Doublestar analysis of lunar occultation of SAO109032 in Dec.7 2008

Observed by Masayuki Ishida

Analized by Kazuhisa Miyashita

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Catalogue details XZ 124 = SAO 109032 RA = 0 8 48.4493 PM = 0.00174s Dec = 5 5 49.584 PM = 0.0096" Mv = 8.02, Mb = 8.96, Mr = 7.53 Spectrum G5 Approx dia. .0004" Star is the primary of the following pair Name Cmpt Yr1 Yr2: PA1 PA2 : Sep1 Sep2 : Mag1 Mag2 OCC 902 1994 1994: 57.0 : 0.050 : 9.00 9.00 OCC 902 observed by J Bourgeois on 1994 Jan 17 WDS Discoverer codes OCC Occultation discovery

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Observation site

Place name	Konohama-cho, Moriyama, Shiga, Japan
Longitude	135d 56m 33.6s East
Latitude	35d 06m 22.3s North
Horizontal Datum	WGS84
Altitude	85m

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Analysis

Fig.1    Analyzing by Limovie
The rectangle background region was used to subtract background value on the earth shined lunar limb. (Meteor/Lunar limb mode, width=7, gap=0)

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Diffraction fitting and photometry

Fig.2    Fitting to simulation curve which is considered moon distance and velocity


Fig.3    Fitting to double star simulation



There is vague outline of step in the light curve. However the change of luminous intensity is slower than expected from the contact angle and velocity of moon (Fig.2). It is thought that this not-instantaneous light change is generated by contact double star occultation, because this video has rather high S/N. From fitting analysis, the height of step is 31.3% of full brightness. Therefore, if assuming 8.02 as a visual (combined) magnitude of SAO109032, the main component of SAO109032 is 8.43 mag. And the fainter component is 9.28 mag.

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Timing

Time of field(No.126.5) centre is 10h15m23.83s. The fitting result indicates first event occurred 0.021 second before the field centre, and the time difference between two events is 0.025 second. From this, the first event is at 10h15m23.81s and second event is 10h15m23.84s

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Result

Object	Phenomenon	Time	magnitude
Component B	Disappearance	10h15m23.81s +/- 0.017sec	8.43
Component A	Disappearance	10h15m23.84s +/- 0.017sec	9.28
Time difference		0.025 sec
Separation assuming PA is equal to event's PA		0.009 arcsec

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