Transcript IAU 29th General Assembly

Report on the 29th General Assembly
of the International Astronomical Union
2015 Oct. 17, Las Vegas, Nevada
International Occultation Timing
Association - Annual Meeting
David & Joan Dunham
August 2 – 14, we returned to the USA, but only to Honolulu, Hawaii,
to attend the 29th General Assembly (GA) of the International
Astronomical Union (IAU). IAU GA’s take place every three years and
last for two five-day sessions spread over two weeks. Previously, I
attended IAU GA’s in 1967 (Prague, Czechoslovakia), 1970 (Brighton,
UK), 1976 (Grenoble, France), 1979 (Montreal, Quebec), 1982 (Patras,
Greece), and 1988 (Baltimore, Maryland).
They provide a unique opportunity for astronomers worldwide working
in all fields of astronomy to come together. In addition to the core
administrative meetings, the General Assembly also includes a
substantial and attractive scientific program. This usually comprises
two series of three Symposia each lasting for three days, and scheduled
during the first and second weeks, respectively. Fifteen to twenty more
specialized "Focus Meetings" are also held, with up to five topics
running in parallel. In addition, two full days are reserved for Division
Meetings, with no overlap with the general program.
Symposia of the 29th IAU GA included:
•IAUS 315 – From Interstellar Clouds to Star-forming Galaxies: Universal
Processes?
•IAUS 316 – Formation, Evolution, and Survival of Massive Star Clusters
•IAUS 317 – The General Assembly of Galaxy Halos: Structure, Origin and
Evolution
•IAUS 318 – Asteroids: New Observations, New Models
•IAUS 319 – Galaxies at High Redshift and Their Evolution Over Cosmic
Time
•IAUS 320 – Solar and Stellar Flares and Their Effects on Planets
A special session described first results from Gaia (first year obs.)
Symposia programs & other IAU details are at
http://astronomy2015.org/science_program
Focus Meetings of the 29th IAU GA included:
•FM 1 – Dynamical Problems in Extrasolar Planets Science
•FM 2 – Astronomical Heritage: Progressing the UNESCO–IAU Initiative
•FM 3 – Scholarly Publication in Astronomy: Evolution or Revolution?
•FM 4 – Planetary Nebulae as Probes of Galactic Structure and Evolution
•FM 5 – The Legacy of Planck
•FM 6 – X-ray Surveys of the Hot and Energetic Cosmos
•FM 7 – Stellar Physics in Galaxies Throughout the Universe
•FM 8 – Statistics and Exoplanets
•FM 9 – Highlights in the Exploration of Small Worlds (results from Rosetta, Dawn, New Horizons)
•FM 10 – Stellar Explosions in an Ever-Changing Environment
•FM 11 – Global Coordination of Ground and Space Astrophysics and Heliophysics
•FM 12 – Bridging Laboratory Astrophysics and Astronomy
•FM 13 – Brightness Variations of the Sun and Sun-like Stars
•FM 14 – The Gravitational Wave Symphony of Structure Formation
•FM 15 – Search for Water and Life's Building Blocks in the Universe
•FM 16 – Stellar Behemoths - Red Supergiants Across the Local Universe
•FM 17 – Advances in Stellar Physics from Asteroseismology
•FM 18 – Scale-free Processes in the Universe
•FM 19 – Communicating Astronomy with the Public in the Big Data Era
•FM 20 – Astronomy for Development
•FM 21 – Mitigating Threats of Light Pollution & Radio Frequency Interference
•FM 22 – The Frontier Fields: Transforming our Understanding of Cluster and Galaxy Evolution
On behalf of IOTA, I gave four poster presentations, all
during the first week:
1. Results from Asteroidal Occultations (Josef Durech was
there)
2. Double star results from occultations
3. Solar diameter results from total and annular solar
eclipses
4. Plans for the 2017 August 21st total solar eclipse
In the following, I give at least the title slide of each; the full
posters (Power Point files) will be given in a subfolder in the
IOTA meeting presentations section
S318p.15 – Sizes, Shapes, and Satellites of
Asteroids from Occultations
David W. Dunham*, David Herald, Steve Preston,
Bradley Timerson, & Paul Maley, International Occultation
Timing Association (IOTA); Eric Frappa, IMCCE, Paris; Tsutomu
Hayamizu, Japanese Occultation Information Network; John Talbot,
RASNZ Occ’n Section; and Atila Poro, IOTA/Middle East Section, Iran
* Email [email protected] Cell phone 301-526-5590
International Astronomical Union - General Assembly Honolulu,
Hawaii, 2015 August 3 – 7 - Control ID 2258262
For 40 years, the sizes and shapes of dozens of asteroids have been determined from observations of
asteroidal occultations. Some of the first evidence for satellites of asteroids was obtained from the early
efforts; now, the orbits and sizes of some satellites discovered by other means have been refined from
occultation observations. Also, several close binary stars have been discovered, and the angular diameters
of some stars have been measured from analysis of these observations. The International Occultation
Timing Association (IOTA) coordinates this activity worldwide, from predicting and publicizing the
events, to accurately timing the occultations from as many stations as possible, and publishing and
archiving the observations.
