Annals of the Astronomical Observatory of Harvard College Volume 71 download
Annals of the Astronomical Observatory of Harvard College Volume 71 download
Annals of the Astronomical Observatory of Harvard College Volume 71.cHarvard College Observatory
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Author: Harvard College Observatory
Page Count: 60 pages
Published Date: 01 May 2012
Publisher: Rarebooksclub.com
Publication Country: Miami Fl, United States
Language: English
ISBN: 9781236102072
File Name: Annals.of.the.Astronomical.Observatory.of.Harvard.College.Volume.71.pdf
Download Link: Annals of the Astronomical Observatory of Harvard College Volume 71
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...Telescope, that the images closely resemble those taken with the full aperture, while images taken with the small aperture over the centre have sharper definition. In taking photographs with large and small apertures, the diaphragm was nearly always placed in position c, midway between the centre and edge of the objective. If it was placed over the centre, in the case of plates taken with the 11-inch Draper Telescope, 0.1 magn. was subtracted from the computed value of the difference, when reducing the observations. The effect of diffraction is probably negligible for the apertures used with this telescope. If we assume that the effective aperture is in each case reduced 0.1 cm. by diffraction, the computed difference is increased only 0.01 magn. Prismatic Companions. The small auxiliary prism placed over the objective of the 8-inch Draper Doublet, and deflecting about a hundredth part of the light, which forms "prismatic companions" to the brighter images, is one of the most valuable of the methods tried for obtaining absolute magnitudes. The fact that only one exposure is required is a great advantage, as errors arising from changes in the atmosphere, temperature, photographic film, etc., are avoided. Other advantages are the saving of the time of the instrument, and the fact that every chart plate furnishes the means of determining magnitudes on an absolute scale. A disadvantage is that the images are smaller and more sharply defined than the principal images, on account of the small size of the aperture, 20 mm. Near the centre of the plate the dissimilarity can hardly be detected, if the images are circular, but as the distance is increased, the images become so unlike that the method cannot then be used. The same is true if the focus is poor ...
Read online Annals of the Astronomical Observatory of Harvard College Volume 71 Buy Annals of the Astronomical Observatory of Harvard College Volume 71 Download and read Annals of the Astronomical Observatory of Harvard College Volume 71 ebook, pdf, djvu, epub, mobi, fb2, zip, rar, torrent Download to iPad/iPhone/iOS, B&N nook Annals of the Astronomical Observatory of Harvard College Volume 71 ebook, pdf, djvu, epub, mobi, fb2, zip, rar, torrent
Annals of the Astronomical Observatory of Harvard College Volume 71.cHarvard College Observatory
Author: Harvard College Observatory
Page Count: 60 pages
Published Date: 01 May 2012
Publisher: Rarebooksclub.com
Publication Country: Miami Fl, United States
Language: English
ISBN: 9781236102072
File Name: Annals.of.the.Astronomical.Observatory.of.Harvard.College.Volume.71.pdf
Download Link: Annals of the Astronomical Observatory of Harvard College Volume 71
---------------------------------------------------------------
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...Telescope, that the images closely resemble those taken with the full aperture, while images taken with the small aperture over the centre have sharper definition. In taking photographs with large and small apertures, the diaphragm was nearly always placed in position c, midway between the centre and edge of the objective. If it was placed over the centre, in the case of plates taken with the 11-inch Draper Telescope, 0.1 magn. was subtracted from the computed value of the difference, when reducing the observations. The effect of diffraction is probably negligible for the apertures used with this telescope. If we assume that the effective aperture is in each case reduced 0.1 cm. by diffraction, the computed difference is increased only 0.01 magn. Prismatic Companions. The small auxiliary prism placed over the objective of the 8-inch Draper Doublet, and deflecting about a hundredth part of the light, which forms "prismatic companions" to the brighter images, is one of the most valuable of the methods tried for obtaining absolute magnitudes. The fact that only one exposure is required is a great advantage, as errors arising from changes in the atmosphere, temperature, photographic film, etc., are avoided. Other advantages are the saving of the time of the instrument, and the fact that every chart plate furnishes the means of determining magnitudes on an absolute scale. A disadvantage is that the images are smaller and more sharply defined than the principal images, on account of the small size of the aperture, 20 mm. Near the centre of the plate the dissimilarity can hardly be detected, if the images are circular, but as the distance is increased, the images become so unlike that the method cannot then be used. The same is true if the focus is poor ...
Read online Annals of the Astronomical Observatory of Harvard College Volume 71 Buy Annals of the Astronomical Observatory of Harvard College Volume 71 Download and read Annals of the Astronomical Observatory of Harvard College Volume 71 ebook, pdf, djvu, epub, mobi, fb2, zip, rar, torrent Download to iPad/iPhone/iOS, B&N nook Annals of the Astronomical Observatory of Harvard College Volume 71 ebook, pdf, djvu, epub, mobi, fb2, zip, rar, torrent