A 6 second occultation was recorded by David Dunham, using an unattended video recording setup.

3 misses were recorded for this event.

View the IOTA update.

Observers:
  1(M) S Kerr,Rockhampton, Queensland, Australia
  2    D Dunham,Aileron, NT, Australia      
  3(M) D Dunham,Taylor Creek, NT, Australia 
  4(M) R Williamson,Connellon, NT, Australia
  5(P) Prediction- IOTA Feed                

         



       

Discussion:

The circle above is plotted at the expected 169 km diameter of Bertholda. As can be clearly seen in the graphics above, it is not possible to fit a 169km circle to the positive observation without overlapping reported misses. It should be noted that of the chords reported here, only Steve's (chord 1) was recorded with a tracking telescope - all of the others are prepointed and as such only cover the event for a short duration. However, the event time reported by David for his Aileron site does not significantly differ from the prediction and there is no reason to suspect that any of the other sites would have missed the event assuming they were aimed correctly (and the reports state that the correct field was imaged at the correct times).

(420) Bertholda has been extensively observed by occultation before with a very detailed profile recorded on 2003 August 26. The profile is plotted below. While this observation is dominated by visual observers, it clearly shows that (420) Bertholda is an oblong object.

If the dimensions from that observation are applied to the current observation, it can be shown that the miss observations can be accomodated. While it fits more easily on the northern side of the positive observation, it is possible that it could be on the southern side.

David and Joan Dunham had depoloyed a number of additional unattended stations along the Stuart Highway but suffered an unusual number of failures with equipment as well as interference - presumably from animals! It's dangerous in the Australian outback at night!

Observational Data:

Observation details for MP ( 420 ) Bertholda
By Star              TYC 6268-01114-1 
On 2015-07-31  at 10:20:17.0

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Observer   Stephen Kerr
Location   Rockhampton, Queensland, Australia
Longitude  +150:30
Latitude   -23:16
Altitude   50 m
Datum      Other
Telescope SCT including Cass and Mak
Aperture   30 cm
Seeing     Slight flickering Clear 
Camera Type  Watec 120N+    PAL/CCIR      
Camera Delay 
Timing     GPS - time inserted Video with frame analysis

Missed

Comments:   Report prepopulated by IOTA Reporting Add-in for OW ver.1.8

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Observer   David and Joan Dunham
Location   Aileron, NT, Australia
Longitude  +133:22
Latitude   -22:42
Altitude   662 m
Datum      WGS84
Telescope Refractor
Aperture    8 cm
Seeing     Steady Clear 
Camera Type  Other - List in Comments     NTSC/EIA      
Camera Delay 
Timing     GPS - other linking Video, photo or photoelectric
Disappearance  10:22:57.00
Reappearance   10:23:03.00
Comments: Remote unattended pre-pointed station using a KPC-650-BH? (NTSC) camera, "Supercircuits PC164C-EX2". Recorded with Canon ZR60 #37. Used a paver and paver mount to pre-point the scope the night before. Left the paver in place, returned with scope & mount July 31.  -109km(s) of pred. center. IOTA-VTI pre-cal 5:05UT (event -5.3h), post-cal 14:00UT (event +3.6h);  .avi files being uploaded to IOTA Dropbox folder.

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Observer   David and Joan Dunham
Location   Taylor Creek, NT, Australia
Longitude  +134:09
Latitude   -21:08
Altitude   417 m
Datum      WGS84
Telescope Refractor
Aperture   12 cm
Seeing     Steady Clear 
Camera Type  Other - List in Comments     NTSC/EIA      
Camera Delay 
Timing     GPS - time inserted Video, photo or photoelectric

Missed

Comments: Remote unattended pre-pointed station using a KPC-650-BH? (NTSC) camera, "Supercircuits PC164C-EX2".  Pre-pointed at 9:02 UT (event -1.4h) and recorder left recording. 

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Observer   Richard Williamson
Location   Connellon, NT, Australia
Longitude  +133:54
Latitude   -23:46
Altitude   550 m
Datum      WGS84
Telescope SCT including Cass and Mak
Aperture   20 cm
Seeing     Steady Clear 
Camera Type  Watec 120N+    PAL/CCIR      
Camera Delay 
Timing     GPS - time inserted Video, photo or photoelectric

Missed

Comments: No integration was used. Pre-pointed before the occultation.