The
International Occultation Timing Association 23rd Annual
Meeting at
October
29-30, 2005
|
IOTA's parking attendants at the |
IOTA Vice President Paul Maley with
his portable telescope system |
IOTA President Dr. David Dunham
showing the Lunar graze profile obtained from the July 18, 2005 Antares
graze over |
|
David Dunham and Danny Falla |
Secretary/Treasurer Dr. Art Lucas,
who arranged this years meeting |
Sandy Bumgarner and Dr. Roger Venable discussing video techniques |
This year marked the first meeting broadcast
over the web. Thirty-two members and attendees were present. This
included fifteen persons present at the Oklahoma State University Physics
building and up to seventeen persons watching via a Webcast. The minutes of the
meeting are below:
Art Lucas Receives Honorary Doctorate
New Google Earth Maps for Occultations
GPS and WWV Video Time Insertion
Pre-Pointing Method for Telescope systems
Solar Radius Research from Solar Eclipses
87 Sylvia has two confirmed asteroidal moons
71 Noibe's possible large Satellite
Highlights of the 23rd
IOTA Annual Meeting, 2005
by Richard Nugent, Executive
Secretary
The 23rd annual meeting of the International Occultation Timing
Association was held Saturday and Sunday October 29-30, 2005 at Room 110 of the
Physics building at the Oklahoma State University (OSU) in
Thirty-two members and attendees were present. This
included fifteen persons actually at the Physics building and up to seventeen
persons watching via a webcast:
President David Dunham from
Vice President Paul Maley from
Executive Secretary Richard Nugent from
Secretary Treasurer Art Lucas from
Barb Lucas from
Roger Venable from
Rick Frankenberger from
Derald Nye from
Bob Sandy from
Derek C. Breit, Daniel Falla, Sandy Bumgarner from
Webcast members present:
Dave Gault, Australia; Ed Morana and Charles Poplinger, California; Pedro
Valdez Sada, Mexico; John Graves (editor Occultation Newsletter, ON),
Tennessee; Willem Van Leewen, Netherlands; Walt Robinson (IOTA’s Webmaster),
Kansas; Jim Stamm (Vice President Planetary Occultations), Arizona; Rocky
Harper and Dave Clark, Texas; Tony George, Oregon; Suresh Singh, India;
Vincenzo Flourincio, Italy; and Warren Grider, Oklahoma.
Art Lucas opened by introducing
Dr. McKeever, Vice President of Research at OSU. Dr. McKeever immediately
mentioned the long history of contributions to the University by Art and
Barbara Lucas, including the starting of the first observatory at OSU. For this
and his many other contributions to OSU’s Physics Department over the years,
Art received the highest honor an individual can receive: an honorary Doctorate
in May 2004. A round of applause followed this announcement. Congratulations to
Art Lucas for this outstanding achievement!
President David Dunham opened the meeting and asked the attendees to
introduce themselves. Following the introductions of the local attendees, the
webcast meeting began with an inappropriately timed (for us) maintenance power
outage at the host location at the California Institute of Technology. The
webcast was delayed by approximately 2 hours, including all of the business
session.
Business Meeting, Saturday, October 29
President David Dunham motioned the floor to open the business meeting and
was seconded by Roger Venable. Secretary/Treasurer Art Lucas gave a
report of IOTA’s financial status. IOTA is in good financial shape and has
shown a positive cash flow from 2004 to 2005.
Lucas reminded everyone to check their mailing labels for their own dues
expiration date. Lucas explains this in the page that he encloses with each ON,
but many don’t read it far enough and just assume that they need to renew when
they see the "renewal" page. Some members are way ahead on their
dues, and the credits will not be refunded. Lucas remarked that every mailing
of ON results in a flurry of membership dues payments.
Lucas also mentioned that Occultation Newsletter (ON)
editor John Graves has a lack of material for publishing and
encouraged IOTA members to submit their articles and observations, since this
is the medium where IOTA maintains a permanent record of its continuing
activities. Overall, IOTA seems to be in good financial shape. And since the
bulk of IOTA’s expenses is the ON, the membership should take
advantage of it and submit material to John Graves, whether it be observations,
techniques, etc.
