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Astronomical Photometry

Astronomical Photometry. How to get from there to here. Stars , sky , observing , telescope, filters , detector, noise, reduction, graphing. Apparent magnitude of a star will depend on: Luminosity Distance ( F is flux) Stuff in between it and us (extinction; reddening). Stars.

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Astronomical Photometry

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  1. Astronomical Photometry How to get from there to here Stars, sky, observing, telescope, filters, detector, noise, reduction, graphing

  2. Apparent magnitude of a star will depend on: Luminosity Distance (F is flux) Stuff in between it and us (extinction; reddening) Stars Definition of magnitude (visual wavelengths): Definition of “color” of a star:

  3. Getting the effective temperature of a star using UBVRI FILTERS Color of star will also depend slightly on chemical composition (metal-rich vs metal-poor)

  4. Filters B V R B V R

  5. We always use filters. Original filter set was for a photometer, not CCDs. Telescopes may have different sets of filters (width and peak of band passes may differ, response may differ); may need to TRANSFORM magnitudes to a standard system.

  6. Reddening (“de-bluing”) Antares/Rho Ophiuchus Region

  7. Color Excess Slope of the reddening line for stars earlier than A0: Find star here Extrapolate there For cooler stars, must use spectroscopy.

  8. Sky Bad, badder, baddest!

  9. Z

  10. Observations CV’s

  11. FIG. 1.Light curves are presented for the six variable stars. Points represent observed data in B (filled circles), V (asterisks), and I (open circles). The dotted curves represent the best-fitting template to the observed data. The vertical axis in each panel spans 2 mag.

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