30429828 380 ± 1.0 237 ± 3
2013 Feb 6 92 Undina TYC 1950-00148-1 28.4 ± 0.5 12.3 ± 2
2013 Aug 15 481 Emita TYC 7444-01434-1 31 ±10.0 235 ± 10
2013 Dec 28 141 Lumen TYC 1950-02320-1 152.9 ±0.8 105.8 ± 0.7
Valeria, Undina and Emita events occurred over Australia/New Zealand and the
Lumen event over
Wayne Warren asked is there are any procedures to add these new discovered doubles to the USNO's WDS catalog. Dunham replied that Brain Mason (USNO) picks them up once published in the JDSO, there they are placed into the interferometric catalog.
Tony George next presented the R-OTE version 3.2.8. (Occultation Timing Extractor) developed by him and Bob Anderson. The major revisions of R-OTE since last year are that it allows direct reading of Limovie and Tangra files without modification, allows loading and processing of a secondary light curve for comparison and normalization, performs time stamp error checking and validation of event frames and reports all solutions in both readings and date/time format. It also interpolates Tangra blank-cell data to allow complete processing of Tangra files, automatically subtracts Tangra background values from raw light curve data to allow proper magnitude drop processing, and implements integer-frame or sub-frame timing algorithms based on AIC statistical analysis. He showed some light curves and how R-OTE used the maximum likelihood estimator (MLE) and Akaike Information Criterion (AIC) for light curve fit and model selection. Examples were also shown on how R-OTE uses advanced methods to deal with noise and SNR issues.
David Dunham presented basics of observing and timing
occultations. He described his first graze predictions and attempted
But the situation changed
after Dunham took a course in solid geometry at the
On April 10, 1962 the 2nd
graze he attempted, 64 Ori, m = 5.2, was predicted for nearby
On September 18, 1962 Dunham
made predictions of the graze of 5 Tau, m = 4.3. His predictions showed
the graze path about 40 miles north of
For the graze on
October 8, 1963 of ζ Tauri, Dunham had published the prediction in the October,
1963 Sky and Telescope issue. It is interesting to note that in 1963, Sky
and Telescope had been publishing the yearly occultation supplement for
standard stations for 5 years, but this was the first map published of a
grazing occultation and suggesting that these events be observed. It was
Dunham showed photos of video setups with various telescopes and the necessary equipment and adapters needed. Photos included Richard Nugent's air carry on system and Scotty Degenhardt's "Mighty Mini" systems.
Dunham closed the talk by
showing a few video images he obtained of the first ever recorded lunar meteor
impacts from November 18, 1999. These video images would have not been noticed
without Brian Cudnick's first ever visual observation of an impact from
Elizabeth Warner next presented the history, current research, and outreach of the University of Maryland (UMD) observatory. Constructed in 1963-64, the UMD was initially seen as an important component of the teaching and research program in the Department of Astronomy. Public programs were started almost immediately to bring the excitement of astronomy to the University community and the general public. Although the growing lights of the DC Metro area have made serious research more difficult at the UMD Observatory, the facilities continue to play an important role in the education and outreach of the Astronomy Department. Telescopes and equipment includes: 20″ Bent Eichner Cassegrain, 8″ NASA Astrograph, 7″ Astro Physics refractor, 14″ Celestron SCT, Elizabeth's personal 6″ Astro Physics refractor, Six 8″ Celestron Ultima 2000s setup on piers outside of lecture hall, visible light and solar prominence filters. There are several portable scopes: Six 8″ Celestron SCTs, 10″ dob, 90mm refractor, and a 4″ Newtonian.
The 20" Cassegrain was refurbished in 1999-2000, has a custom control from Astro-Physics and an Apogee 6 CCD camera with a 1024x1024 array and a 5-cell filter wheel. The 8" NASA Astrograph is a MOTS ‘Spy’ telescope is on permanent loan from GSFC. It uses a "yank-n-point" method for pointing with a counter-weight driven drive with a recently replaced cable.
