. The Astrophysical journal. with (i) we see that the measured velocity needsthe correction K cos (I sm ) . (3) 2 \ U2—U1 2 J 10b MIXOK COyfRIBLTRlWS A\D M)TES The numerical values for this ciK^fficient of A are gi\-en in Table vertical argument is the mean phase, and the horizontal argu-ment is the length of exposure expressed in fractions of the periodof oscillation, and also in degrees of arc. TABLK I Values of Cos ih+tti 1ti—Ui= o o°... lO I 20 30 1 40 ; 50 60 70 80 90 100 no 120 i 130 140 150 1 160 170 180 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
. The Astrophysical journal. with (i) we see that the measured velocity needsthe correction K cos (I sm ) . (3) 2 \ U2—U1 2 J 10b MIXOK COyfRIBLTRlWS A\D M)TES The numerical values for this ciK^fficient of A are gi\-en in Table vertical argument is the mean phase, and the horizontal argu-ment is the length of exposure expressed in fractions of the periodof oscillation, and also in degrees of arc. TABLK I Values of Cos ih+tti 1ti—Ui= o o°... lO I 20 30 1 40 ; 50 60 70 80 90 100 no 120 i 130 140 150 1 160 170 180 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 . 36 .00+0. + . +++ 00 + 00!+ 000000000000000000000000 + .01 +0 + . + . + . + . + . + . + . + . . .01 I .02|- .02 — .02;—O +0, + . + . + . + . + . + ..01+ ..01 + . . —.01 —. 02 —. 02 — • 03 -? 03 - • 03 . ? ?OS . 04— + 0 + + + + + + + + 108° + 0 + + + + + + 031 + 02j +00!02 —03J- 05 - 06 -08-091-09 — 10. We see from (3) that if the spectrograms have all been exposedfor the same length of time the correction is proportionate to thetrue velocity at the corresponding mean phase; consequentlythe effect of the error that we are discussing would be to diminishthe semi-amplitude of oscillation without changing in any otherway the shape of the velocity-curve. While this is strictly trueonly if the lengths of exposures are the same, it will be approxi-mately true in any case that will arise in practice, so long as theaverage length of exposure is about the same for various parts ofthe velocity-cur\e. MINOR CONTRIBUTIONS AND NOTES 169 A convenient procedure for applying this correction is as follows:The observations are plotted in the usual way and from this isderived a tirst approximation, K, to the semi-amplitude. This vdWbe too small by an amount that we may ascertain from the firstline in the table. Thus, if the average length of exposure is four-tenths of the period,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectspectru, bookyear1895
