Welcome to the International Occultation Timing Association 2010 November 17 IOTA/Middle East Conference David W. Dunham, President, IOTA.

Welcome to the International Occultation

Timing Association

2010 November 17IOTA/Middle East Conference

David W. Dunham, President, IOTA

74 attended the IOTA-ME workshopin Gonbad, Iran Nov. 17, 2010, thelargest IOTA meeting ever, I believe

The Middle East is a special place for me –I became interested in astronomy in 1955 when I was 11 years old while living under mostly clear skies in the desert climate of Karachi, Pakistan. My father was a civil engineer who worked for two years on the design for a modern fish harbor for the then capital of Pakistan. I was amazed one day to see the names of over 250 stars, most with Arabic names, in a large dictionary – I wanted to find all of them in the sky. I self-taught myself the constellations, and as we traveled across Europe back to the United States in 1956, I saw that the same constellations were visible from all lands (of course, depending on latitude) and knew that I would remember them for the rest of my life.

Karachi

Perhaps the Pakistani flag, with its Islamic crescent Moon and star, looking like a spectacular occulta-tion, was a premonition of what would become my interest in these events.

Southern Limit of the 2 Capricorni

Occultation in California, 1957 October 29

ME

When I was 15 years old, I almost saw this grazing occultation, but they weren’t predicted then. I thought it would be neat if someone could predict graze lines so that one could travel to them, but at that age, I thought I would not be able to do that. Five years later, after learning much more math and astronomy, I wrote the first computer program to calculate graze paths. Dave Gault will tell you more of the history of IOTA in his presentation.

The First Unattended Stations were Deployed for Grazing Occultations

• During the 1980’s, I acquired video equipment and began video recording occultations and grazes.

• In the 1990’s, I often thought, the equipment is doing all the work, maybe I should be somewhere else making another observation.

• For a graze of omicron Leonis the morning of 1998 November 12, I set up a 5-in. clock-driven SCT at Delta, Pennsylvania, near York

• I left a student there after showing him how to make adjustments to keep the star in the field of view, and set up another telescope about 0.5 km away to record the event

• When I came back, he was excited to see the multiple occultations of the star. “Did you make any adjustments?” “No”. “At least, you were there to protect the equipment”.

• “Actually, it was the other way around. Whenever a car drove by, I hid behind the telescope box.”

Remote Stations for Asteroidal Occultations• Separation should be many km, much larger than for grazes, so tracking times &

errors are too large• Unguided is possible since the prediction times are accurate enough, to less that

1 min. = ¼• Point telescope beforehand to same altitude and azimuth that the target star will

have at event time and keep it fixed in that direction• Plot line of target star’s declination on a detailed star atlas; I use the Millennium

Atlas (the charts are now made with Guide 8 software)• From the RA difference and event time for the area of observation, calculate

times along the declination line• Adjust the above for sidereal rate that is faster than solar rate, add 10 seconds

for each hour before the event• Can usually find “guide stars” that are easier to find than the target• This technique is useful for ALL observers of asteroidal occultations• Find a safe but accessible place for both the attended & remote scopes• Separation distance limited by travel time & maximum tape record time• Equipment that allows timed starts allows larger station separations• When possible, it is better to have remote sites attended for starting equipment

later (allows larger separations) and security

Example of a close double star, 9th-mag. SAO 58354, whose occultation I recorded from three stations in December 2005

More about this event, including the video files, is at http://iota.jhuapl.edu/mp099.htm - the step events are clear in the northern (Greenbelt) video

A portable setup to observe a lunar grazing occultation (or asteroidal occultation) from a location far from home. One can spend much time and

resources on equipment to make interesting occultation observations, but the important thing is to go out and observe what you can with the telescope and

equipment that you have.

Scotty Degenhardt’s “portable” setup to remotely observe the lunar grazing occultation of Regulus on November 3, 2007.

Toooooo much stuff!

Thus began his quest to miniaturize…

The simple optical systems described above

• might be used by visual observers, too.• If many observers can be mobilized, the video cameras can be

replaced with eyepieces and observers at each station, if video cameras and video recorders are not available.

• Then, small digital audio recorders can record voiced call-outs of the events and short-wave time signals, such as the Russian and Chinese short-wave signals at 5, 10, and 15 megahertz

• If audio recorders are not available, an assistant can look at a stopwatch (started and stopped at short-wave time signal minute tones; just one short-wave radio is needed on a graze expedition, with the stopwatch started 10 to 20 minutes before and after the graze) and write down the time of called-out events.

• Use whatever equipment is available• Most important is to observe lunar grazing occultations and

asteroidal occultations from as many locations as possible.

Locations of 1999 Leonids Lunar Impactsthat I recorded Nov. 18 with 13cm telescope at Mt. Airy, MD

The green dots markimpact flashes that were confirmed byother IOTA observersat distant locations.

These were the firstconfirmed lunarmeteor impactflashes; video recording these illusive events isanother IOTAactivity.

Leonid Lunar ImpactRecorded 2001 Nov. 18, 23:19:15 UT, Laurel, MD

confirmed by Tony Cook at Arlington, VAand Roger Venable, Augusta, GA

Conclusions

• Welcome to IOTA and the interesting occultation phenomena that we observe

• New discoveries (new close double stars, lunar profile information, asteroid outlines, etc.) await your observations

• Good luck with your observations!