Research areas previously in the past had deterrents due to light pollution and outdated equipment. Exoplanet transits were made in the summer 2011 using 152mm refractor and summer 2012 using both refractors. In the 2012 LPI meeting, data obtained from the UMD observatory was published in a paper: "Physical and orbital properties of the (22) Kalliope system from mutual eclipse observations". Research is done by high school and college students in the following areas: Exoplanets, supernovae searches, asteroids/comets, Jovian moons and events, occultations, software and astrophotography. For occultations, a ADVS video camera was purchased in 2013.
The observatory also teaches classes and for nearly 45 years has regular open houses on the 5th and 20th of each month. Group tours are on the 5th and 20th of each month BEFORE public session of Open House. Scouts, school classes, retirement home groups and home schooled students can tour the observatory.
Funding: Funding comes out
of the Astronomy department. Additional funding comes from student tech fees,
sales of used text books, ‘garage’ sales of old equipment, slides, photographic
glass plates, etc. The observatory has no paid advertising, it uses the web for
most announcements: web page, Twitter, Facebook and a 600+ emails list. Local
newspapers also publish articles about upcoming events. UMD is fortunate to
have speakers not only from the astronomy department (professors/grad students)
but also some of the local science institutions in the
UMD is on the web: www.astro.umd.edu/openhouse
----- Lunch break---------- During lunch, Ms. Warner gave the attendees a tour of the observatory facilities.
Dunham next presented basics of observing and timing asteroidal occultations. With grazes began to get going in the early 1960's, the 1964 publication of Watts’ charts gave us the possibility to predict the lunar profile for grazing occultations. Later in July 1975, IOTA was formed (mainly because Dunham couldn't keep up with mailing and printing costs for graze predictions). IOTA was formed primarily to promote the observations and analysis of lunar and grazing occultations.
In the 1990’s, Dunham
thought with the equipment is doing all the work, maybe he should be somewhere
else making another observation. For a graze of omicron Leonis on 1998 November
12, he set up a 5-in. clock-driven SCT at Delta,
For the 2001 Dec. 21 Grazing Occultation of 4.0-mag. t2 Aqr, 8 stations were set up by 4 observers. Later on
in 2007 came the 50mm Mighty Mini scope revolution designed and built by Scotty
Degenhardt followed by the 80mm Might Midi's. Dunham then talked about a few
grazing occultation attempts with remote stations: 3.5-mag. eta Geminorum in
Dunham was the first person to ever set up a remote station that successfully recorded an asteroid occultation on September 7, 2001 of 9 Metis. He set up a remote video camera on a tripod and drove to a second station. When he returned he saw the camcorder battery died, but after the occultation. Dunham showed several images of Scotty Deganhardt's remote 50mm Mighty Minis which revolutionized asteroid occultation observations. Scotty's first major attempt was in 2008 when he set up 11 stations...all misses but he had gaining valuable experience. Now Scotty has designed the Mighty Maxi - an Orion 120mm short tube refractor as a remote video station. Dunham showed screen shots of the powerful Occult Watcher (OW) software written by Hristo Pavlov. Using your lat/long coordinates, Occult watcher will notify you of asteroid events coming to within a user specified distance. Users can input their intent to observe at a specified offset from the path center and OW will place a telescope icon on your planned position.
Dunham mentioned Occult written by Dave Herald is the comprehensive program that predicts, displays plots and analyzes all types of lunar and asteroid occultations, star positions, double star data and eclipses. Despite the advances in video cameras and their sensitivity, he mentioned the additional use of CCD camera for drift scan observations of asteroid events.
Steve Conard (with Dylan Holenstein and Bruce Holenstien) presented Lessons learned from planning high-speed observations of the Regulus-Erigone occultation. They planned on using available EMCCD (electron multiplying CCD) cameras, supplemented with typical low light video cameras to: Detect the white dwarf companion of Regulus, attempt to measure the angular size of Regulus, and contribute to size and shape measurement of Erigone. The team originally was going to observe the event from several locations and later decide to observe from a single location in case a hardware or other problem came up. They were able to secure the observatory at the State University of New York (SUNY) at Oneonta to host the expedition.
