A Three chords were recorded , using Video OSD technique.
One clearly observed miss was recorded for this event.
View the updated prediction.
Observers: 1(M) G Hudson,Porirua, New Zealand 2 M Forbes,Lower Hutt 3 M Unwin,Wanaka, New Zealand 4 A Pennell, Dunedin, New Zealand 5(P) Prediction, 01 April
The ellipse above is plotted at the best fit axis ratio as determined by Occult. With 3 chords we can be confident of the path of Aspasia and that it was north of the predicted line. The Damit/ISAM 3D model has been overlaid on the measured ellipse and shows poor fit. This has turned out to be quite a difficult event to sort out and even now the result is only partially satisfactory. The main problem is that the star was faint (mag 12.7) and the mag drop was small (0.2 m) All observers were using long integration times (x32 to x64 frames = 1.28 to 2.56 secs) so the time resolution is poor even when measured using AOTA and R-OTE. I have checked and rechecked Gordon's data and cannot find anything that is a convincing dip. The other 3 observers have dips that are consistent with the expected mag drop but all seem to show slow D and R. It seems that the major source of noise is in the Analogue cables and the A to D converter. All observers are to be congratulated in end up with data that is of sufficient accuracy to get a reasonable match with the DAMIT model.
The figure below shows the Tangra light curve of Martin's occultation as analysed by AOTA for the main event.
Observation details for MP ( 409 ) Aspasia By Star UCAC4 492-144257 On 2014-08-30 at 14:50:37.0 _______________________________ Observer Murray Forbes Location Lower Hutt Longitude +174:58 Latitude -41:09 Altitude 25 m Datum WGS84 Telescope SCT including Cass and Mak Aperture 20 cm Seeing Slight flickering Clear Camera Type WAT120N+ PAL/CCIR Camera Delay -0.19 Timing GPS - time inserted Video with frame analysis Disappearance 14:50:35.89 Reappearance 14:50:42.53 Comments: Lightcurve generated by Limovie. Occult's AOTA used to analyse event, giving the large uncertainties in the times. Report prepopulated by IOTA Reporting Add-in for OW ver.1.8 _______________________________ Observer G Hudson Location Porirua, New Zealand Longitude +174:50 Latitude -41:06 Altitude 52 m Datum WGS84 Telescope SCT including Cass and Mak Aperture 30 cm Seeing Steady Clear Camera Type WAT120N+ PAL/CCIR Camera Delay -0.05 Timing GPS - time inserted Video with frame analysis Missed Comments: Video scan by Limovie Time analysis by AOTA _______________________________ Observer Martin Unwin Location Wanaka, New Zealand Longitude +169:06 Latitude -44:41 Altitude 300 m Datum WGS84 Telescope Newtonian Aperture 15 cm Seeing Steady Clear Camera Type WAT120N PAL/CCIR Camera Delay -0.67 Timing GPS - time inserted Video with frame analysis Disappearance 14:51:26.06 Reappearance 14:51:41.74 Comments: Video scanned with Limovie and times extracted using AOTA. Line of sight just above roof of house, seeing affected by thermals. Report prepopulated by IOTA Reporting Add-in for OW ver.1.8 _______________________________ Observer Ash Pennell Location Dunedin NZ Longitude +170:29 Latitude -45:52 Altitude 136 m Datum WGS84 Telescope SCT including Cass and Mak Aperture 35 cm Seeing Slight flickering Clear Camera Type WAT120N+ PAL/CCIR Camera Delay -1.31 Timing GPS - time inserted Video with frame analysis Disappearance 14:51:26.30 Reappearance 14:51:36.82 Comments: Times by Aota Tangra scan