Observation and analysis of SAO76169 on Jan. 25, 2010 (UTC)

Mar. 14, 2010
Kazuhisa Miyashita

The detail of SAO76169 is as follows.

Catalogue details

XZ 4871 = SAO 76169
RA =   3 46 15.9987   PM = 0.00131s
Dec =  24 11 23.743    PM = -0.0410"
Mv = 8.10, Mb = 8.40, Mr = 7.94    Spectrum A3    Approx dia. .0001"

Star is component A in the following system
Name    Cmpt   Yr1  Yr2: PA1   PA2  :   Sep1   Sep2  :  Mag1  Mag2:     #1      #2  mean
BU  536 AB    1878 2008: 336.0 180.0:   0.400   1.000:  8.13  9.39: S 76169 X 67221
S   437 AB-C  1823 2007: 300.0 308.0:  34.600  39.300:  8.13  7.70: S 76169 S 76167
BU  536 CD    1878 2003:  11.0   6.0:  18.200  16.500:  7.70 11.70: S 76167  ------

WDS Discoverer codes
BU   Burnham, S.W.
S    South, J.

Orbital elements
Name  Cmpt     Period       a"        i       node      T        e       peri
BU  536 AB     885.64000  1.211000  99.3000 175.3000 1877.90000 0.31400 245.5000
Year   PA    Sep
2008 179.92  0.97
2009 179.82  0.98
2010 179.72  0.98
2011 179.63  0.99
2012 179.54  0.99

The occultation event of this star was observed by three Japanese observers on Jan. 25, 2010. This star was also observed by S. Messner in USA on Aug. 14, 2009.
Separation and position angle between component A and B is obtained from these observations. And the magnitude difference is also estimated.

Double star solution by IOTA coordinator

Comment from Brian Loader (double star coordinator).

>2010 Jan 25 at 11h 4m Star = S76169 Observer = H. Watanabe
>
>BU 536 AB 1878 2008: 336.0 180.0: 0.400 1.000: 8.13 9.39: S
>76169 X 67221
>
> T2-T1 = -5.10
> * * * * *

Thank you for this observation by Watanabe-san. I have made a new solution for this double. It is attached.

As you will see, the errors have in fact increased. This is not surprising as the limb PAs of the three Japanese observers are all close.
Taken on their own, without S. Messner's observation the solution has large errors:

PA 250.99+/-8.67 degrees, separation 1.579 +/- 0.318"

We really need yet another observation at a different PA on the Moon's limb!

Best wishes,
Brian

Photometry

K. Kenmotsu H. Watanabe mean Brighter star: 8.41 +/- 0.02 8.37 +/- 0.04 8.39 +/- 0.03 Fainter star: 9.61 +/- 0.06 9.75 +/- 0.11 9.68 +/- 0.07

The magnitude difference derived from observation is very close to the value of WDS catalogue.

Light curve and explanation

i) Kenmotsu's observation

ii) Ishida's observation

The video of this observation had been analyzed with a process which is like to the LimovieAverage using spread sheet program for the purpose of correcting the influence of bright thin clouds. As a result, a step which is similar to Kenmotsu-san's observation had been obtained.