The
International Occultation Timing Association's 40th Annual
Meeting
August 13 -14,
2022 via Zoom online
by Richard Nugent, IOTA Executive Secretary
The meeting presentations, Zoom link agenda and schedule for this year are located here:
http://occultations.org/community/meetingsconferences/na/2022-iota-annual-meeting/
Homer F. Daboll Award: Fumi Yoshida David E. Laird Award: Marek Zawilski Lifetime Achievement Award: John Broughton
Attendees: The meeting started with a total of 65 participants and this number fluctuated slightly throughout the sessions.
August
13, 2022 20:00 UT – Meeting start
Vice President Dr. Roger Venable opened and welcomed everyone to the meeting.
Treasurer Dr. Joan Dunham presented IOTA’s
financials and membership status. A summary of the year’s
income/expense report (July, 2021 to July, 2022):
Income:
Expenses:
NET Income: $13,242.33
Cash donations wewre received from Walter Morgan, Richard Nugent, Berton Stevens and Don Stockbauer.
Non-cash donations were made by many, spending many hours on observing activities, data analysis, software development and maintenance, IOTA administration, outreach activities, web site maintenance, and more. To everyone who donated to IOTA this past year: THANK YOU! Your support is key to IOTA’s success!
IOTA's original by-laws were created in 1983 and do not reflect today's operations. New By-laws have been created and circulated for review. A corrected version will be sent out the day after the August 15th meeting. The thirty-day (30) voting period will begin August 15, 2022. IOTA (dues paid) members should send their votes and comments to IOTAtreas@yahoo.com. The vote tabulation will be announced in a Zoom session planned for October 1, 2022 and to discuss the new by-laws and proposed changes.
IOTA Membership and Subscription:
Membership only -119
Affiliate membership - 4
Executive Secretary Richard Nugent
presented IOTA’s election results. Officer elections are
held every 3 years as per the by-laws. All current Officers
agreed to continue and the election was announced on the IOTA
list server with voting open from July 22- Aug 12, 2022. The
voting was unanimous and the Officers were re-elected into their
respective positions:
President: Steve Preston
Vice President: Roger Venable
Executive Secretary: Richard Nugent
Secretary & Treasurer:: Joan Dunham
V.P. for Grazing Occultation Services: Mitsuru Soma
V.P. for Planetary Occultation Services: John Moore
V.P. for Lunar Occultation Services: Walt "Rob"
Robinson
Director: David Dunham
Richard Nugent then presented IOTA’s Homer F. Daboll, David E. Laird and the Lifetime achievement awards. The Homer F. DaBoll Award is given to recognize significant contributions to the field of occultation science and to the work of IOTA. This year's recipient is Fumi Yoshida from Japan. Fumi Yoshida is the member of DESTINY+(Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon flyby and dust science) project with plans to observe 3200 Phaethon through spacecraft flyby mission by JAXA and PERC. Phaethon is the special active asteroid also known as the parent body of the Geminid meteor shower. Her team has made and will continue to make preliminary ground-based observations for 3200 Phaethon to ensure the success of the mission. Yoshida is in charge of these ground observations. In cooperation with NASA, SwRI and IOTA, she asked observers around the worldwide to observe occultations by 3200 Phaethon starting from 2018, and organized her own observation team composed of professional researchers and amateur observers. Right after that, the first successful observation was made. The fantastic 2019 July 29 result observed in the western USA was organized because of what her team requested to IOTA in North America. More efforts led by her have resulted in 9 successful occultations worldwide thru 2021 of small objects down to 6 km diameter in size. Among them, the occultation on Oct 3, 2021 in Japan was a great success, with 18 sites positive (7 sites miss, the other 11 sites failed) by a 36-site observing party led by her.
Fumi sent the following message upon her notification of
the award:
Dear Richard,
Thank you very much for the wonderful news. Mr.
Hayamizu gave me the details of the award, and I am truly honored
to receive this very prestigious award from IOTA. I am also
attaching a photo as requested in your previous e-mail. I would
like to thank the many amateur astronomers who helped me with the
Phaethon occultation observations. There were no professional
researchers around me who specialize in occultation observation,
so I finally succeeded in the observation while asking for help
from amateurs. I am truly grateful for everyone's cooperation.