Occult Watcher Planning Tool
Used by observers to find potential occultations that they can observe, filtered by
distance (larger distances for mobile observers), star mag., etc., and give event details,
including links to star charts, etc. Through a Web interface, mobile observers can then
set up to fill gaps in coverage by those at fixed observatories.
Lightcurve from Dunham Station #3 for 2011 Dec. 28th occ’n of
SAO 138052 = HIP 54719 by (407) Arachne e. of Huntsville, TX
Video analyzed by Scotty Degenhardt. The site was a graze near the n. limit; the star
disappeared completely behind 3 features on the edge of the asteroid.
Still the record, Scotty observed from 14 stations in Oklahoma !
Scotty & I agreed
before that I would
cover the n. side & he the
s. side, so each of us could deploy more stations
across a shorter distance. This time, the path shifted
s. so he hit the jackpot. 3 LA region fixed observers expected no event,
but ended up defining the southern part of Hertha.
2011 July 19 occultation of LQ Aquarii by the binary
asteroid (90) Antiope observed in western USA
Above is the
best direct
image of
Antiope, by
Bill Merline
using AO
with Keck
3d before the
occultation;
it allowed a
good prediction of the
objects’
orientation.
Sky-plane plot, 2012 Jan. 19th
(911) Agamemnon occultation
Below:
Above:
Agamemnon: Axes 190.6 0.9 by
143.8 1.5 km, PA minor axis -69.3
1.3, center X 4661.6 0.4 km, Y
3113.7 0.6 km; Disappearances are
on the right side. The probable
satellite is plotted as 9-km circle (but
it’s more likely about 4 km across)
0.0931 (278 km in the plane) from
Agamemnon’s center in PA 93.8
Light curve by Steve Conard (sta. 6)
using a 14-in. SCT at his observatory
at Gamber, Maryland
RASC Observer’s Handbook and
http://www.occultations.org
The RASC Observer’s Handbook contains predictions of the 70 best asteroidal
occultations visible from North America and Hawaii during the year.
Many occultation YouTube videos are linked to from:
http://www.asteroidoccultation.com/observations/YouTubeVideos.htm
Listed on this web page are, in groups from top to bottom,
Lunar Occultation Videos; Asteroidal Occultation Videos; Jupiter/Saturn Satellite Events
Miscellaneous Events (most of them are solar eclipse videos made near the edges of total
and annular solar eclipse paths)
DGp.1.11 - Close Double Stars from
Occultation Video Recordings
David W. Dunham, Anthony George,
Brian Loader, and David Herald,
International Occultation Timing Association (IOTA)
and high-speed CCD observations
by Andrea Richichi, National Astronomical
Research Institute of Thailand
International Astronomical Union - General Assembly
Honolulu, Hawaii, 2015 August 3 – 7
Control ID 2256339
Long History of Double Star Discoveries
from Lunar Occultations; Antares was 1st
• Duplicity of Antares discovered during a lunar occultation
observed at Vienna by Johann Tobias Bürg on 1819 April 13. I
observed a graze of Antares by the thin crescent Moon on 1969
January 25
• Contrast of the red giant star and its 5th-mag. blue companion
was striking
• I recorded an Antares graze with a color video camera and 12cm
SCT from Western Australia on 2009 Feb. 17
• Show events of both components, 19:44:10 to 19:44:25 and
• 19:47:00 to 19:47:30
Reduction profile by Dr. Mitsuru Sôma at the National
Observatory, Japan. The lunar mean limb is the horizontal line
at 0 and heights are in units of  at the Moon’s mean distance
(1 then is 1.86 km). “Axis Angle” is position angle measured
relative to the Moon’s axis of rotation. For each observer (and
each stellar component), the star follows a parabolic arc.
Cloud interference, esp. near the end, resulted in some spurious
events. Kaguya & LRO laser altimeter profiles are very accurate.
