Datatype: da CCD

The Delta a photometric system has be designed by Maitzen to detect photometrically peculiar stars (Ap). The original system is based on photoelectric photometry. The da CCD system is the realisation of the original da system with a CCD detector. It uses three filters g1, g2 and y and the parameter a is defined as

a = g2 - [(g1 + y) / 2]].

Delta a is computed relatively to a linear relation : a versus (B-V) or (b-y) or (g1-y).

Record structure

No:Star number
Ref:Data source
V:V magnitude
a:a parameter
g1-y:g1-y colour index
Da:Deviation from the normal relation

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Last Update: 22 January 2006