Intermidiate step of luminous intensity was found from video photometry of SAO93062 (XZ3617) occultation

Kazuhisa Miyashita

Nov.25 2007


1. Introduction

SAO93062 occultation in Nov.23 2007 was recorded to Digital Video tape and photometric analyzed using Limovie. The light curve shows a small step in decreasing light change of disappearance. The step consists of two frames which have almost same intensity in each other. It is considered the step is formed by double star occultation with higher possibility because the noise of air scintillation is rather small and it is not large enough to make such a step.

The result of this analysis is :

Separation of two components in direction of position angle of event of lunar limb (93 degree) is 0.018 arcsec.

Magnitude of component A is 6.09 mag. and component B is 6.96 mag.


Figure 1. SAO occultation in Nov.23 2007

Analyzing was used Linked tracking feature to remove the influence of lunar limb briten by earth shine.


2. Desciption of SAO93062 about double star

The feature of SAO93062 as a double star is described in WDC and XZ double star file. It should be refferenced in this analysis and discussion. However there are curious desciption in magnitude. The value of 2.38 (in Mu Ari B) is considered wrong value. And if the magnitude of components are 5.69 and 6.2 then the total magnitude should be 5.1 mag. Probably there are tipe miss of this catalog.

Table 1. Feature of SAO described in Washington Double Star Catalog

Name

Observation

Position angle

Separation

Magnitude

Spectrum type



First

Last

First

Last

First

Last

Component A

B

BLA 1Aa

1975

1999

147

281

0.0

0.0

5.69

6.2

A0V


Table 2. Feature of SAO described in XZ Double Star Catalog

No.

Name

Observation

Position angle

Separation

Magnitude

Spectrum type

First

Last

First

Last

First

Last

Component A

B

3617

Mu Ari B

1969

1973

189

276

0.004

0.047


2.38

A0V

3617

BLA 1Aa

1975

1988

147

281

0.0

0.0

5.69

6.2

A0V

3617

BU 522 Aa-B

1878

1934

266

265

19.1

19.2

5.7

12.2

AOV


3. Analysys and diffraction fitting


The lunar's distance (D) 353354km is obtained from LOW(Lunar Occultatin Workbench) Ver4. The shadow velocity (Vs) is 891m/s calculated from formula:

Vs=RV*D/cos(cct) .

The function of diffraction simulation is not considered the frame exposure. The fitting is done to compare with point value of simulation curve. Therefore there is errors in this fitting. However the error is considered small (probably in 10 milli second).

A result of diffraction simulation and fitting is shown in Figure 2. The separation (Se) of both components is 18 arcsec calculated from formula:

Se=Dt*RV (Dt is lunar's distance (m); RV is relative velocity which is velocity to the direction to perpendicular to lunar limb.)

If the magnitude of pair is 5.69 then the magnitude of component A is 6.09 and component B is 6.96.


Figure 2. Luminous change obtained from Limovie analysis