IOTA’s Efforts to Catalog Possible Double
Star Discoveries from Lunar Occultations
• In the early 1970’s, I worked with David Evans’ group at the Univ. of Texas
to analyze hundreds of photoelectric lunar occultation observations
• I worked with a student, Don Stockbauer, to create a list of possible doubles
from lunar occultations using:
- Photoelectric occultations, Univ. of Texas and other published obs.
- Grazing occultations observed since 1962
- Total occultations, both current and from published obs.
- Spectroscopic binaries (including 1-line) were included to
encourage observation of their occultations.
• Too many dubious events were included; especially visual observers often
reported “gradual” events more likely due to Fresnel diffraction, and
sometimes stellar angular diameter
• Codes that indicated “certain, events in clear steps”, “probable”, and
“possible” were lost when transferred to currently-used lists, for occultation
predictions but also even the Washington interferometric catalog
IOTA’s Recent Double Star Efforts
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We now strongly encourage observation with relatively inexpensive video equipment
to better quantify the observations, and obtain at least approximate photometric
information using specially-developed software for analyzing video records, esp.
Limovie from Japan and Tangra from Australia
We encourage observation of stars with a past claim of duplicity;
Over 90% of those show no evidence of duplicity with the new video obs.
We encourage observations of the same occultation of a suspected double from widelyseparated locations with real-time coordination using “Occult Watcher” Web software.
If the same lunar occultation is observed from widely-separated locations (with the
contacts at different position angles), the separation and position angle (P.A.) can be
uniquely determined; otherwise,
Only a “vector separation” in the P.A. of the occultation is found
If orbital motion slow, “vector separations” from events a few months apart can give
approximate double star separation and P.A.
Results are published in JDSO periodically, including lists where the new observations
indicate “probably single” for previous occ’n duplicity claims
We have begun a collaboration with the current Kepler2 ecliptic program, to obtain (or
find past) occultation lightcurves of their program stars, to help assess close stellar
duplicity that might affect Kepler’s analysis for exoplanet transits. We are starting to
collect and archive new and past occultation lightcurves.
Multiple events of 2 close components from a video recording of
a lunar grazing occultation observed in Australia
X63280,
2014 Dec 31
23
Professional Work
• Is mainly coordinated now by Andrea Richichi at the National
Astronomical Research Institute of Thailand, [email protected]
• He worked before for a long time at the European Southern
Observatory, where he still makes most of his observations
• Most observations are recorded in the infrared, allowing higher
S/N and even some daytime observations
• Observations are concentrated on times when the Moon
traverses the Galactic center region, an area of obvious high
interest; a hundred occultations might be recorded in a single
night
• Passages over the Pleiades and other interesting clusters are
also observed
• The equipment is set up so that it can be used during “dead
times” between other astronomical observations
Instruments & Detectors
 Photometers,
photomultipliers, InSb diodes
 APD, SPAD
 CCD (drift scanning)
 NIR Arrays (subwindow)
 Specialized small format arrays (AO)
2.4m f/10 TNT, alt. 2400m since Mar. 2012
Lightcurve of occultation of SAO 80827 by (160) Una
recorded by Dennis DiCicco at his observatory in
Sudbury, Mass., 2011 January 24
Video at
http://www.asteroidoccultation.com/observations/YouTubeVideos.htm
FM13p.21 – Solar Diameter Measurements
from Eclipses as a Solar Variability Proxy
David W. Dunham*, Internat’l Occultation Timing
Assoc. (IOTA); Sabatino Sofia, Yale Univ. – retired;
Konrad Guhl, IOTA/European Section; and David Herald, IOTA
* Email [email protected] Cell phone 301-526-5590
International Astronomical Union - General Assembly Honolulu,
Hawaii, 2015 August 3 – 7 - Control ID 2257941
Since thermal relaxation times for the Sun are thousands of years, small variations of
the Solar intensity are proportional to small variations of the Solar diameter on
decadal time scales. In a combination between observations and theory, reliable
values of the relation constant W are known, that allow transformation of historical
variations of radius into variations of the solar luminosity. During the past 45 years,
members of the International Occultation Timing Association (IOTA) have observed
20 annular and total solar eclipses from locations near the path edges. Baily’s beads,
whose occurrence and duration are considerably prolonged as seen from path edge
locations, were first timed visually, mostly using projection techniques.
Overview
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IOTA’s long term solar radius measurement research
Observations near central eclipse path edges since 1970
Analysis of historical obs. back to 1715; look for more
Re-analyze all obs. with accurate profile data- eg, LRO
These large tasks manageable with some help from
others in and outside of IOTA
Solar Radius Determinations from Solar Eclipses
The radius correction, delta-R, is relative to the standard value at 1 A.U., 959.63 arc seconds.
