Augmenting Light Curve Based Attitude Estimation with Geometric Information

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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RSCVn Stars in the Southern Hemisphere

International Astronomical Union Colloquium ◽

10.1017/s0252921100073644 ◽

1979 ◽

Vol 46 ◽

pp. 371-384 ◽

Cited By ~ 3

Author(s):

J.B. Hearnshaw

Keyword(s):

Light Curve ◽

Southern Hemisphere ◽

Orbital Period ◽

Binary Stars ◽

Small Amplitude ◽

Light Variation ◽

Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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On the Shape of Field-Ion Emitters

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092566 ◽

1976 ◽

Vol 34 ◽

pp. 520-521

Author(s):

H.C. Eaton ◽

B.N. Ranganathan ◽

T.W. Burwinkle ◽

R. J. Bayuzick ◽

J.J. Hren

Keyword(s):

Grain Boundary ◽

Spherical Shape ◽

Theoretical Strength ◽

Evaporation Process ◽

Field Evaporation ◽

Geometric Information ◽

Field Ion Microscopy ◽

Considerable Error ◽

True Shape ◽

Ion Microscopy

The shape of the emitter is of cardinal importance to field-ion microscopy. First, the field evaporation process itself is closely related to the initial tip shape. Secondly, the imaging stress, which is near the theoretical strength of the material and intrinsic to the imaging process, cannot be characterized without knowledge of the emitter shape. Finally, the problem of obtaining quantitative geometric information from the micrograph cannot be solved without knowing the shape. Previously published grain-boundary topographies were obtained employing an assumption of a spherical shape (1). The present investigation shows that the true shape deviates as much as 100 Å from sphericity and boundary reconstructions contain considerable error as a result.Our present procedures for obtaining tip shape may be summarized as follows. An empirical projection, D=f(θ), is obtained by digitizing the positions of poles on a field-ion micrograph.

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