SUNY-Oneonta has a well equipped observatory with a16″ Meade SCT (they planned a time inserted video) 14″ Celestron SCT in— they planned to use a 512B EMCCD tuned to detect the white dwarf companion, 1-m portable folded Newtonian on wheels—they planned to use a 128 EMCCD to measure angular size of Regulus. The team did advanced testing using Steve’s 14″ Celestron SCT by using Dave Herald’s suggested test of recording Regulus in the field, then slewing it out of the field as quickly as possible—to look for time for pixel recovery. A similar test was done using the Photometrics EMCCD 512x512 pixel camera. They used 167 frames per second. Brightness levels went from a peak pixel brightness of ~8,000 to not detectable in a single frame with an estimated SNR > 10.
The weather forecasts prior to the event looked dismal, but Dylan and Bruce decided to travel in any event. While there was some “sucker holes” in the area, there were none near Regulus at event time. With this experience, they plan to attempt future events such as high speed lunar occultations.
Ted Blank presented “Planning and Preparing for the Erigone-Regulus Occultation of March 2014”. The goal was to use every available method to contact as many people as possible in advance of the event, to make everyone in or near the path a stakeholder - potentially millions of people (millions of chords?), flood the market with accurate information about the event to outweigh the inevitable inaccurate information that would surface, use the opportunity to educate people about astronomy, the solar system, asteroids, occultations, the value of scientific measurements, IOTA and its missions and goals, and make it as easy as possible for everyone to participate and measure the event to their highest possible level of accuracy with a new smart phone timing app.
In January, 2014 Ted submitted an article to JOA entitled “Recruiting and Deploying a High-Density Public Observing Network for the 2014 Occultation of Regulus by (163) Erigone” The article showed how the public would be informed of the event and how they could participate. He showed snapshots of two YouTube videos Richard Nugent made ("big rock" and "shadow" versions) showing an animation of the event. In December 2013 a web site was created to describe the event and answer FAQs. In the March 2014 Sky and Telescope, Steve Preston published an article about the event. The website also showed where people need to go see it, how to find the correct star, and how to time the event with any way you they could (audio, stop watch, WWV, Video with VTI and app created for i-phones written Norbert Schmidt from the Netherlands. With missed observations made by visual observers, that would place potentially 100's-1,000's of observations at the edge of the occultation path placing a restraint on Erigone's size.
January 2014 Ted updated the Wikepedia page on the event. February 2014 Ted wrote a press release and sent it to all the information sources he could think off.
In January - February 2014 Hristo Pavlov made a web page to support observations made by people who had made any kind of observations timed or not. The page had a Google map in which people could click on where they observed from. Ted also made a Facebook page about the event which was very successful.
gave several talks to several astronomy clubs encouraging participation and
having them involve the public. Both Ted and Steve Preston were interviewed by
many newspapers. Even USA Today
published an article about the event. IOTA-ES observers Eberhard Bredner and
Konrad Guhl came from
Tony George presented Lessons from the DSLR campaign for the Erigone-Regulus event. DSLR Campaign Objectives were to use modern DSLR or video cameras to obtain as many additional “duration only” chords that can be fit to other timed chords so that the profile of Erigone can be better mapped out. For properly equipped DSLR observers they were to attempt absolute timing of the event by recording WWV audio signals on video or recording video of a VTI display of UT before and after the event recording. To maximize results, DSLR users were asked to pretest and make a 30-50 second video using a 1/30th second shutter speed (similar to video recording rate), use focal length of 75-300mm, focal ratio f/4.5-f/5.6, use highest ISO rating as possible and to use manual focus. Initial tests were done at 1600 ISO, 3200 ISO and 6400 ISO....the SNR was very high.
Amateur astronomer Andreas Gada from
presented "Asteroid Occultation Timing at
Hart has a $2,000 grant to obtain equipment. His occultation research could be extended to other colleges. Steve Conard was instrumental in getting Hart interested in occultations.
