A 61.5 second occultation was recorded by Jonathan Bradshaw, using video OSD technique.

One indeterminate event was recorded by Bill Hanna for this event. For this report we will assume it was a miss.
and 5 stations were clouded out or had technical problems.

View the Felipe's prediction.

Observers:
  1    J Bradshaw,Samford Valley,QLD,AU
  2(M) W Hanna,Alice Springs, Australia
  3(P) Prediction, Felipe 25 Aug



        

Discussion:

The circle above is plotted at the expected 2320 km diameter of Eris. With only one chord it is not possible to determine whether Jonathan was north or south of the central line of the event so is plotted near the centre. This assumes that Bill may have had a near graze.

The figure below shows the Tangra light curve of Jonathan's occultation.

The figure below shows the Tangra light curve of Bill's occultation as analysed by Dave Heralds new tool AOTA in Beta test. This shows 4 possible locations that might be an occultation

This and the Tangra LC file have been examined with several fine tooth combs and it is still uncertain if the result is positive

The problem is that none of of possible events align with Jonathan's more definite result.

The figure above shows the most promising of the events located (the last one) but it simply does not fit. Unless Eris has a much stranger shape than expected for an object of this size.

{ a second event is possible as Eris is known to have a 250 km moon Dysnomia, however as we do not have good ephemeris for Dysnomia we cannot see if the 1 sample dip is consistent- jt}

Observational Data:

Observation details for MP ( 136199 ) Eris
By Star              1B
On 2013-08-29  at 15:28:42.0
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Observer   Jonathan Bradshaw
Location   Samford Valley,QLD,AU
Longitude  +152:50
Latitude   -27:22
Altitude   80 m
Datum      WGS84
Telescope SCT including Cass and Mak
Aperture   36 cm
Seeing     Steady Fog
Camera Type  WAT120N+       PAL/CCIR
Camera Delay -5.15
Timing     GPS - time inserted Video with frame analysis
Disappearance  15:37:43.25
Reappearance   15:38:44.73
Comments: Fog rolling in made a difficult event even more so! The occultation was clearly defined and a second extinction event lating 1 interval was noted some 23 seconds later and could not be acounted by seeing issues.

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Observer   William Hanna
Location   Alice Springs, Australia
Longitude  +133:53
Latitude   -23:42
Altitude   581 m
Datum      WGS84
Telescope SCT including Cass and Mak
Aperture   35 cm
Seeing     Steady Thin cloud < 2
Camera Type  Grasshopper Express with ADVS
Camera Delay 0
Timing     GPS - time inserted Video with frame analysis

Missed

Comments: gamma 2.222, gain 29dB, no moon
although the target star is just visible, the results must fairly be described as "inconclusive"


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