There was no opposition to the financial report, and it was accepted by the
members. An original copy of the Annual Financial Statement is on file with the
Executive Secretary.
Executive Secretary Richard Nugent noted that the 2004 meeting
minutes were published in ON. In 2004, it was considered that
IOTA seek publication of a "Proceedings" similar to other specialized
astronomical groups, and Nugent had received some quotes from the Astronomical
Society of the Pacific. They were interested in publishing such a volume and
were also seeking a minimum of approximately $4,000 in sales. This would have
come to about $55/volume. At that time ON was very short on
submission so it was decided to drop the idea of an outside source for a
Proceedings publication.
Art Lucas has asked the members to seriously consider taking over his job as
Secretary/Treasurer due to his age/health reasons. The main duties of the
Treasurer are:
1. Mail the ON from the printer,
2. Deposit member dues checks into the bank,
3. Make a year end financial statement (2 pages),
4. Make a membership list,
5. Prepare lists for
distribution, mainly, annual predictions.
Chad Ellington volunteered to do the secretarial work, but not
the treasurer’s work. Art said this would be very helpful, and
Dunham told the group that the yearly Sky and Telescope (S & T) asteroid
occultation articles would probably be much shorter and published several times
per year. This being due to the initial large uncertainties in the paths of
these events. A world map of the better 2005 events is now on the S & T
website.
Richard Nugent presented the status of the IOTA Observer’s Manual. He
brought a paper copy (256 pages) of the completed chapters and appendices to
pass around. Remaining chapters needed to complete the manual are solar
eclipses (limited to IOTA solar radius research and lunar polar diameter
measurements), grazes and IOTA history. The results of IOTA’s long term solar
radius experiment just recently became available in September 2005 so Nugent
now has the needed results to proceed with the eclipse chapter. Nugent gave a current
copy of the manual (electronic form) to Sandy Bumgarner and David Dunham. Due
to the large size of the manual, a new website will be used to show the
chapters. It is located at http://iota.jhuapl.edu/iotaman.htm
With no further business, at 10:55 it was motioned to close the business
portion of the meeting, Bob Sandy seconded the motion and the business meeting
was closed.
President David Dunham began the technical sessions asking for
preliminary results of the asteroid event by 790
Bob Sandy: 45 km north of predicted center, 6.6 second occultation,
Derald Nye: Dew and clouds, 30 km north,
Paul Maley, 8 second occultation 11 km north,
Richard Nugent: 7 second occultation, 40 km south of predicted center,
Rick Frankenberger: Clouds,
Roger Venable/Derek Breit: Clouds/dew.
11:20 AM 12:00 Noon --- Break
David Dunham mentioned that Steve Preston now has predictions for all
asteroid occultations for 2005 and 2006 on his website. Full updates are given
for events about a month in advance, with preliminary updates for the rest. He
also mentioned that valuable accurate asteroid astrometric observations comes
from the Jet Propulsion Laboratory’s Table Mountain Observatory since they have
a telescope that is not restricted to meridian observations, but the bulk of
the observations are still provided by the FASTT Meridian Transit telescope of
the U. S. Naval Observatory in Flagstaff, Arizona. Hugh Harris is now providing
most of those observations after the unfortunate recent death of Ron Stone, who
established the FASTT program with the important linkage to the accurate
Hipparcos/Tycho catalogs that became available from ESA in 1997.
A brief discussion began about the possible use of automated telescopes to
capture asteroid occultations (and occultations by asteroidal satellites). IOTA
Vice President Paul Maley and others agreed that it is very difficult to
recruit general observers for asteroid events unless the observation is very
convenient (i.e., done from their backyard, a bright target star, Saturday
night, before 12 midnight, etc.). Such occultation telescopes might be
controlled from the internet. Internet telescopes exist to do this, however
few, if any, are portable; they must be reserved long in advance; and many have
fees associated with their use. More discussions on this continued during the
breaks.
Chad Ellington showed the use of Google
Maps for plotting and viewing asteroid event paths. The program Google Earth
can take Steve Preston’s detailed Info files to overlay the asteroid ground
track on a map with just a few mouse clicks. "Kiwi" Geoff Hitchcox
wrote the software to accomplish this. These maps are clickable to show terrain
to extraordinary detail, and can calculate the distance of a line (using mouse
dragging) from the center of limit of the path. Charlie Ridgway in
http://digitalmagic.i8.com/Astronomy/Occultations/
12:30 – 1 PM- Lunch down the hall hosted by Art and Barbara Lucas.
