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Six positive chords were recorded for this event. Well done team!
View the updated prediction.
Observers: 1 J Bradshaw,Samford, QLD, AU - Video 2 P Anderson,Taylor Range Obs,QLD,AU - Visual 3 J Broughton,Reedy Creek, QLD, AUS - Visual - 1 sec taken off times to get data to align with others 4 J Broughton,Reedy Creek, QLD , AU - Drift scan 5 S Kerr,Duaringa, QLD, AU - Video w.audio time signal - 1.5 secs taken off as Steve noted problems with absolute time but was confident of duration 6 S Kerr,Dingo, Queensland, Australia - Video 7(P) Prediction 24 May 8(M) D Breadsell,Toowoomba,QLD,AU - Visual - It looks like David was about 10-15 km too far south.
Discussion:
The elippse above is plotted at the Best fir to the adjusted chords measured for Irmintraud. With six chords we can have high confidence in the location of the event. It appears that the path was about 40 km North of the prediction.
The figure below shows the drift-scan image of the occultation as observed by John Broughton.
The figures below show the Limovie Plots for Steve Kerr's two observations.
The figure below shows the Limovie Plots for Jonathan Bradshaw's observation.
Observational Data:
Observation details for MP (773 ) Irmintraud By Star TYC 8342-00113-1 On 2008-06-24 at 09:06:58.0 _______________________________ Observer John Broughton Location Reedy Creek, QLD, AU Longitude +153:20:41.8 Latitude -28:11:58. Altitude 60 m Datum WGS84 Telescope SCT Aperture 25 cm Seeing Steady Clear Timing Tape Recorder + time signal Visual, PE applied Disappearance 09:06:58.94 Reappearance 09:07:06.50 Comments: This was my first attempt at a mobile sighting of an asteroid occultation, first positive visual, and with a drift scan going on at home, my first double positive. The altazimuth SCT was on a round wooden base low to the ground. I used manual altazimuth prepointing to set up a drift-through observation. Apart from being a very simple telescope setup and alignment method, there is the advantage of not needing to check the time once the star has entered the field, knowing that the predicted time occurs when the star crosses center. Voice audio and a ticking clock reference was recorded on a digital camera's sound recorder and later calibrated to UTC. That was the backup timing method, after finding the SW signal to be too faint at the site. One minor mistake was to end the observing only 20s after reappearance. _______________________________ Observer John Broughton Location Reedy Creek, QLD, AU Longitude +153:23:52.8 Latitude -28:06:30.3 Altitude 66 m Datum WGS84 Telescope Newtonian Aperture 51 cm Seeing Steady Clear Timing Tape Recorder + time signal + shutter Drift scan Disappearance 09:07:00.09 Reappearance 09:07:07.60 Comments: This was my first unattended drift-scan observation, the telescope having been prepointed on the previous night. The exposure was on a 3-hour delay; Maxim DL can take delayed images of up to 32767s (9.1h) and Scantracker supports that. The tape recorder was operated by a powerpoint timer and an alarm went off at 09:09:00 to establish integer second times. Established methods were used to record and derive the sub-second times. _______________________________ Observer Peter Anderson Location Taylor Range Obs,QLD,AU Longitude +152:55:54. Latitude -27:27:48. Altitude 176 m Datum Other Telescope Newtonian Aperture 41 cm Seeing Slight flickering Clear Timing Tape Recorder + time signal Visual, PE applied Disappearance 09:07:04.40 Reappearance 09:07:11.80 Comments: After reappearance the star appeared fainter and flickered until 09hrs 07min 30sec with futher atmospherics later till 09hrs 10min. Though atmospherics are the likely cause it was worthy of note. _______________________________ Observer Jonathan Bradshaw, Alison Beck Location Samford, QLD, AU Longitude +152:52:22.7 Latitude -27:21:22.8 Altitude 95 m Datum WGS84 Telescope Dobsonian Aperture 50 cm Seeing Steady Clear Timing GPS - time inserted Video with frame analysis Disappearance 09:07:05.32 Reappearance 09:07:12.60 Comments: Stunning event 20ms has been subtracted to account for camera latency - Gstar-ex @ 2x _______________________________ Observer Stephen Kerr Location Dingo, Queensland, Australia Longitude +149:20:7.5 Latitude -23:39:5.4 Altitude 120 m Datum WGS84 Telescope SCT including Cass and Mak Aperture 30 cm Seeing Steady Clear Timing GPS - time inserted Video with frame analysis Disappearance 09:07:36.31 Reappearance 09:07:43.11 Comments _______________________________ Observer Stephen Kerr Location Duaringa, QLD, AU Longitude +149:40:36.4 Latitude -23:44:21.3 Altitude 117 m Datum WGS84 Telescope Refractor Aperture 8 cm Seeing Steady Clear Timing Video + audio time signal Video with frame analysis Disappearance 09:07:36.00 Reappearance 09:07:43.56 CommentsVideo camera integrating at 120 millisecond interval. Time reference failed. Only event duration known with any accuracy. _______________________________ Observer David B Breadsell Location Toowoomba,QLD,AU Longitude +151:55:37.4 Latitude -27:35:58.4 Altitude 730 m Datum WGS84 Telescope Dobsonian Aperture 25 cm Seeing Steady Clear Timing Stopwatch Visual, PE applied Missed Comments: Good conditions. Certain that no occultation occurred. _______________________________ All in all a very good reult for the team.