Hiraoka Occultation Pushing the limits on what a backyard observer can do with modest amateur equipment By Tony George Umatilla, Oregon

Background Observing occultations for 20 years Observing occultations for 20 years In 20 years I have contributed 8 positive observations In 20 years I have contributed 8 positive observations While I attempt to observe every possible event, good opportunities in the Pacific Northwest are few and far between. While I attempt to observe every possible event, good opportunities in the Pacific Northwest are few and far between. To keep in practice, I often try to observe occultations of asteroids as small as 4 km in size To keep in practice, I often try to observe occultations of asteroids as small as 4 km in size

Methodology Once every few months I run an updated prediction of occultations visible from my home site using WinOccult developed by David Herald of Australia Once every few months I run an updated prediction of occultations visible from my home site using WinOccult developed by David Herald of Australia I select all numbered asteroids larger than 4 km in size I select all numbered asteroids larger than 4 km in size I select all occultation paths that are within 50 km of my home site I select all occultation paths that are within 50 km of my home site

Equipment Meade LX200GPS 12-inch telescope Meade LX200GPS 12-inch telescope Meade f3.3 focal reducer Meade f3.3 focal reducer WAT 902H2 Ultimate or Supercircuits PC164C security video camera WAT 902H2 Ultimate or Supercircuits PC164C security video camera STV Astro (or KIWI OSD) GPS video time inserter STV Astro (or KIWI OSD) GPS video time inserter Garmin 16 GPS receiver (or Garmin 18 with KIWI OSD) Garmin 16 GPS receiver (or Garmin 18 with KIWI OSD) Canon ZR50 Mini DV tape recorder Canon ZR50 Mini DV tape recorder Battery pack Battery pack

Photo of 12-inch LX200GPS Equipment Canon ZR50 Mini DVR Garmin GPS16 Receiver WAT 902H2 Ultimate Video Camera w/manual Gain control (can also use Supercircuits PC164C or CCD camera in drift scan Mode) STV Astro video time inserter (most now use KIWI OSD) 12V DC Battery pack Meade f3.3 focal reducer

Hiraoka Predicted Occultation

Hiraoka Predicted Path

Hiraoka Occultation Target Star Hiraoka Star Field as seen by PC164C video camera

Hiraoka Star Field Oriented to N-S

Digitized Sky Survey photo of star field

TheSky6 planetarium program view of star field

Hiraoka Observation Began recording 3 minutes before predicted time of event Began recording 3 minutes before predicted time of event Recorded until 3 minutes after event Recorded until 3 minutes after event Due to predicted max duration of 0.2 seconds, the occultation was not visible to the eye when reviewing the video tape Due to predicted max duration of 0.2 seconds, the occultation was not visible to the eye when reviewing the video tape

Here is how it looked ….

LiMovie to the rescue! I used LiMovie a new video analysis tool to analyze the video and find the extremely short occultation

LiMovie Plot of target star intensity over time period when occultation occurred

Extraordinary claims require extraordinary proof…. The claim to see a 0.2 second occultation is very extraordinary The claim to see a 0.2 second occultation is very extraordinary While LiMovie plot shows a likely occultation, the noise in the data might also be the cause of the extended drop in light intensity While LiMovie plot shows a likely occultation, the noise in the data might also be the cause of the extended drop in light intensity Comparisons to the other two field stars did not show any similar drop in light intensity Comparisons to the other two field stars did not show any similar drop in light intensity An outside independent analyst volunteered to review the data to determine if an occultation occurred An outside independent analyst volunteered to review the data to determine if an occultation occurred

An independent analysis of my report was conducted by Dr. Michael Richmond of the Dept. of Physics Rochester Institute of Technology Here is a link to his webpage documenting his analysis: His conclusion: I agree with Tony's conclusion: the asteroid occulted the star for 7 frames, which is equivalent to 14 fields.

Based on the data provided and the independent analysis by Dr. Michael Richmond Dave Herald of IOTA accepted the data for submission to the Minor Planet Center (MPC) – this is the shortest single-chord event ever submitted to the MPC

Final Data Submitted Occultation Duration 0.20 seconds Occultation Duration 0.20 seconds Calculated Diameter of the Asteroid = 7 km – assuming the widest part of the asteroid caused the occultation seen Calculated Diameter of the Asteroid = 7 km – assuming the widest part of the asteroid caused the occultation seen

When the results were shared with the LiMovie author, I Received Japanese Comments Regarding the Hiraoka Observation: Yoshihiro Yamada who is the discoverer of the Hiraoka asteroid wrote: I am very glad to know this. Because it is the first success observation of the asteroids which is discovered by me. Yoshihiro Yamada who is the discoverer of the Hiraoka asteroid wrote: I am very glad to know this. Because it is the first success observation of the asteroids which is discovered by me. Tsutomu Hayamizu, who is the one of the coordinators of asteroid's occultation in Japan, wrote: I ask you to inform him "Congratulation on your observation success!" Only 14 fields.. I think we are entering a new era of occultation observation. And we learned many things from his preparation and his observation. Tsutomu Hayamizu, who is the one of the coordinators of asteroid's occultation in Japan, wrote: I ask you to inform him "Congratulation on your observation success!" Only 14 fields.. I think we are entering a new era of occultation observation. And we learned many things from his preparation and his observation. Hiromi Hamanowa, the most successful observer of asteroidal occultations in Japan wrote: Great work! It seems distinctly the light curve different from the one which is influence by air scintillation. It shows us how to use Limovie at its best performance. Highly accurate orbital element will be obtained from only one observation. I think this to be extremely meaningful observation. I entertain a profound respect for Tony's spirit and his effort. Hiromi Hamanowa, the most successful observer of asteroidal occultations in Japan wrote: Great work! It seems distinctly the light curve different from the one which is influence by air scintillation. It shows us how to use Limovie at its best performance. Highly accurate orbital element will be obtained from only one observation. I think this to be extremely meaningful observation. I entertain a profound respect for Tony's spirit and his effort.

We are just beginning to stretch the limits of what can be done with modest amateur equipment. As video cameras are improved we can observe events involving fainter stars In the future, we should be observing occultations by trans-Neptunian objects (TNOs) – those diminutive objects out in the Kuiper belt beyond the orbit of Neptune. We may also contribute vital information on the size and shape of Near Earth Objects (NEOs) that someday may be a hazard to the Earth. The Future of Occultations