Ted Blank presented a summary of IOTA’s participation at the
Northeast Astronomy Forum (NEAF) 2014 in
John Mencke presented “On doing photometry with video cameras”. John says video software is not really suited for photometry and video cameras are not best suited for photometry but it can be done. Limovie and Tangra can both be used for photometry (Tangra is more sophisticated). John says video software is not designed for photometry-its hard to measure individual pixel values, hard to handle long blocks (hours) of data, hard to use comparison and reference stars and software is not real time. Video camera problems: they may be non-linear, they are not designed for non-point, mid-level brightness image issues, ADC may not handle stars properly, they have high readout noise, and have limited dynamic range.
John showed a JEE event and challenges and how saturation affected the results. He says to do successful photometry you need a linear camera, and photometric software such as MaximDL. Sources of error include non-linearity of the camera, saturation, unstable gain, noise, sky transparency (star altitude-extinction and color), color mismatch, dew. On the analysis front, an improper comparison stars and improper software will affect results.
These problems can be overcome with good software, and good record keeping. MaximDL and CCDsoft are suggested software packages to use. To use video, use VirtualDub to select 100 frames and convert them to JPG's. By video taping a star cluster, convert the video to JPG's, pick a few dozen stars, measure their intensity and plot the results. John suggested to get started with some easy variable stars, seek how-to-photometry books, and be skeptical of your work. And of course, peruse the AAVSO and MPO sites.
Dr. Terry Redding presented "Occultations: One perspective on knowledge
acquisition". Terry first got interested in astronomy by acquiring a
14" telescope and the book "The
Sky is Your Laboratory-Projects for Amateurs" by Bob Bucheim. Chapter
2 was about occultations. Terry learned from the Baja boys Kerry Coughlin* and
Roc Fleishman from
* It was learned just after the meeting that Kerry Coughlin had passed away a month prior to this meeting. Kerry had succesfully observed numerous asteroid occultations along with Roc Fleishman from Baja. He will be surely missed.
Ted Blank showed a custom PVC adapter to use with the Orion Go-Scope 80mm to obtain proper focus for a PC-164C camera. He showed the adapter, how to build it and gave a parts list available from most hardware stores. This Orion scope is half the price of the 80mm Mighty Midi's, has an easy pre-point mount and is painted black for easy concealment off road at unattended sites.
Dr. Ted Swift presented a talk about the PC165DNR camera’s characteristics and performance. This camera is a color integrating camera with controls for the various functions on the left side of the camera body. The camera has been available from Supercircuits.com few a few years and has these features and Controls
– Digital Noise Reduction (DNR; filters in space, time)
– On Screen Display (OSD)
– Row of five Directional buttons on side of camera (Enter, Up, Down, Left, Right)
Its chip size is 1/3", with a 600 TV line resolution (color) and 650 in b&w mode. Ted showed several test images of M67 using a 10" (24.5cm) f4.7 Newtonian. Using automatic gain control (AGC) modes of low, medium and high along with 2x - 256x integration, stars of m = +16 to m= +17 were visible. From the tests, it was clear the noise level was highest with AGC set to "high", so Ted recommended setting the AGC to "medium." With the control buttons on the camera's side, (this shakes the camera/telescope every time they are touched). Ted developed a simple hand paddle to operate the functions. This opened up the possibility of developing a computer control for this camera.
Ted’s recommendations are: Choose the shortest exposure time needed to get a “stable” star, but not less than 1/60 second. This maximizes time resolution. Use the explicit exposure settings (2x, 4x…) rather than unpredictable “Sense Up” setting. The gamma function appears to be fixed at 0.45 in the PC165DNR. A gamma correction can be applied in LiMovie, etc. (1/0.45 = 2.2) afterwards. Use AGC=medium, or AGC=high with care and set the PC165DNR to black & white mode.
