Star in the constellation Boötes
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! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Spectral type
! style="text-align:left" | U−B 
! style="text-align:left" | B−V 
! style="text-align:left" | R−I 
! style="text-align:left" | Variable type
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HD 123657, or BY Boötis, is a variable star of magnitude 4.98–5.33V. This makes it a dim naked eye star. The star is located near the end of the handle of the Big Dipper, but just within the boundaries of the constellation Boötes.
The variability of the brightness of HD 123657 was announced by Joel Stebbins and Charles Morse Huffer in 1928, based on observations made at Washburn Observatory. The star was given its variable star designation, BY Boötis, in 1973. It is a slow irregular red giant variable star with a range of less than half a magnitude. It is over a thousand times as luminous as the sun, only 3,500 K but with a large expanded atmosphere.
References.
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