When amateurs and professionals work together, we can indeed
accomplish great things. Just like small radio telescopes
connected and working as a huge telescope. IAU has recently
established a Working Group (WG) to connect amateurs and
professionals. https://www.iau.org/science/scientific_bodies/working_groups/330/. I believe that the cooperation between amateurs and
professionals will be further promoted in the future. In Japan,
there was a time when amateurs were world-class in asteroid
discovery and orbit calculation in around 1970-1980 if my memory
is correct. I hope that amateurs from Japan and the rest of the
world will play an even more active role in occultation
observation in the future. Let's develop new research fields that
cannot be done by professionals alone.
Thank you very much.
Fumi Yoshida
The David E. Laird award is given to recognize those who, more than 15 years ago, made significant contributions to occultation science and to the work of the IOTA. This year’s David E. Laird award recipient is Marek Zawilski from Poland.
Marek Zawilski is retired associate professor in Faculty of Civil Engineering, Architecture and Environmental Engineering of Lodz University of Technology, Poland. Marek Zawilski is one of the founders of the Occultation Section of the Polish Amateur Astronomers Society, which was established in 1979. He was its Chairman for almost 30 years. Since late 1960s he made a significant contribution to the field of occultation sciences as the most active promoter of those phenomena in Poland. Marek authored numerous computational programs supporting the observation of occultation events in 80's and 90's, is an active participant of ESOP conferences since the 80's, and a long-term member of the IOTA/European Section.
The main interests of Marek are historical solar
eclipses. Since 1990, he has been creating a monumental
solar eclipse cannon, which is the catalog of historical
observations of solar eclipses observed from ancient to modern
times. To create this work, Marek traveled through various Polish
and foreign archives, reads source texts mainly in Russian,
German and Latin. A movie in which Marek presents part of his
work on solar eclipses: https://www.youtube.com/watch?v=t7sYab_EKmQ
Marek sent the following message upon his notification of the award:
Dear Richard,
Wojciech phoned me one hour ago with this news. I
am really surprized! I have been active in the field of eclipses
and occultations since 1970s, so many years with such phantastic
phenomena. I am just very touched that so many people appreciated
my work, although I never cared about awards! At the moment it is
also a great consolation for me, because I look after my wife who
has had extensive cancer. Her cancer therapy is long and requires
my help throughout the day and night, so I cannot devote myself
to astronomy now as I did even a few months ago. I hope that the
therapy will bring a positive effect, but in the near future, for
example, I have to give up ESOP in Spain. I will try to be active
via e-mail and participate in on-line sessions if necessary. Let
me know if you need any information from my side -
Greetings -
Marek Zawilski
The IOTA Lifetime Achievement Award is given, as needed, to recognize outstanding contributions to the science of occultations and to the work of the IOTA over an extended period of the recipient's lifetime. The award is conferred by the IOTA Board as needed. This year's Lifetime Achievement Award 's recipient is John Broughton from Queensland, Australia. John has measured dozens of asteroids with over 100 multiple-station deployments starting in 2008, by far the most of anyone outside the USA. He has designed several special compact telescopes optimized for the work, greatly aiding multiple-station deployments, include designs that allow almost routine pre-pointing one or more nights before the event. Earlier, he pioneered the CCD drift-scan technique used by many observers, writing the Scanalyzer software to calculate times from the recorded trails. John developed the suitcase telescopes and has been an active observer for many years. Outside of his occultation work, John is most prolific amateur discoverer of asteroids in the southern hemisphere, with 1,193 asteroids discovered (including 4 near-Earth objects), 1997 - 2008 at Reedy Creek Observatory in Queensland, AU.
More activities and awards given to John:
In 2003 – started asteroid occultations using
trailed CCD images (CCD drift-scan technique)
2010 – started using
video cameras for occultations and designed the collapsible
telescopes for traveling and multi-station deployments
2002 – received the Gene
Shoemaker NEO grant by the Planetary Society to support his work
in near-Earth Asteroids
2008 – Awarded the
Berenice and Arthur Page Medal by the Astronomical Society
of Australia
2011 he formulated a method
to derive asteroid dimensions by integrating the results of
separate occultations
Asteroid 24105 Broughton named in his honor in
2005
John wrote this after receiving notification of the award:
Hi Richard,
Wow, that's awesome and something I never expected! Thanks to
whoever nominated me and all who voted.