Dylan Holenstein discussed specialized software and equipment for high-speed scientific cameras. The motivation was to develop software to control camera for high time resolution observations of transient & high cadence events with a high quantum efficiency (QE), low read noise and precise timing. He tested the EMCCD cameras such as the Photometrics Cascade 512B and the Watec and Supercircuits cameras used by many IOTA observers. The desired features of a software package were: full EMCCD camera feature control , live-view of the star while recording that wouldn’t tax the PC, ability to drive multiple cameras, the ability to record for long periods with precise timing, no data loss and be able to recover from equipment failures. After looking at several programs to drive the cameras, they decides to write their own software to get all the desired features in one package. Several tests were done using Tangra and the PC-164EX-2 on an LED of the blinking 1pps time signal. Dylan showed some slides of timing tests Regulus and the asteroid Hohenstenia (m = +12.8) and TYC5083-00898-1 (m = +10.7).
Elizabeth Warner presented UMD's
recently acquired Astronomical Digital Video-System ("ADVS") camera.
She did an undergraduate thesis on grazing occultations and it was logical as
the UMD Observatory Director to have a good video camera for occultation work
and to educate students on occultation science.
6:10PM, Saturday session ended. The meeting attendees gathered at the Dunham's house for a BBQ dinner.
SUNDAY July 13
Hristo Pavlov discussed the recent developments in Tangra 3 and the ADV file format. Tangra 3 was released at the time of the meeting. New Tangra 3 features include IOTA-VTI time stamping, new tracking engine, integration with Occult's AOTA software, Occult Watcher, mutual events reduction, overlapping objects fitting, 3D background support and light curve analysis.
For Tangra to read the IOTA-VTI time stamp, all fields and frames must be present. The new tracking algorithm is much faster than in version 2. Hristo has also added a color display mode. For reducing Jovian mutual events, he added a "measurement type". The user will specify either occultation or eclipse. Another feature was the use of a point spread function (PSF) to deal with close overlapping targets such as close double stars. This helps reduce the overlapping of the brightness contours.
Dave Herald presented an update to the AOTA software. The program handles D and R events independently and uses cross correlation analysis with uncertainties using a Monte Carlo routine with noise effects applied to light curves. AOTA is now a part of the Occult program. It creates an alternative tool to analyse asteroidal occultation light curves. Its focus is on measuring the D and R events independently. AOTA can handle Limovie & Tangra files, handle output from integrating cameras and has user friendliness & simplicity. An important feature of AOTA is that if no time stamps are available they can be set manually. Another reduction feature is that AOTA can identify a cloud moving in vs. a real occultation by overlaying a comparison star. The program can view and save measurement reports and save the plots to send to others. AOTA ha a detailed help file with step by step instructions along with guidance on interpreting the results.
Dave Herald then presented a
summary of worldwide occultation results in 2013. Asteroid occultation
observations worldwide have dropped in the past 3 years from a high of about
230 in 2010 to slightly less than 200 in 2012 and 2013. For the time period Jul
2012 to Aug 2013 the
Dave Herald then presented a summary of Jovian moon mutual events: occultations (not extinction events but rather occultations). A major benefit of observing a mutual event is that measuring /analysing the light curve leads to very precise measurements of the relative positions of the satellites. These can be used to improve our knowledge of the orbits, and long-term orbital variations. For the 2009 mutual event season: 370 events were ‘observable’, 172 different events were observed at 74 sites, and 457 light curves obtained and reduced.
The observing requirements to make these observations are: motor driven telescope (but need not be equatorial), time to 0.1 secs UTC – GPS, NTP**, WWVH, video with time stamp and a recorder – VCR, Computer Frame grabber – to convert to a .avi file for reduction purposes. The data can be reduced by Limovie or Tangra. Observations are reported to IMCCE (effectively, Paris Observatory). A simple text report (standard form) is submitted with attached .csv and optional plot.
Some observing issues he mentioned: the video needs to be compressed when creating the avi file – otherwise the file will be HUGE, plus concerns about linearity of the video camera. Where possible, make sure the Gamma is set to 1. Regarding image motion – minimise. In particular, any vignetting across the field will cause light variations if there is significant image movement. The IMCCE recommends the use of a red filter – reduce sky background. Closeness of the satellites to Jupiter can create problems with correcting for sky background, which will have a 2nd-order variation with distance from Jupiter. Aperture sizes and shapes can affect the measurement result. On this note, Hristo has improved Tangra to model the glare from Jupiter, to improve background subtraction.