Dr. Peter Shull showed slides of the OSU’s HS Mendenhall Observatory
located 6 miles southwest of
Several GPS time/WWV video time inserters are in use for occultation work.
The current status of some of the available units was discussed by the
attendees:
Manly WWV Time inserter: This is the oldest time inserter, developed
by Peter Manly in
KIWI OSD: "Kiwi" Geoff Hitchcox designed a GPS time
inserter that displays LAT/LONG, Altitude and GPS time. It has a backup time to
keep the time display going in case the GPS signal is lost (built in quartz
clock), allows NTSC/PAL formats, displays satellite info, and is accurate to 1
ms of UTC. These units are now manufactured and sold by PFD Systems, LLC in
The price of this unit ready to go and
assembled is $150. It requires a Garmin 18 LVC GPS receiver for an additional
$85 plus shipping/handling.
McAfee VTI: Don McAfee (e-mail dmcafee@mcafeescientific.com)
designed a box unit fully assembled which displays GPS time to 0.001 second,
plus LAT/LONG, ALT and date info all for about $285 ready to go. Like the Kiwi
OSD, it uses the Garmin 18 LVC GPS receiver which has a built in magnet to
attach to a convenient location. This VTI also has a toggle switch to go back
and forth from position info to time. The time displays a single time to 0.001
sec unlike the Kiwi OSD which has half frame times displayed. The McAfee unit
also uses a built in quartz clock to keep the time displayed in case of loss of
signal. McAfee has made only a few of these units, not having the larger
manufacturing capacity of PFD Systems for the Kiwi unit.
ViTi and GHS Clock: This unit is designed and sold in
Hans-Hellmuth Cuno gave a talk at the
European Symposium on Occultation Projects (ESOP) about a GPS time inserter he
built. Details can be found at http://www.astronik.de.
Derek Breit suggested setting up a GPS unit early for an
occultation to allow almanac data to download to your particular receiver. This
helps prevent time errors which have been known to deviate from WWV by as much as
10 seconds, either when satellite geometry is poor due to local obstructions or
during the early acquisition before the GPS solution has had time to stabilize;
this usually takes 5 minutes or more.
David
Dunham showed some slides for the
pre-pointing method. The basic concept of this method is to have telescope
stations already set up and pointed in the direction that the target star will
be at the predicted time, allowing a non-specialist to record the occultation
since the pointing can be done hours in advance. The pre-pointing is made to a
star field at the same declination as the target star, with a right ascension
difference equal to the time difference to the event, taking into account the
10-seconds/hour difference between sidereal and mean solar rates. The
non-specialist will have to do only a few simple tasks to get the system
operational for the occultation, such as: a) setting an alarm to wake up, b)
taking the cover off the end of the telescope tube, c) reconnect any batteries,
d) turn on the timing device (WWV shortwave), e) press the "record"
button on the VCR/camcorder. f) stop the recording after the event. With the
non-specialist working the pre-pointed telescope system, the specialist drives
to another location to set up another station. If time permits, two or more
telescopes at different locations can be pre-pointed. The basic idea was
developed for remote (unattended) stations, but it has other applications,
helping those who can’t find target stars to obtain observations. The pre-pointing
should be timed to an accuracy of about 10 seconds, which can easily be
obtained with inexpensive self-setting "atomic" clocks that use WWVB
or DCF long-wave time signals. The technique can be used for visual as well as
video observations. Dunham first used the technique in 1965 for a visual
observation of a daytime partial occultation of Jupiter by the Moon when both
objects were too close to the Sun to see without telescopic aid.
