Three positive occultations were recorded using video OSD technique.

Two clearly observed misses were recorded for this event.

View the updated prediction.

Observers:
  1(M) J Bradshaw,Samford Valley, Qld, AU
  2(M) J Broughton,Reedy Creek, QLD, AU
  3    J Broughton,Ballina, NSW, AU
  4    C Chad,Vickery, NSW,AU
  5    C Chad,Gunnedah, NSW,AU
  6(P) Prediction 7 August


        

Discussion:

The ellipse above is plotted at the best fit axis ratio of 1.05 as determined by Occult. This is slightly smaller than the maximum axis ratio as determined by lightcurve inversion data of 1.09 With 3 chords we can be confident of the path of Isolda and that it was slightly south of the predicted line.

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

The figure below shows Chris's Tangra light curve of the occultation form his mobile station.

The figure below shows Chris's Tangra light curve of the occultation from his home station.

This curve show very slow D and R which Chris has established was caused by his Samsung SCB-2000 video camera which does integration in a similar way to WATEC but is also using SSNR3 or Samsung Super Noise Reduction3 which appears to be a sliding average algorithm to reduce "noise" (read sudden changes). Chris says "Clearly the lesson is to make sure the noise reduction is turned off." There appears to be a slow D in all the above data and WDS says that the star is interferometric multiple with at least 4 components ranging in manitude from 9.36 to 15.53.

Observational Data:

Observation details for MP ( 211 ) Isolda
By Star              TYC 1880-01245-1
On 2012-09-27  at 17:16:17.0

_______________________________

Observer   John Broughton
Location   Reedy Creek, QLD, AU
Longitude  +153:23
Latitude   -28:06
Altitude   66 m
Datum      WGS84
Telescope SCT including Cass and Mak
Aperture   25 cm
Seeing     Slight flickering Clear
Camera Type  WAT120N        PAL/CCIR
Camera Delay 0.17
Timing     GPS - time inserted Video with frame analysis

Missed

Comments:

_______________________________

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 Clear
Camera Type  G-Star         PAL/CCIR
Camera Delay 0.03
Timing     GPS - time inserted Video with frame analysis

Missed

Comments:   Report prepopulated by IOTA Reporting Add-in for OW ver.1.6

_______________________________

Observer   John Broughton
Location   Ballina, NSW, AU
Longitude  +153:32
Latitude   -28:50
Altitude   11 m
Datum      WGS84
Telescope Newtonian
Aperture   32 cm
Seeing     Slight flickering Clear
Camera Type  WAT120N        PAL/CCIR
Camera Delay 0.05
Timing     GPS - other linking Video with frame analysis
Disappearance  17:16:15.74
Reappearance   17:16:21.02
Comments: The integration was doubled to 4x in Tangra to reduce noise.
A duration of 5.28 at the 50% level was measured from the plot.
The absolute time of R was measured in VirtualDub,
requiring a 3.77s subtraction for DVR time-stamp offset and 0.05 for 2x integration.
The 5.28s duration was subtracted from R to establish an absolute time
for the apparently less-abrupt position of D.

_______________________________

Observer   Chris Chad
Location   Gunnedah, NSW
Longitude  +150:15
Latitude   -30:59
Altitude   315 m
Datum      WGS84
Telescope Newtonian
Aperture   25 cm
Seeing     Slight flickering Thin cloud < 2
Camera Type  Other integrating            NTSC/EIA
Camera Delay 0.15
Timing     GPS - time inserted Video with frame analysis
Disappearance  17:16:08.40
Reappearance   17:16:14.98
Comments: Samsung SCB-2000 (modded) -
34ms subtracted from times for frame delay
Star oserved to dim and brighten, rather than expected abrupt event.
High clouds a feature of the night.  Integration high to compensate.
Extra 0.267 ms taken of time to allow for camera noise smoothing.
_______________________________

Observer   Chris Chad
Location   Vickery, NSW
Longitude  +150:11
Latitude   -30:47
Altitude   307 m
Datum      WGS84
Telescope Newtonian
Aperture   15 cm
Seeing     Slight flickering Thin cloud < 2
Camera Type  Other integrating            NTSC/EIA
Camera Delay 0.25
Timing     Video + audio time signal Video with frame analysis
Disappearance  17:16:07.16
Reappearance   17:16:14.12
Comments: Samsung SCB-2000 (modded) times derived from audio in recording calibrated
to IOTA VTI (3hrs earlier)
Drift through video. High clouds a feature of the night.
Integration high to compensate.