Astronomy 162
Introduction to Stellar, Galactic & Extragalactic Astronomy

Digital Movie Notes

Index


Parallax

The parallax movie was created from 156 GIF images generated on a Sun SPARCstation 10/40 using the custom Fortran program parallax.f, which calls the PGPlot graphics subroutine library. The GIFs were converted into PICT format using the ImageMagick convert program, and combined into a QuickTime movie on a Mac Performa using MooVer v1.3. The movie was composed at 12 frames/second with video compression.

The GIF movie was composed by regenerating the GIFs at a reduced size and combining using the ImageMagick convert utility.

The MPEG movie was directly encoded from reduced-sized (320x320) GIFs using the mpeg_encode program. For some reason the full-size GIFs encoded funny. MPEG is weird.

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Proper Motion

The position and proper motion data for the Ursa Major star field are from the SAO Catalog. The movie was created from 201 GIFs generated on a Sun SPARCstation 10/40 using the custom Fortran program pmgiffer.f, which calls the PGPlot graphics subroutine library.

The GIFs were converted into PICT format using the ImageMagick convert program, and then combined into a QuickTime movie on a Mac Performa using MooVer v1.3. The movie was composed at 24 frames/second with video compression.

The GIF movie was composed by regenerating the GIFs at a reduced size and combining using the ImageMagick convert utility.

The MPEG movie was directly encoded from reduced-sized (480x360) GIFs using the mpeg_encode program.

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Visual Binary Stars

These two movies are each composed of 96 GIFs generated on a Sun SPARCstation 10 using the custom Fortran program binary.f, which calls the PGPlot graphics subroutine library. For each, the program used parameters appropriate for a F0v primary and M0v secondary star. A first-order limb-darkening law (u1=0.59) was used to render the stars using a 64-level intensity map at the given color for each star. The color was estimated using the effective temperature of the star and using a routine to convert a blackbody spectrum to approximate RGB color.

A 3-rd order Keplerian orbit calculator was used, with user input for the eccentricity, inclination with respect to the line of sight, and the apsidal angle (angle of the long-axis of the orbits with respect to the plane of the sky). A green dot is used to mark the location of the center-of-mass of the system.

The first movie is of a circular orbit (e=0) seen with the plane of the orbit in the plane of the sky.

The second movie is of an elliptical orbit (e=0.4) also with the orbital plane in the sky plane, but with the angle of apsides rotated 45°.

The GIFs were converted into uncompressed PICT files using the GraphicConverter program on a Mac Performa, and then combined into a QuickTime movie using MooVer v1.3. Each movie was composed at 12 frames/second with video compression.

The MPEG movies were directly encoded from the GIFs using the mpeg_encode program (using on-the-fly conversion to PPM with giftoppm). The encoding is still jumpier than I'd like, and I hope to refine them over time.

The GIF movies were composed by regenerating the GIFs at a reduced size and combining using the ImageMagick convert utility. The quality of the stellar photosphere rendering is noticeably superior to that in the QT movies.

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Spectroscopic Binary Star

This movie is composed of 64 GIFs generated on a Sun SPARCstation 10 using the custom Fortran program spbin.f, which calls the PGPlot graphics subroutine library. The program assumed a simple circular orbit, and used parameters appropriate for an F0v primary and M0v secondary star. The calculation used an orbital inclination of 0° with respect to the observer's line of sight. A first-order limb-darkening law (u1=0.59) was used to render the stars using a 32-level intensity map at the given color for each star. The color was estimated from the effective temperature of the star and using a routine to convert a blackbody spectrum to approximate RGB color.

The spectral line shifts were computed using the projected velocity along the plot's X-axis. The relative Doppler shift is greatly exaggerated to aid visibility. The color bar in the background of the spectrum was generated from 65 RGB points across a standard "rainbow" color lookup table.

The GIFs were converted into uncompressed PICT files using the GraphicConverter program on a Mac Performa, and then combined into a QuickTime movie using MooVer v1.3. The movie was composed at 12 frames/second with video compression.

The MPEG movie was directly encoded from the GIFs using the mpeg_encode program (using on-the-fly conversion to PPM with giftoppm). The encoding is still jumpier than I'd like, suggestions are welcome.

The GIF movie was composed by regenerating the GIFs at a reduced size and combining using the ImageMagick convert utility. The quality of the stellar photosphere rendering is noticeably superior to that in the QT movie.

Go to: [Movie Page| Details Index]


Eclipsing Binary Star

This movie is composed of 96 GIFs generated on a Sun SPARCstation 10 using the custom Fortran program eclipse.f, which calls the PGPlot graphics subroutine library. The program assumed a simple circular orbit, and used parameters appropriate for an A0v primary and G2v secondary star. The calculation used an orbital inclination of 6° with respect to the observer's line of sight. A first-order limb-darkening law (u1=0.59) was used to render the stars using a 64-level intensity map at the given color for each star. The color was estimated from the effective temperature of the star and using a routine to convert a blackbody spectrum to approximate RGB color.

Some of the smoothness of this rendering is lost in the video compression for the QuickTime movie, but appears in the animated GIF. The light-curve was computed directly assuming uniform surface-brightness stellar disks (no limb darkening) for simplicity.

The GIFs were converted into uncompressed PICT files using the GraphicConverter program on a Mac Performa, and then combined into a QuickTime movie using MooVer v1.3. The movie was composed at 12 frames/second with video compression.

The MPEG movie was directly encoded from the GIFs using the mpeg_encode program (using on-the-fly conversion to PPM with giftoppm). The encoding is still jumpier than I'd like, suggestions are welcome.

The GIF movie was composed by regenerating the GIFs at a reduced size and combining using the ImageMagick convert utility. The quality of the stellar photosphere rendering is noticeably superior to that in the QT movie.

Go to: [Movie Page| Details Index]


Prof. Richard Pogge (pogge@astronomy.ohio-state.edu)

Updated: 2016 May 14 [rwp]

Copyright Richard W. Pogge, All Rights Reserved.