Vice President Paul Maley talked about his rating method for advertising
asteroid occultations in the
Maley’s ratings are:
X = eXtra special/don’t miss it =5
PG = Pretty Good =4
G = Give it a shot =3
M = Maybe worth trying =2
R = Ridiculous but not impossible =1
An "X" rated example event for this
system for the
Kazuhisa Miyashita in
http://www05.upp.so-net.ne.jp/k_miyash/occ02/limovie_en.html
David Dunham gave a few tips on finding the target star for
asteroid events using a GO TO telescope based originally on Walt Morgan’s
on-line article. The preferred finderscope is a straight thru type, except for
stars near the zenith when a right angle finder is easier to use. When the GOTO
scope is moving toward the target star check carefully that you have the
correct field. This might involve moving/inverting/flipping your star chart to
identify the field. Some GOTO scopes allow the user to jump to bright stars
when moving toward a target area. A synchronization key can be used to minimize
errors in pointing as the telescope moves closer to the target star. This
reduces the propagation of errors as the telescope slews across the sky. Morgan
prefers the Starry Night Pro to create finder charts, Dunham prefers the
Millennium and/or Herald-Bobroff Atlases. The various planetarium programs such
The Sky, MegaStar, SkyMap, etc. have a rectangle that can be overlaid onto the
FOV simplifying the identification of video fields.
Problems can occur with a GOTO telescope
system. Don’t assume that just because you push a few buttons that you are dead
on the target star. Alignment star errors, the amount of slewing distance, and
other factors can affect your GOTO accuracy. Bob Sandy commented that a dry run
is useful 2 or 3 days before the event. A practice session can help identify
unforeseen problems. The lesson here is to learn your own system.
David Dunham discussed how to use predictions
and profiles to find observing sites for grazing occultations. The Tan Z
correction and limit correction were plotted on the 1:125,000 scale Delorme’s
Street Atlas USA Version 8. Dunham mentioned some important considerations
about using graze predictions: The Tan Z correction can usually be ignored for
elevations less than 750 feet above mean sea level since it is so small, and
graze profiles change when stations are more than 100-200km along the limit
line. Unlike asteroid events, in which the asteroids are relatively small and
far away, the Moon’s profile changes slightly due to its proximity to Earth.
Dunham spoke about the southern-limit graze he attempted
last December 17, 2004 of m = 7.5 ZC 3434 at Valley
Wayne Warren had attempted to observe this graze with Dunham, however he didn’t make it through the rush hour traffic in time and wasn’t able to start observing until just after the graze ended! David Dunham has made the record book again: this event marked the first graze profile entirely determined by a single observer operating 3 stations. He actually did even better during the graze of tau Aquarii on December 21, 2001 at Kitty Hawk, NC when he recorded that graze from 4 widely-separated stations (3 remote video stations), but 9 other observers also timed the multiple events during that graze.
On the topic of grazing occultations for
2005, several videos of the more favorable ones were shown: Kerry Coughlin’s
video of Antares from Baja California on March 3, and Ed Morana’s and Derek
Breit’s videos of Upsilon Gem on April 18 (m = 4.1 star). This event had
9 stations and 15 observers. Dunham recorded a graze of Tau Ari (m =
5.0) on March 15 with a 30% Moon from 3 stations in clear cold skies in
The best graze of the year was of the 1st
magnitude star Antares on July 18. Dunham showed graze profiles obtained from
expeditions from Washington State/Utah,
Bob Sandy then showed the reduction profile
of the Aldebaran graze from September 12, 1998 from
Following a short break Bob Sandy showed some
color slides; the first one of the planet Venus after it reappeared from
behind the 33% sunlit Moon on 26 December, 1978. This is the same shot as
the picture at the heading of his web site. Then he showed a slide
sequence of Jupiter, and its four brighter moons being occulted by the Moon.
The Moon/Venus occultation slide is the one used on the IOTA baseball cap.
David
Dunham continued the meeting with a
status report on his (and Wayne Warren’s) long-term effort in IOTA’s solar
radius experiment and research. Dunham had presented the results of his
research at the 2005 SORCE (SOlar Radiation and Climate Experiment, a NASA
satellite launched in 2003) Science Meeting September 14-15, in
Videos of Baily’s Beads obtained during the
eclipses of 1991, 1994, 1995, 1998, 1999 and 2002 were analyzed in part with
David Herald’s Baily’s Bead module of the program OCCULT. James Thompson, a
NASA summer mentor student, performed most of the work under Dunham’s
supervision. The results indicate solar radius changes varying from 0.06¢ ¢ ± 0.06¢
¢ (Aug 11, 1999 eclipse) to -0.27¢ ¢ ± 0.02¢ ¢ (May 1994 eclipse). A plot of
the solar radius changes didn’t show any obvious trend, however this doesn’t
prove that there isn’t a cycle of small scale solar radius changes occurring
with the Sun.
