An Etymological Dictionary of Astronomy and Astrophysics
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The difference between the → visual magnitude and → bolometric magnitude.

→ bolometric; → correction.

1) The act or process of correcting.
2) A quantity added to a calculated or observed value to obtain the true value.
3) Something that is substituted or proposed for what is wrong or inaccurate.

Noun form of → correct.

In → photometric calibration, the correction for energy loss undergone by radiation due to the → atmospheric extinction. Extinction correction is done using → standard stars observed at different → airmasses.

→ extinction; → correction.

A quantity used in studies of → emission nebulae to convert the → ionic abundance of a given chemical element to its total → elemental abundance. The elemental abundance of an element relative to hydrogen is given by the sum of abundances of all its ions. In practice, not all the ionization stages are observed. One must therefore correct for unobserved stages using ICFs. A common way to do this was to rely on → ionization potential considerations. However, → photoionization models show that such simple relations do not necessarily hold. Hence, ICFs based on grids of photoionization models are more reliable. Nevertheless here also care should be taken for several reasons: the atomic physics is not well known yet, the ionization structure of a nebula depends on the spectral energy distribution of the stellar radiation field, which differs from one model to another, and the density structure of real nebulae is more complicated than that of idealized models (see, e.g., Stasińska, 2002, astro-ph/0207500, and references therein).

→ ionization; → correction; → factor.

A → color index correction applied to the photometric magnitudes and colors of a distant galaxy to compensate for the "reddening" of the galaxy due to → cosmological redshift. K correction is intended to derive the magnitudes in the → rest frame of the galaxy. Typically it is given as K(z) = az + bz², where a and b depend on galaxy types. Conversely, one may deduce the redshift of a galaxy by its colors and a K-correction model.

The term K correction, probably stems from the K-term used by C. W. Wirtz (1918, Astron. Nachr. 206, 109), where K stands for Konstante, the German word for constant. The K-term was a constant offset in the redshift applied to diffuse nebulae in that epoch (source: A. L. Kinney, 1996, ApJ 467, 38); → correction.

A correction introduced into star counts distributed by apparent magnitude.

→ Malmquist bias; → correction.

A term inserted into a formula for the energy of a single electron in the outermost shell of an atom to take into account the failure of the inner electron shells to screen the nuclear charge completely.

→ rydberg; → correction.

In → adaptive optics, eliminating the effects of atmospheric turbulence on the wavefront of the object being observed. → wavefront distortion.

→ wavefront; → correction.