I've just returned from a successful expedition to central
Australia where I deployed five telescopes for SwRI to record a
double occultation by the Patroclus system and will set up a
photo with the telescopes once I get organised.
Cheers,
John
For information on IOTA's awards, including previous
awardees, see the award webpage:
http://www.asteroidoccultations.com/observations/Awards/IOTAAwards.htm
Technical
sessions:
Phil Stuart presented the results of the recent occultation by Titan from July 9, 2022. Titan is the only moon in the solar system that has a significant atmosphere being 1.5bars - about 50% higher than sea-level pressure on Earths. During the occultation, Titan's atmosphere causes extinction, refraction and photometric effects. Extinction is caused by the atmosphere's haze layer, polar cap, methane clouds and banding. Phil showed a video of Titan occulting a double star taken with the 200-inch telescope on Dec 20, 2001. Here's a screen shot from that video:
The July 9, 2022 event had a low 0.66 SNR ratio, due to the small magnitude diffrerence between the target star and Titan. Thirty-six observers participated in the event in the USA and Canada including Filipp Romanov from Russia who used a remote telescope in New Mexico using itelescope.net. D and R times were poorly defined due to the gradual decline of brightness of the target star due to Titan's atmosphere. Following an analysis of the light curves, Phil deduced an approximate height of the atmosphere from Peter Ceravolo's chord. Peter's chord grazed the upper levels of the atmosphere implying its effect extends to approximately 500 km.
Vice President of Planetary Occultation Services
John Moore presented recent well observed North American
asteroid occultations during the past 12 months. John showed sky
plane profiles and in some cases 3D profiles of events from the
DAMIT shape models. Most occultation chords and the DAMIT shape
models had excellent agreement. Events shown: 957 Camelia:
2021-09-15, 780 Armenia: 2021-11-09, 535 Montague: 2021-11-10,
84522 (2002)-TC-302: 2021-11-11, 308 Polyxo: 2021-12-05, 877
Walkure: 2022-02-15, 22 Kalliope: 2022-03-02, 17 Thetis:
2022-05-04, 617 Patroclus/Menoetius a two-body binary asteroid:
2022-06-04, 90 Antiope another 2-body system: 2022-08-08.
Tony George presented the discovery of a satellite of
the Trojan asteroid 15094 Polymele. The occultation occured on
March 27, 2022 and 26 observers participated on this expedition
arranged by the SwRI. Polymele is one of 7 asteroids scheduled to
be observed by the LUCY mission - 6 Trojans and 1 mainbelt
object. LUCY was launched in October 2021 and is expected to
reach Polymele on September 15, 2027. Tony's site was near
Salina, Kansas - a 7-hour drive from his house. The predicted
time of the event at his site was predicted to +/-0.1 sec
accuracy, but his event was 6 seconds late. The occultation
results showed a normal size for the asteroid and then Tony's
event occured 6 seconds later which turns out to be the discovery
of a small moon of Polymele. The sky plane plot showed the
following profile:
The unofficial name of the moon chosen by Tony is
"Shaun". Hopefully the LUCY spacecraft will confirm
this exciting discovery when it reaches Polymele in September
2027. Congratulations Tony !!
John Moore talked about the rapid growth in the number
of asteroid observations and review of the teamwork associated
with the reductions. Worldwide events for 2021 were 1,373 and
North America events totaled 469. John showed the number of North
American observers with 20 or more observations in 2021: Bill
Hanna, Paul Maley and Roger Venable led the list. Several reasons
for the large increasing # of observations are due to the Gaia
data plus Dave Herald's and Hristo Pavlov's enhancements to
Occult and Occult-Watcher. And let's not forget the reduction
programs PyOTE, PyMovie, Tangra and AOTA. John gave special
thanks to his team of persons that help reduce the observations:
Jerry Bardecker, Norm Carlson, Bob Dunford, Ernie Iverson, Steve
Messner, Tony George (IOTA's difficult event genius) plus Johnny
Barton and Dave Eisfeldt - for Tangra support. Many comments from
the meeting attendees praised John for the outstanding work he
and the group has done.