One of the nagging issues in this research is
the criticism of the lack of standardization of equipment used for the Baily’s
Bead’s videos. Different telescope systems and different solar filters were
used at each of the eclipses studied and this may be partly responsible for the
inconsistent results. Different filters allow different maximum wavelength
transmissions of the Sun’s light to be analyzed possibly affecting the Bead
timings. Dunham suggested that Richard Nugent’s compact 4-inch telescope system
with
Roger Venable suggested testing all equipment
and combinations side by side at the next solar eclipse. The videos/bead timings
can be analyzed for any type of variation or systematic errors. Along these
lines, Sandy Bumgarner suggested using remote stations for testing/comparing
the equipment. Maley cautioned that although in principle this sounds simple
enough, there are unstable conditions beyond the observer’s control such as
dust storms, wind, tampering/theft of equipment, etc. More study is needed and
the funding of this research has an additional year to go; a final paper is
planned for publication.
Paul Maley discussed his proposed Project Blind Squirrel, a
concept for intercepting asteroid occultations and asteroid companions. The
concept is to provide a deployable portable system of 8-inch telescopes for
asteroid occultation intercepts. Several telescope systems were discussed, that
have been nicknamed TOTO=totable occultation tracking optics. Maley commended
Dunham and Venable who have used multiple stations to achieve success but
believes that to get better results the adage "more is better" should
be applied.
The portable systems (approximately 10-15)
would be deployed at intervals along a road for an asteroid event, the actual
locations to be defined by the occultation. The systems would be required to
have a simple quick setup (15 minutes) and be automated to record the
occultation event. Control of the telescope systems could be automated/robotic,
done via the internet or some other wireless method. One possible lower cost
(~$500) system would consist of an Orion portable table top mount, 50 mm
telephoto lens suitable only for 7th mag or brighter stars, and a Supercircuits
PC164 camera.
The advantages of this method are to increase
the probability to intercept occultations and increase the chances to detect
and confirm an asteroid satellite. Funding is needed to implement such a
system; so far, IOTA has received no support for this work.
David Dunham briefed the attendees about an
ESOP 2005 (European Symposium on Occultation Projects) presentation by Wofgang
Beisker on The Dual Wavelength Occultation Camera. This camera shoots the
occultation simultaneously at two wavelengths using dichroic mirrors, making it
is possible to record images in two or even more different wavelengths from a
single telescope without wasting light. This method was developed mainly for occultations
involving planets with atmospheres, but it could also be used to measure the
colors of components of binary stars occulted by the Moon or by asteroids.
Prior to
the close of the meeting, Danny Falla mentioned a Science News article for
August 13, 2005 that the asteroid 87 Sylvia now has confirmed 2 satellites. See
the Science News web announcement: http://www.sciencenews.org/articles/20050813/fob5.asp
The meeting was adjourned for the day at
6:15PM. The attendees proceeded to Art and Barbara Lucas’s house for a BBQ
dinner.
David Dunham began the meeting with a plan to
update all observed asteroid occultation events into the OCCULT program
historical observations database. There are over 700 observed asteroid
occultation observations with just 413 listed in version 3.0 of OCCULT. New
observed events are being made at the rate of about 2-3 per week. Sandy
Bumgarner asked if the reporting of asteroid events could be standardized into
a unique format so that the information could be loaded directly into the
OCCULT program database (by creating the .obs file). There is a web page
maintained by Jan Manek that allows observers to report asteroid events online.
2005 did not any have any spectacular
asteroid events observed with dozens of observers, but a few are worth
mentioning:
71
Niobe may have a large satellite when it occulted an 8th magnitude
star on February 10, 2005. The occultation was observed photoelectrically by Bob
Cadmus at Grinnell College Observatory,
54 Alexandra was timed by 15 stations on May
17, 2005 in
89 Julia was observed by 7 stations on August
13, 2005. The resulting size came to 174.4 ± 5.8km x 135.6 ± 2.6km.
