comparison star

comparison star

[kəm′par·ə·sən ‚stär]
(astronomy)
A star of known brightness used as a standard for comparison in determining the magnitude of a nearby celestial object.
References in periodicals archive ?
Essentially, one records the brightness of a comparison star of known brightness and then measures the brightness of the target.
The Magnitude scale was derived from a virtual comparison star and is only an approximation for V mag.
The brightness of each was compared with that of two supposedly constant stars, the comparison star and the check star that were close on the sky to the variable star.
Due to a problem with the comparison star the data were not analyzed.
The comparison star used for all measurements was 62 [xi] -Cyg while 61-Cyg A and v-Cyg were check stars for some of the measurements.
This field should ensure that almost all of the light from Saturn and the comparison star reach the detector.
The values obtained from these sources are consistent to within 0.02 magnitudes when using a calibration method involving the Canopus add-on, Comparison Star Selector, which picks comparison stars of similar colour and magnitude to the target star.
The sixth column of Table I lists the comparison star used for each measurement.
Each 60s exposure image was dark-field subtracted using the relevant nightly dark-field image, and the magnitude of CQ Cep determined by differential photometry using AstroArt 5.0 and a 10.08 V magnitude comparison star (TYC 3991-1480-1) together with a 10.62 V mag check star (TYC 3991-2054-1).
Mu-Leonis was the comparison star and Epsilon-Leonis was the check star for all magnitude measurements.
The comparison star for all measurements was iota Geminorum; the magnitudes were taken from Iriarte et al.
This is a different method of estimation in which you try to judge the brightness difference between the variable and just one comparison star in steps of tenths of a magnitude.