and Cosmology

A.4 The Magnitude Scale
Fig. A.2. Transmission curves of various
filter-detector systems. From top to bottom:
the filters of the NICMOS camera and
the WFPC2 on-board HST, the Washington
filter system, the filters of the EMMI
instrument at ESO’s NTT, the filters of
the WFI at the ESO/MPG 2.2-m telescope
and those of the SOFI instrument at the
NTT, and the Johnson–Cousins filters. In
the bottom diagram, the spectra of three
stars with different effective temperatures
are displayed
421
Table A.1. For some of the best-established filter systems – Johnson, Strömgren, and the filters of the Sloan Digital Sky
Surveys – the central (more precisely, the effective) wavelengths and the widths of the filters are listed
Johnson U B V R I J H K L M
λ eff (nm) 367 436 545 638 797 1220 1630 2190 3450 4750
Δλ (nm) 66 94 85 160 149 213 307 39 472 460
Strömgren u v b y β w β n
λ eff (nm) 349 411 467 547 489 489
Δλ (nm) 30 19 18 23 15 3
SDSS u ′ g ′ r ′ i ′ z ′
λ eff (nm) 354 477 623 762 913
Δλ (nm) 57 139 138 152 95