Hiraoka OccultationHiraoka Occultation

Pushing the limits on what a Pushing the limits on what a backyard observer can do with backyard observer can do with

modest amateur equipmentmodest amateur equipment

By Tony GeorgeBy Tony George

Umatilla, OregonUmatilla, Oregon

BackgroundBackground

Observing occultations for 20 yearsObserving occultations for 20 years In 20 years I have contributed 8 positive In 20 years I have contributed 8 positive

observationsobservationsWhile I attempt to observe every possible While I attempt to observe every possible

event, good opportunities in the Pacific event, good opportunities in the Pacific Northwest are few and far between. Northwest are few and far between.

To keep in practice, I often try to observe To keep in practice, I often try to observe occultations of asteroids as small as 4 km occultations of asteroids as small as 4 km in sizein size

MethodologyMethodology

Once every few months I run an updated Once every few months I run an updated prediction of occultations visible from my prediction of occultations visible from my home site using WinOccult developed by home site using WinOccult developed by David Herald of AustraliaDavid Herald of Australia

I select all numbered asteroids larger than I select all numbered asteroids larger than 4 km in size4 km in size

I select all occultation paths that are within I select all occultation paths that are within 50 km of my home site50 km of my home site

EquipmentEquipment

Meade LX200GPS 12-inch telescopeMeade LX200GPS 12-inch telescope Meade f3.3 focal reducerMeade f3.3 focal reducer WAT 902H2 Ultimate or Supercircuits PC164C WAT 902H2 Ultimate or Supercircuits PC164C

security video camerasecurity video camera STV Astro (or KIWI OSD) GPS video time STV Astro (or KIWI OSD) GPS video time

inserterinserter Garmin 16 GPS receiver (or Garmin 18 with Garmin 16 GPS receiver (or Garmin 18 with

KIWI OSD)KIWI OSD) Canon ZR50 Mini DV tape recorderCanon ZR50 Mini DV tape recorder Battery packBattery pack

Photo of 12-inch Photo of 12-inch LX200GPS EquipmentLX200GPS Equipment

Canon ZR50 Mini DVR

Garmin GPS16 Receiver

WAT 902H2 UltimateVideo Camera w/manualGain control (can also useSupercircuits PC164C or CCD camera in drift scanMode)

STV Astro video time inserter (most now use KIWI OSD)

12V DC Battery pack

Meade f3.3 focal reducer

Hiraoka Predicted OccultationHiraoka Predicted Occultation

Hiraoka Predicted PathHiraoka Predicted Path

Hiraoka OccultationTarget Star

Hiraoka Star Field as seen by Hiraoka Star Field as seen by PC164C video cameraPC164C video camera

Hiraoka Star Hiraoka Star Field Oriented Field Oriented

to N-Sto N-S

Digitized Digitized Sky Sky

Survey Survey photo of photo of star fieldstar field

TheSky6 planetarium program view of star fieldTheSky6 planetarium program view of star field

Hiraoka ObservationHiraoka Observation

Began recording 3 minutes before Began recording 3 minutes before predicted time of eventpredicted time of event

Recorded until 3 minutes after eventRecorded until 3 minutes after eventDue to predicted max duration of 0.2 Due to predicted max duration of 0.2

seconds, the occultation was not visible to seconds, the occultation was not visible to the eye when reviewing the video tapethe eye when reviewing the video tape

Here is how it looked ….Here is how it looked ….

LiMovie to the rescue! LiMovie to the rescue!

I used LiMovie a new video analysis I used LiMovie a new video analysis tool to analyze the video and find the tool to analyze the video and find the

extremely short occultation extremely short occultation

Target Star Only -- Raw Data and Moving Average Data

0

500

1000

1500

2000

2500

3000

3500

1 144 287 430 573 716 859 1002 1145 1288 1431 1574 1717 1860 2003 2146 2289 2432 2575 2718 2861 3004 3147 3290 3433 3576

Target Star LiMovie Aperture Data 10 per. Mov. Avg. (Target Star LiMovie Aperture Data)

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

Extraordinary claims require Extraordinary claims require extraordinary proof….extraordinary proof….