Herald showed some sample light curves of events (both good and bad) and what to watch out for. He also plotted the time differences between IMCEE vs. Occult predictions. Most are within 30 secs and as expected, large time differences are associated with long duration events over 500 sec.
The IMCCE has a dedicated web page at: http://www.imcce.fr/phemu/ Herald showed a listing of the remaining events for 2014.
Tony Mallama presented his analysis of occultations of the Galilean satellites: How accurate are the ephemerides? The source of the Galilean ephemerides comes from JPL JUP-series (includes astrometry from Galileo Orbiter), IMCCE (Paris) L-series, (omits astrometry from Galileo Orbiter) and the JPL E-series (1990s vintage).Tony analyzed 20 years of Jovian eclipse timings, computed observed-minus-calculated (O-C), and searched for anomalies in O-C plots. He showed slides of O-C errors and resonance errors for Io and Europa. The O-C oscillations showed a 1.3 year period for Io, Europa and Ganymede.
The astrometric accuracy includes random photometric errors (scatter-assumed zero) and systematic (modeling) errors. A paper by Emelyanov 2009 MNRAS 394, 1037-1044 estimates the astrometric errors both random and systematic to be in the 0.03"-0.04" range. The comparison between uncertainties of ephemerides and astrometry indicated a worst case for JUP230 = 0.004 arc second best case for astrometry = 0.044 arc second. He showed graphical comparisons of the astrometric uncertainty vs. ephemeris uncertainty. The bottom line was that JUP230 is 10x more accurate than mutual occultation astrometry.
John Mencke presented a review of claims for an extended Io atmosphere proposed by Scotty Deganhardt. In this study, John looked at the JEE (Jovian Extinction Event) papers by Deganhardt from 2010 and 2013. The main issue John looked at was the "wings" that appear in the JEE plots that Scotty has published which appear to indicate an atmosphere around Io. The critical problems around this claim according to John is that the professional astronomers see no thick atmosphere, the Jovian eclipses show no wings and duplicate observations show null results.
The pro astronomers see no thick atmosphere. Their data indicates: telescopic searches with large telescopes and HST have never imaged an atmosphere, Advanced spectroscopic searches with large telescopes show only very faint (1/109) atmospheres, satellite probes near Jupiter see nothing, satellites within 200km of Io saw/felt none and would literally have slowed down or burned up. Plus (Menke postulate) an extended JEE atmosphere is not gravitationally feasible.
Eclipse observations show no wings although they should. Io’s atmosphere should cast shadow during an eclipse, but none is seen. Another issue is that duplicate observations don't show the wings. John did a detailed analysis of what the wings might represent. This due since the atmosphere they indicate could not be confirmed by the professionals nor by others observing Jovian events.
So if they are not real, what could they be ? On John's request, Scotty sent him 17 DVD's of the AVI files that showed the wings. John analyzed the videos using photometric methods since he has previously stated that Limovie is not the best way to analyze these long videos. He ruled out that the wings are processing artifacts. He looked at saturation and linearity effects. His postulated that saturation is a plausible cause of the wings. This due to his experiments studying the saturation effects. His result—saturation dims intensity 10-14% .... the same as wings.
John pointed out that some JEE group occultation videos show no wings (PDE, etc given as cause). Examining the video data shows they were taken with longer focal length scopes-giving larger images, lower pixel values leading to no saturation.
His conclusions indicate 3 critical problems w/JEE: astronomic data, eclipses, and other observers show null results, plus the root problem-insufficient attention to the camera sensor,
and failure to use photometric methods in the reduction. Thus John concludes that the interpretation of data is incorrect: there is no thick Io atmosphere.
William Hanna (through a pre-recorded audio file) presented an interesting occultation observation: Deimos, a satellite of Mars occulted HIP 62565. John Broughton, a prolific occultation observer based in Queensland, was examining upcoming predictions made by Occult 4 and found that a narrow (~12 km) predicted path for (II) Deimos, not currently listed in an OW feed, would pass just to the south of Alice Springs. John sent Hanna an e-mail (giving barely four hours notice) and he immediately set up under ideal observing conditions. He observed a 1.5-second (of a possible 1.8-sec) occultation. The accuracy of the prediction was no doubt due in large part to the fact that the target star was in the Hipparcos catalog.