Ted Blank presented a talk about controlling the heat
buildup and associated thermal noise in the RunCam Night Eagle
astro cameras. A 2-inch PVC part can be used to provide
insulation and insert the camera into a 2-inch eyepiece holder to
achieve the needed focus. Nowadays a 3D printer can make the same
adapter. Ted showed a video clip of the noise buildup after 30
minutes of operation. The increased background noise makes
extracting the occultation events more difficult. He suggested
using just 5V to run the camera vs. the usual 12V power. Also one
can use a passive heat sink to reduce the heat and noise buildup.
Another idea Ted uses is a small fan to cool the camera. Ted then
showed a comparison video of the heat buildup on the bare camera
vs. adding the heat sink, fan and using just 5V to operate the
camera. Here's a screenshot showing the noise reduction:
Dr. Richard Nolthenius presented ideas
to help identify and time the occultations of faint stars in
bright backgrounds using PyMovie and PyOTE. The core idea is to
make use of PyMovie’s ability to create “finders”.
The original intent of finders was to better position the
apertures before analysis. However, finders have an advantage vs.
simply increasing the integration setting. If the sky is bright
(twilight, nearby bright moon, light pollution), it may be
impossible to increase the integration setting w/o saturating the
pixels. In this case, what is needed is not to sum the
brightness, but instead average it over a longer time interval.
For longer events, this could still capture the actuality of an
occultation but which might fail the usual tests with the
standard PyMovie/PyOTE procedures. By averaging frames, the
random bright sky pixels include the darkness which is not the
case with the star’s pixels. Further, PyMovie already has
coding to construct finders and then adjust the
brightness/contrast to better show the star against the sky. If
PyMovie can be induced to create a new video from an automated
assembly of “finders”, or even perhaps
“finders” which overlap in time, this would be useful.
If the finder is optimally significantly longer than the
integration exposure setting, then the time resolution can be
improved closer to the original setting vs. the longer
“finder” setting. PyOTE and PyMovie would require new
coding to accommodate this.
He illustrated this technique with a 1 minute series of
“finders” for the Aug 8, 2022 occultation by Quaoar, a
high rank event with high probability the occultation seen is
real. This is a 15.3 magnitude target only 12 degrees from a 90%
moon, seen in an 8” telescope at 16x Watec integration. He
also showed the PyOTE reductions by standard means, for both Kirk
Bender and his data.
Rick's power point talk is located here: https://www.dr-ricknolthenius.com/Apowers/IOTA-NewTechniqueFaint.pdf
Tony George presented two new functions of Pyote: 1) Evaluation of detectability and 2) Analysis of a single point event. The Single-point Event Tool can analyze a single-point event to determine if it is statistically distinct from baseline noise in the light curve. A Monte Carlo simulation of correlated noise equivalent to the light curve noise added to a straight line 50,000 times is used to determine if any noise spikes are representative of the single-point event. If the single point passes the test, it is statistically significant at the equivalent 4-sigma level and can be further investigated as a potential event. If it does not pass the test, the event should be considered to be due to noise, except if there are corroborating chords nearby to evaluate the validity of the single-point event.
Next was the Event Detectability tool. This tool can be used to determine if an event was detectable, in the event an observer believes there was a miss. If the test indicates that an event of a certain magDrop and duration was detectable, and not such event was observed, then the observer can reliably claim there was a qualified miss for any event longer than the detectability limit. Also, it was demonstrated how the tool could be used to process any light curve, with or without an embedded event, to use for future planning of observation sessions. Users were encouraged to record a variety of light curves for different cameras and integration settings, as well as at different altitudes and observing seasons to use for planning for future events. Then when a future event presents itself, the recorded light curve that would approximate the equivalent camera/settings/altitude/seasonal noise could be used to see if the upcoming event would be detectable given the upcoming magDrop and duration. Roger Venable suggested that open galactic clusters could be used to record a variety of star magnitudes at the same time.
Dave Herald talked about the use of the
double star function in Occult. An important point is the treat
the observer's identification of the brighter/fainter star with
skepticism if the magnitude differences aren't great. This is a
major issue in matching events to components. He described the
basic process of fitting the observations using least squares to
generate a position angle and separation. Light curves are also
encouraged to be submitted to determine the magnitude drop for
step events on the D and R sides of the occultation. Smaller step
events are sometimes difficult to verify compared to the noise in
the data.
