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OCCULTATION OF TYC 8342-00113-1 BY 773 Irmintraud
2008 June 24


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.

Irmintraud occultation - 2008 June 24

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.

Irmintraud occultation - 2008 June 24

The figures below show the Limovie Plots for Steve Kerr's two observations.

Irmintraud occultation - 2008 June 24

The figure below shows the Limovie Plots for Jonathan Bradshaw's observation.

Irmintraud occultation - 2008 June 24

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. 

Return to 2008 occultation results



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