Hanna showed the ground path of the event, the plot from Tangra showing the clear disappearance and the video he acquired. He also showed the result of his successful observation of the occultation of 28978) Ixion on June 24, 2014. He showed the Tangra plot of the event along with the video frames showing the "D" and "R". Hanna also described his equipment setup whch includes a Meade 8" LX-90, the ADVS video system (he's a beta tester) and a Point Grey Research Grasshopper EX camera.
presented Results of recent grazing occultation observations. David started
with the graze expedition of m Arietis on 2007 June 12 north of
Dunham's first success on a
graze with remote stations was the occultation of 3.5-mag. eta Geminorum in
The next graze attempted with
remote stations was of 4.9-mag. w2 Tauri (ZC 628) over
Dunham summarized that grazes are still useful for proper motion studies, and for resolving close doubles better than total occultations (due to grazing geometry, & multiple PA’s), grazes provide good practice for mobile observation, a capability valuable for increasing the number of positive asteroidal occultations.
David Dunham next talk was on "Asteroid Occultations from Remote Stations". Dunham described how the remote video station method works for observing asteroid occultations. He showed Scotty Deganhardt's 50mm Might Mini system, the 80mm Orion short tube Mighty Midi system, the Might Maxi system mount and the programmable remotes for doing the timed recordings. He the showed some asteroid profiles obtained with the remote stations: 135 Hertha from Dec 11, 2008, 695 Bella, from Aug 31, 2010, the binary asteroid 90 Antiope from July 19, 2011, 91 Agamemnon Jan 19, 2012 - of which a possible asteroid satellite was detected by Steve Conard, 617 Patroclus Oct 21, 2013 - observations and sky plane plot show satellite 0.24" away in PA = 265 deg, 1 Ceres Oct 25, 2013, and a first ever occultation and profile for 788 Hohensteina on July 8, 2014 1 week before this meeting.
Scotty Degenhardt presented his continued research on Jovian extinction events: “Update and call for Observations”. There have been claims against his JEE work asserting the wings and Io’s atmosphere are non-existent. He started by showing the Galileo probe had found 600nm particles around Io. He presented a case for why the Hubble Space Telescope (HST) doesn’t see Io’s atmosphere when it transits. He said a main issue is that the HST filter only samples 500nm or shorter wavelength particles. These are narrow band filters so the expected extinction detection would realistically be a fraction of the total broadband extinction. The HST images he showed plus luminosity graphs illustrated this concept.
Another issue is mutual event data submitted to the IMCEE. The Mar 28, 2003, Apr 21, 2003 and Sep 1, 2009 Io events began to show the JEE wings however the graphs didn’t have enough data. The typical data set submitted to IMCEE is 6 – 10 minutes in length. Scotty has shown that typical JEE measurements are tens of minutes in length thus the IMCEE data missed it due to the short durations of photometry.
Another claim he responded to was, “The 1971 occultation of Beta Scorpii C by Io showed no extinction trend. Therefore JEE can’t be real. The light curve of this occultation shown covered just 30 seconds of ingress and clearly showed the occultation but this was only 0.2 Io radii. Scotty stated that in order to begin to see the full extinction of the wings, one would need to record of 21 minutes prior to the event thus this argument doesn’t make a case against the existence of JEE’s.
Another claim against JEE’s was that “Video cannot provide accurate photometry.” He showed video data vs. CCD data of an exoplanet transit of HD189733 b. The video light curve clearly had less noise and a higher S/N ratio. He also stated that due to the sheer volume of video data vs. CCD data that video wins at photometry by greatly leveraging the statistics to increase the S/N.
On the assertion that video data can’t be calibrated, Scotty showed before and after light curves of Saturn’s glare. Following calibration from a raw video, this light curve showed that the intensity response was flattened. On the assertion that glare from Jupiter makes it impossible to get accurate photometry. Scotty showed a Limovie aperture ring 20 arc-seconds from Jupiter and how its light intensities were nearly zero on a Limovie graph compared to the Moons, hence the glare was virtually non-existent.
