Total (asymptotic) U magnitude
The U-band magnitudes are computed from the photometric measurements compilation
(table a107) and from U-B colour index from the
colour catalogue (table a112) combined with bt.
Colors are given essentially in the UBV system. They are :
- total asymptotic colors ubt
for (U-B)T
- total asymptotic colors bvt
for (B-V)T
- effective colors ube for
((U-B)e (colors within the effective aperture in which half the total
B-flux is emitted)
- effective colors bve for
((B-V)e (same as for ube)
Total assymptotic colors bvtc
and ubtc are corrected for
galactic extinction, inclination and redshift effect (see e.g. btc documentation).