Double star events can result in more than one solution for the
position angle and separation. With a unique solution - you know
where the asteroid is relative to both stars. Double solution -
you know where the asteroid is relative to one star, but the fit
is ambiguous for the other star. In this case, one observer might
record both step events and a 2nd observer might only record one
step event. A four solution case - the asteroid location is
ambiguous for both stars.
An astrometry issue: occultation discoverd double stars are not
usually resolved in the Gaia data. The issue here is to match the
photo-center of the event to the Gaia position. Dave showed how
Occult does this with the double and 4 solution cases.
Occult has a database of double star discoveries by asteroid
occultations - as of today's date there are 199 discoveries. To
get a discovery of a new double star into the Washington
Double Star Catalog (WDS), the USNO
requests that the discovery must be published - they will not
accept a direct notification. The Journal of Double Star
Observations (JDSO.org) is the preferred journal for announcing the discovery.
The Meeting formerly ended at 0:50 UT August 14th. Discussions continued among the attendees.
-----------August 14 - 20:00 UT - Meeting begins. Online attendees reached 72 persons and this number fluctuated throughout the meeting---------------------
Vice President Dr. Roger Venable talked about making unattended remote observations. He showed example locations for good sites using Google Earth and how he sets up just off highways. He recommended painting your equipment black so as not to be visible from passing cars. In setting up a pre-point station, he uses a small piece of wood for the tripod legs to rest on so they don't sink into the ground. Dew shields are also advised especially in humid climates. He also leaves a note on the equipment for onlookers requesting that they "DO NOT TOUCH" with an explanation of what the equipment is for. Care must be taken when settng up telecopes so as not to break any laws such as trepassing, going past or opening gates to a fence, setting upon private lands without permission, etc. A group discussion followed with experiences of observers dealing with Police, landowners and identifying equipment parts in the dark such as battery terminals.
Roger next talked about the appearance of light curves of near-Earth asteroid events. For faint main-belt objects at occultation time the brightness usually drops to zero (as the asteroid is usually not visible with our equipment) and the D and R are usually instantaneous. He showed a few light curves of near Earth objects and some common features of the light curves. Spikes in the light curves can be caused by fresnel and diffraction effects and by the star's diameter. Sometimes a central spike appears on a light curve of an asteroid - this is a diffraction effect (wavelength dependent) due to the size of the asteroid and not due to an non-existent atmosphere. Diffaction spikes can occur depending on what part of the asteroid is occulted (center or edge) from the ground position of the observer. A high recording frame rate can help identify diffraction spikes. Diffraction, frame duration and star diameter can affect the occultation timings of small objects such as Apophis (~500 ft size) compared to larger main belt objects of 20km and larger.
President Steve Preston next presented the best asteroid occultations opportunities in North America for 2023. The events were of stars down to magnitude m = +10 and he showed the Occult path maps for each one. The best one is when 319 Leona occults Betelguese on December 12, 2023 over south Florida, Mexico plus Europe. If visible, this should be a spectacular naked eye event with the maximum duration of up to 11 seconds.
Dr. David Dunham talked about
near-Earth asteroid events in the coming year. These include:
433 Eros
1620 Geographos
1866 Sisyphus
2102 Tantalus
3122 Florence
3200 Phaethon
4179 Toutatis
29886 Randytung
65803 Didymos has 160m moon 1.2 km away
95802 Francismuir
99942 Apophis
10995 Bennu
163693 Atira - has an approx 1km size moon 6km away
Trojans occultations for 2023:
