A new component found from SAO164647 occultation in Apr.30 2008

May.3 2008

Reviced May.4 2008

Kazuhisa Miyashita

1. Introduction

Masayuki Ishida videotaped an event that the SAO164647 occulted by the moon. He found a step in the light curve and he kindly sent me the video as an .avi file. I analyzed the file using Limovie software and measured the step duration and step height. There isn't any description about this star in WDC and XZ double star file. So, it is considered that it is a discovery of a new double star.

2. Prediction

Predicted by OCCULT4 is below.


Occultation prediction for Ishida, Konohama

E. Longitude 135 56 33.6, Latitude 35 6 22.3, Alt. 86m;


day Time P Star Sp Mag Mag % Elon Sun Moon CA PA VA AA Libration

y m d h m s No D v r V ill Alt Alt Az o o o o L B

08 Apr 29 19 11 44 R 164647 F3 7.7 7.4 37- 76 -11 25 131 22S 182 222 200 -7.3 +0.8


A B RV Cct R.A. (J2000) Dec

m/o m/o "/sec o h m s o m s

+0.8+3.5 .201 -120 21 47 10.3 -14 30 50


Librations Long -7.22 Lat +0.83

P +171.15 D -0.02

Illumination of moon 38%-

Elongation of Moon 76

Vertical Profile Scale 3.50 km/arcsec at mean distance of moon

Horizontal Scale Factor 1.50 deg/min


Figure 1 Moon map (Based on the moon map derived from OCCULT4)

3. Observation

Ishida reported this observation to ILOC as follows.


TACED 30.0 300.0 135 56 33.6 E 35 06 22.3 N 85.0JGD2000 TODAU


1308042919114731 S 164647TODAU 2V CE 0041 AAA


4. Analyzing

The light curve obtained from SAO164647 event and a result of diffraction fitting is below.

Figure 2 Light curve and a result of diffraction fitting

The result of timing is below.

Appearance of second star : 19h11m47.21s +/-0.01sec (UTC)

Appearance of main star : 19h11m47.60s +/-0.01sec (UTC)

The duration when only the fainter star appeared is 0.387 second. The step height is 39.8% of full brightness. If the pair is 7.7 mag then the magnitude of each components are below.

Main component : 8.25 mag.

Second component : 8.75 mag.

If it is assumed the position angle of the companion star is equal to the event's position angle, then the separation is 0.08 arcsec.

Figure 3 Astrometry of components

When assuming that the component's position angle is equal to event's position angle.


It is not found any description about double star from the Washington Double star Catalogue and XZ double star catalogue. So, it is considered that SAO164647 is a _new double star_.