166 Rhodope by the 1st magnitude
star Regulus on October 19, 2005 (10 days before the IOTA meeting) over
Europe/Asia. This was a daylight event except for southern Europe;
Costantino Sigismondi led an expedition for
the Regulus event to
Another chance to see Regulus occulted is in
2014 March 20 by 163 Erigone over the northeast
Dunham mentioned a good tip for airline
travelers. He places a note in his suitcase with his equipment so that when the
TSA security officials randomly inspect his checked baggage, they can contact
him about the strange equipment on his cell phone. The note in the suitcase
idea is an excellent method to avoid a delay which could possibly cause his
baggage to be removed from the flight.
Paul
Maley discussed his efforts on random
asteroid satellite searches. Tom Van Flandern has calculated that an asteroidal
satellite can have a stable orbit at least up to 10 asteroid diameters from the
parent asteroid. Fueled by Maley’s own visual observation of a blink during the
asteroid occultation event of (6) Hebe in March 1977 while he was far outside
the occultation path, and other observations/photographs of asteroid
satellites, Maley has attempted to observe all occultations where he was within
1,000 miles of the path from 1977 to the present. In all he has attempted over
800 such appulses, 80 of them alone in the first 6 months of 2003, with 43
successes overall. Maley has a supporting database of observers in
A brief discussion continued on the possible
methods of detecting asteroidal satellites and the theory of their origin,
including the impacts and the approximate distance from the parent asteroid. In
order to confirm an asteroid moon, IOTA needs observers separated by no more
than 2-3 km, since these objects are typically expected to be relatively small
compared to the primary.
Possible solutions to help IOTA confirm an
asteroidal satellite are:
1) Need more remote stations
2) Two (or more) nearly co-located sites less
than 5 km apart to confirm the short
occultations caused by satellites
Maley believes that for a single person
attempting to provide confirmatory evidence of an asteroid satellite one
approach is to place one video/and one visual < 5km to 5 meters apart. In
this way it is easier for one person to control and support two stations and
maintain their integrity.
Along this discussion, Sandy Bumgarner said
that the popular Collins I3 image intensifier may not be available for sale to
individuals due to large government orders of the basic tube for the
Following a short break Dunham recapped the
observations made earlier on Saturday morning by 790
Dunham mentioned there are a few good grazes
left in 2005:
25 November 2005: σ Leo from
23 December 2005: β Vir ( m =
5.0) from
25 December 2005: 1st magnitude
Spica from
26 December 2005: Eta Vir,
In 2006 no observable 1st magnitude
star grazes occur over the
With some occultations at or near daylight
conditions, Roger Venable suggested using an infrared filter to increase the
contrast to aid in observing the event.
Remaining good asteroid events for 2005:
15 November: 345 Tercidina, m = 8.9 star
2 December: 52 Europa,
3 January 2006: 598 Octavia, m = 10.0 star
in Gemini
28 January 2006: 490 Veritas, m = 10.0
star in Orion
16 February 2006: 71 Niobe, South Florida to
from occultation observations as mentioned
earlier. This is a good one to watch.
21 February 2006: The Mars moon Deimos will
occult a m = 9.0 star
24 February 2006: 530 Turandot, m =
7.9 star, northeast
12 April 2006: 305 Gordonia (50km size)
occults λ Vir, a m = 4.6 star over southern
and
5 May 2006: 7 Iris, occults HIP 116495, m
= 5.8 over the northeast
6 May 2006: 762 Pulcova, m = 11.9 star
in a north south path from
David Dunham said Adirondak Video now markets
an occultation video package which consists of a Supercircuits PC-164 camera
and adapters for about $170.
From the web, ON editor John Graves wrote in
that possibly several times per year, we could have a webcast to pursue online
discussions. This would be a useful way to prepare for important occultation
events and other IOTA matters. Needless to say, verbal communications are often
more effective at getting things done than the usual emails.
Following this a few videos were shown of the
The meeting adjourned at 12:53 PM and the
attendees continued their informal discussions.
Most of the presentation files for this
meeting are at http://iota.jhuapl.edu/2005iota.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.