617 Patroclus - has the moon Menoetius
624 Hektor
911 Agamemnon
1143 Odysseus
1173 Anchises
2241 Alcathous
3548 Eurybates - has a small 1km moon Queta discoverd by HST.
11351 Leucus - LUCY mission target
15094 Polymele - has a 5km moon 200 km away
21900 Orus
58931 Palmys
Special Main-belt asteroids in 2023:
16 Psyche
90 Antiope
26 Kleopatra - has 2 small moons
234 Barbara - possible contact binary asteroid
253 Mathilde
319 Leona
513 Centesima
762 Pulcova- has a 15km Moon
957 Camelia
2258 Viipuri - may have a 5km moon
4337 Arecibo - Binary discovered in 2021 confirmed by Gaia
4552 Nabelek
33074 1997 WP21 - might have a 9km moon
52246 Donaldjohanson - LUCY
172376 2002 YE25 - possible binary asteroid
David then showed a list of Quaoar (size ~ 550 km) and Weywot
(moon of Quaoar, size ~ 170km) occultations for the remainder of
2022 and 2023. He then showed a map of occultation stars brighter
than m = +9.0 for North America he is working on for the RASC
Handbook.
David next talked about the 65803 Didymos events for the rest of
2022 and 2023. Didymos is the target of the DART mission to
impact it and test the planetary deflection technique of a
non-hazardous asteroid. Following the impact, the orbit will
change slightly. Events in 2022 with stars down to m = +12.0 are
numerous - major ones are: Aug 17, Aug 23, Aug 24 and Aug 25, Sep
3, Oct 2, Oct 8, Oct 10, Oct 12, Oct 15, Oct 17.
Didymos opportunities for 2023: Jan 1, Jan 3, Jan 5, Jan 5, Jan
6, Jan 9, Jan 10, Jan 12, Jan 16, Jan 18, Jan 21, Jan 23, Jan
28,Mar 2, Mar 20, Apr 9, Apr 25, May 4.
Dave Herald talked about issues to think about regarding light curve analysis. Event time accuracy - should we aim for highest time precision? When is sub-frame timing desireable? Fact is 95% of occultation astrometry has an uncertainty of >1.0 mas. Shape resolution depends on the number of chords. Single chord events have no shape info, the more chords (with good spacing) the better in determining the shape. With a better shape the "center of figure" can be determined resulting in a more accurate astrometric position for orbit updating. Then he discussed dealing with background subtraction. The purpose of background subtraction is to set the zero level of the light curve to zero light. He showed 3 light curves of the Erida event 2022 Jun 24 recorded by Dr. Richard Nolthenius. The light curves were made by PyMovie and Tangra with usual and average background subtraction in AOTA. Background subtraction results is a more distinguishable event from the data points compared to not using it.
Magnitude drops - realistically with our video equipment
mag drops can be measured down to 0.1 mag precision. Noise in the
event can influence this. Some observers have reported mag drops
to 0.001 mag! This is not credible or sensible - Dave suggested
we report mag drops as a percentage of full light.
Gamma function - On our video cameras the gamma function changes
the vertical response in a non-linear manner. It should always be
set to 1. With instantaneous events the non-linear vertical
response has a minimal effect to event time. Gamma set to less
than 1 affects magnitude changes. Magnitude changes are generally
poorly determined from our 8-bit light curves. However if
adjusting Gamma enables one to make an observation, by all means
do it.
Dave Gault talked about time stamping delays associated with the computer. There are acquisition delays, delays from VTI to camera and internal camera processing delays to the computer. More delays are within the PC's used for timing. Questions are: does anyone test their system for these delays? And correct their times for this delay? Delays can be 53 - 68 millisec. Hristo Pavlov and Dave Gault wrote an article on this problem in the Journal of Occultation Astronomy (JOA) issue 2020-3.
Dave Herald next talked about shape model analysis with Occult. Shape models provide the shape, not size of the asteroid. The shape provides a volume-equivalent diameter to be measured. Well observed events can help locate the center of mass and not the center of figure. Dave showed sample Occult plots overlaid with DAMIT shape models and location for the center of figure. The center of figure point is used to determine the astrometric position for MPC reporting. Multiple occultations by the same asteroid can also be used to get the axis of rotation. With the axis of rotation known, the asteroid can be rotated to show different orientations. He then showed an Occult demo of Eros rotating based on shape and axis models.
The meeting ended at 00:10 UT August 15th.
Joan Dunham will conduct a zoom session at 10PM EDT time in preparation for the small 4.5km asteroid 3122 Florence event Aug 16, 2022 however cloud problems could foil the observation.
The minutes of all IOTA's annual meetings are at: http://www.poyntsource.com/Richard/IOTA_Annual_Meetings.htm
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.