Narrow Band Photometry and the Reddening of CYG A

  • Karl D. Rakos
  • Norbert Fiala
Part of the Astrophysics and Space Science Library book series (ASSL, volume 121)


The use of narrow band (FWHM 200 Å) filters in extragalactic research is not new. Our photometric system vz, bz, yz is very similar to the Stroemgren v, b, y passbands. It has many advantages in conection with a CCD camera compared to broad band UBV photometry. These narrow passbands are less affected by emission lines than other filters in use. As example the Syfert galaxy POX 4 (Kunth and Sargent 1983) has for the B filter a total emission line width of a factor four larger than in the v filter calculated for equal spectral width. The filters b and y are not affected by emission lines, except for the very faint He II 4686 Å line and the blend Ar IV and He I 4711 Å. The v bandpass is only affected by H delta.


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Copyright information

© Springer Science+Business Media Dordrecht 1986

Authors and Affiliations

  • Karl D. Rakos
    • 1
  • Norbert Fiala
    • 1
  1. 1.Institut für AstronomieWienAustria

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