Doublestar analysis of lunar occultation of SAO146617 in Dec.6 2008

Observed by Hiroyuki Tomioka

Calculated by Kazuhisa Miyashita


Observation

Tomioka's report:

Place name  Hitachi, Ibaraki, Japan
20080518103122.71 S158556 DD     EG G0.04 1   W      21  13AA
20080518103127.80 X128805 DD     EG G0.04 3   E      21  13AA
A faint star, which has 10 magnitude brightness, is visible. It might be a component of the star of previous event.


Catalogue details

XZ double star file
XZ 31441 = SAO 146617 RA = 23 17 37.6247 PM = 0.01720s
Dec = - 1 31 17.958 PM = -0.0890"
Mv = 7.86, Mb = 0.00, Mr = 0.00 Spectrum G5 Approx dia. .0000"

Star is component A in the following system
Name Cmpt Yr1 Yr2:PA1 PA2 :Sep1 Sep2 :Mag1Mag2
BU 79AB 18761999:115.0 16.0:1.000 1.600: 8.259.73
BU 79AC 18941900:157.0161.0:16.00016.200:8.2016.70

WDS Discoverer codes
BU Burnham, S.W.

Orbital elements
Name Cmpt Period a" i node T e peri
BU 79 AB 388.35000 1.990000 108.1000 8.8000 2045.00000 0.49000 75.8000

Washington Double Star Catalog (WDS)
WDS Discovr Comp EPOCH # THETA RHO Magnitudes Spectra
Identifier Frst Last Fst Lst First Last Pri Sec Type
23176-0131BU 79AB 1872 2006 133 120 14 1.0 1.7 8.23 9.59 G5


Prediction

by OCCULT Ver.4
day Time P Star Sp Mag Mag % Elon Sun Moon CA PA VA AA Libration A B RV Cct
y m d h m s No D v r V ill Alt Alt Az o o o o L B m/o m/o "/sec o
08 Dec 6 7 47 34 D 146617SG5 7.9 54+ 94 -5 49 154 37N 14 34 36 -7.8 -3.5 +0.6+2.6 .306 36

146617 is triple: AB 8.3 9.7 1.4" 11.9 : AC 8.2 16.7 19.8" 233.6

Calculation

Position angle around Lunar limb is same as component's position angle of this double star. In this case, the separation of components is simply given as:
Sp = RV * dT
where Sp is separation of components; RV is Radial Velocity - the radial rate of motion of the star relative to the lunar limb, in arcsecs per second.; dT is the difference of event time of two components.
Time difference 5.51 second obtained from observation. Hence the separation is:
Sp=0.306 * 5.51 = 1.69
It is close to value descripted on WDS catalogue.

Conclusion

The separation of component of double star BU 79 (SAO146617) is confirmed by occultation observation. A result of occultation analysis agrees with WDS catalogue value.