All have been reduced using David Herald’s WinOccult program and analyzed with the Solrad
programs. The Delta-R values are from 2-parameter solutions using bead events within 30° of the
30
poles to use the better accuracy of the lunar polar profile as explained in a previous slide.
Summary of Remaining Work
• Search publications and local university archives for past
observations to analyze
• Work remains to be done, for example, on the rather wellobserved US eclipses of 1806 and 1869
• The Internet facilitates connection with local historians who can
often find information about past observations.
• Google Earth and other GIS tools make position determination
much easier than using topo maps
• Re-analyze all obs. with accurate profile data- eg, LRO
• New observations with previous and modern techniques,
especially at the 2017 eclipse, are needed to calibrate the earlier
observations
• Anyone near a university or a central eclipse path, or even with
just internet access, can help
DEp.1.08 – Plans to Observe the 2017 Total
Solar Eclipse from near the Path Edges
David W. Dunham* and Richard Nugent, International Occultation
Timing Association (IOTA); Konrad Guhl and Hans-Joachim
Bode, IOTA/European Section
* Email [email protected] Cell phone 301-526-5590
International Astronomical Union - General Assembly Honolulu,
Hawaii, 2015 August 3 – 7 - Control ID 2258483
The August 21st, 2017 solar eclipse provides a good opportunity, to time the totality
contacts, other Baily’s bead phenomena, and observe other dynamic edge
phenomena, from locations near the edges of the path of totality. A good network of
roads and generally favorable weather prospects means that more observers will
likely be able to deploy more equipment than during most previous eclipses. The
value of contact and Baily’s bead timings of total solar eclipses, for determining
solar diameter and intensity variations, was described in an earlier presentation in
Focus Meeting 13. This poster will concentrate on how observations of different
types that have been used during past eclipses can be made by different observers,
Unique opportunity to deploy greater resources than usual
Primary goals for this eclipse
• Continuation for IOTA’s long term solar radius
measurement research
• Standardization of video equipment
• Standardization of solar filters
• Co-located use of previous techniques (visual,
telescopic projected image, filtered telescopic video)
• 2nd use of narrow band filters (1st was for the May 20,
2012 annular eclipse)
• Desired Results: calibrate with Picard satellite data and
with methods used at previous central eclipses
IOTA Standardization Attempted for
the May 2012 Annular Eclipse
Equipment Specifications
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Telescope aperture: 75mm – 100mm
Field of View – 15' - 20'
Solar filter – Baader brand – in sheets
Narrow band filters – Wratten #23, #56
Attempt to observe in Picard wavelengths
Video camera: PC164C(EX-2), Watec
902H
Ted Swift, S. Limit of May 2012
15 sec interval
Annular Eclipse
Unfortunately, clouds prevented observation
near the northern limit.
January 24, 1925 Total Solar Eclipse – Boy Scouts and Con Ed
workers found the southern limit by observing at one-block intervals
across Manhattan. Similar efforts might be made at towns straddling
the limits of the August 2017 TSE, a public outreach opportunity
Two occultations during the GA
• Aug. 5, grazing occultation of 6.5-mag. 96
Piscium across southern Honolulu with path
only a mile south of our hotel (first graze where
we walked to the graze zone). We brought a
120mm maxi and due to the 73 altitude, we
brought & used a paver mount. John Broughton
plans to make lighter versions of those for better
air transport.
• Aug. 13, possible occultation of 9.6-mag. star by
(1197) Rhodesia – I thank Ernie Iverson for the
pre-point charts for this & all AU events
August 5, 4:25am HST, graze of 6.5-mag. 96 Piscium 7 from
northern cusp of 67% sunlit Moon, altitude 73
Possible Oahu occultation of 9.6-mag. PPM 171360 by (1197)
Rhodesia predicted on 2015 August 13 at 7:53 pm HST
= =PPM
PPM171360
171360
The target star is in
northern Aquarius
at J2000
RA 21h 09m 46.2s
Dec +01 07’ 18”
Predicted size of (1197) is 49 km. The expected
central Duration is 3.3s with a 5-mag. drop. The
Predicted altitude is 24 in the east.
More about this event will be posted
here on Thurs. & Friday. Contact
David Dunham if you might try to
observe this. [email protected]
Cell 301-526-5590
Note published in IAU GA Newspaper
Rhodesia Occultation Results
On target, cloud moved over
FOV few seconds after the
predicted time, a miss, but
Sherrod’s AR miss (purple)
was closer. Bart Billard
recorded his first positive at
Fredericksburg, VA with a
CCD drift scan.