Another assertion was that “gamma was the source of the JEE trend is their light curves.” Scotty showed a light curves with gammas of 1.0 and 0.45 and both showed the JEE dimming.
Another assertion is that “camera response from merging intensities (saturation) causes the JEE trends.” Scotty showed an extinction light curve from Sep 1, 2009 (IoII) before and after the saturation effect was removed. Even after removing the saturation effect, the JEE trend is still prominent. He arrowed where the saturation starts and ends. From two different reduction techniques data from Terry Redding’s video of the Nov 1 2009 Europa/Io transfit matches the JEE extinction trend.
Scotty referred to papers
published by professional astronomers in Nature for Mar 21, 1996 in which
Scotty then showed some slides on how best to observe for those who wish to help him in his JEE campaign. His predictions, results and discussions are available at:
JEE Yahoo discussion group: JEE_Talkemail@example.com
Scotty’s last 2 slides showed a long list of references supporting his points.
presented Grazing opportunities for late 2014 and for 2015. For this talk, he
showed graze maps across
David Dunham next presented the upcoming lunar occultation
of Venus by the 15% waning Moon, and the opportunity to observe for the Ashen
light. The event occurs on 2015 Oct 8
David Dunham presented
Upcoming asteroidal occultation events for late 2014 and for 2015 over the
3237 Victorplatt Jul 20, 2014
1650 Nuwa Jul 26, 2014
5534 1941 UN Aug 1 2014
2711 Alexsandrov Aug 21 2014
93 Minerva Sep 6 2014
Rhea (Saturn's Moon) Sep 13 2014
261 Prymno Sep 15 2014
247 Eukrate Oct 28 2014
1268 Lybia Oct 28 2014
3 Juno Nov 20 2014 (SWRI event)
35 Leukothea Dec 13 2014 (SWRI event)
1333 Cavenola Jan 11 2015 (SWRI event-asteroid might be binary)
72 Feronia Mar 5 2015
216 Kleopatra Mar 16 2015 (may have 2 satellites)
90 Antiope Apr 2 2015 (SWRI event, binary asteroid)
10199 Chariklo Apr 4 2015 (asteroid has newly discovered rings)
194 Prokne Apr 4 2015 (SWRI low priority event)
2 Pallas Apr 14 2015
107 Camilla Aug 23, 2015 (SWRI event, binary asteroid)
16 Psyche Aug 28 2015
112 Iphigenia Sep 3 2015 (large angular diameter star)
409 Aspasia Sep 4 2015
192 Nausikaa Sep 9 2015 (SWRI low priority event)
240 Vanadis Sep 13 2015 (SWRI low priority event)
215 Oenone Oct 17 2015 IOTA meeting candidate
415 Palatia Oct 30 2015 IOTA meeting candidate
David Dunham then presented
the future occultation of Regulus by 1669 Dagmar, 2015 May 24. The path starts out over the
(presented by Richard Nugent) gave the IOTA-VTI update. IOTA has the rights to
the IOTA-video time inserter. It’s manufactured by Video Timers (
then presented plans for the 2017 North American total eclipse of the Sun. He briefly described the attempt in May 2012
to observe the Baily's beads in
Nugent described how the observations should be made. All observers would use a 75mm-100mm aperture telescope, the Baader solar filter, use one of two narrow band filters and use either the PC-164C or Watec 902H cameras with time inserted video. The narrow band filters are the Wratten #23a and #56 that match the SODISM wavelengths of 535nm and 607.1nm. Plans are to have 4 stations, two at each northern and southern limit using all combinations of the narrow band filters. Some discussion was made on the reduction techniques that will be used for the solar radius.
David Dunham then discussed Erato event plans for early Tuesday morning. Weather prospects did not look good at meeting time. The nearly full Moon will be just 13 deg away from the target star. Dunham showed pre-point charts and offered black paper to use as dew shields for potential observers.
The meeting ended at 5:55 PM.
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.