The claim to see a 0.2 second occultation is very The claim to see a 0.2 second occultation is very extraordinaryextraordinary

While LiMovie plot shows a likely occultation, the While LiMovie plot shows a likely occultation, the noise in the data might also be the cause of the noise in the data might also be the cause of the extended drop in light intensityextended drop in light intensity

Comparisons to the other two field stars did not Comparisons to the other two field stars did not show any similar drop in light intensityshow any similar drop in light intensity

An outside independent analyst volunteered to An outside independent analyst volunteered to review the data to determine if an occultation review the data to determine if an occultation occurredoccurred

An independent analysis of my report was An independent analysis of my report was conducted by Dr. Michael Richmond of conducted by Dr. Michael Richmond of

the Dept. of Physics Rochester Institute of the Dept. of Physics Rochester Institute of Technology Technology

Here is a link to his webpage documenting his analysis:Here is a link to his webpage documenting his analysis:

http://spiff.rit.edu/richmond/occult/hiraoka_may2006/hiraoka_may2006.htmlhttp://spiff.rit.edu/richmond/occult/hiraoka_may2006/hiraoka_may2006.html

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 Based on the data provided and the independent analysis by independent analysis by

Dr. Michael RichmondDr. Michael Richmond

Dave Herald of IOTA accepted the Dave Herald of IOTA accepted the data for submission to the Minor data for submission to the Minor Planet Center (MPC) – this is the Planet Center (MPC) – this is the shortest single-chord event ever shortest single-chord event ever

submitted to the MPCsubmitted to the MPC

Final Data SubmittedFinal Data Submitted Occultation Duration Occultation Duration

0.20 seconds0.20 seconds Calculated Diameter of Calculated Diameter of

the Asteroid = 7 km – the Asteroid = 7 km – assuming the widest assuming the widest part of the asteroid part of the asteroid caused the occultation caused the occultation seenseen

When the results were shared with the LiMovie When the results were shared with the LiMovie author, I Received Japanese Comments author, I Received Japanese Comments

Regarding the Hiraoka Observation:Regarding the Hiraoka Observation:

Yoshihiro Yamada who is the discoverer of the Hiraoka asteroid wrote: Yoshihiro Yamada who is the discoverer of the Hiraoka asteroid wrote: I am very glad to know this. Because it is the first success I am very glad to know this. Because it is the first success observation of the asteroids which is discovered by me. observation of the asteroids which is discovered by me.

Tsutomu Hayamizu , who is the one of the coordinators of asteroid's Tsutomu Hayamizu , who is the one of the coordinators of asteroid's occultation in Japan, wrote: occultation in Japan, wrote: I ask you to inform him "Congratulation I ask you to inform him "Congratulation on your observation success!" Only 14 fields.. I think we are entering a on your observation success!" Only 14 fields.. I think we are entering a new era of occultation observation. And we learned many things from new era of occultation observation. And we learned many things from his preparation and his observation.his preparation and his observation.

Hiromi Hamanowa, the most successful observer of asteroidal Hiromi Hamanowa, the most successful observer of asteroidal occultations in Japan wrote: occultations in Japan wrote: Great work! It seems distinctly the light Great work! It seems distinctly the light curve different from the one which is influence by air scintillation. It curve different from the one which is influence by air scintillation. It shows us how to use Limovie at its best performance. Highly accurate shows us how to use Limovie at its best performance. Highly accurate orbital element will be obtained from only one observation. I think this orbital element will be obtained from only one observation. I think this to be extremely meaningful observation. I entertain a profound respect to be extremely meaningful observation. I entertain a profound respect for Tony's spirit and his effort.for Tony's spirit and his effort.

We are just beginning to stretch the limits of what can be We are just beginning to stretch the limits of what can be done with modest amateur equipment. As video cameras done with modest amateur equipment. As video cameras are improved we can observe events involving fainter are improved we can observe events involving fainter starsstars

In the future, we should be observing occultations by In the future, we should be observing occultations by trans-Neptunian objects (TNO’s) – those diminutive trans-Neptunian objects (TNO’s) – those diminutive objects out in the Kuiper belt beyond the orbit of Neptune. objects out in the Kuiper belt beyond the orbit of Neptune.

We may also contribute vital information on the size and We may also contribute vital information on the size and shape of Near Earth Objects (NEO’s) that someday may shape of Near Earth Objects (NEO’s) that someday may be a hazard to the Earth. be a hazard to the Earth.

The Future of Occultations The Future of Occultations