The zero magnitude of a given ISOPHOT filter is defined as the signal of the `ideal' (i.e. model) Vega which would have been measured in that filter with an infinitely large aperture.
The ideal spectrum of Vega was derived from a Kurucz model with
= 9400 K , log(
) = 3.900, metal poor,
0.0 kms
and no infrared excess due to circumstellar
dust, extended to 300
m and absolutely calibrated as described by
Cohen et al. 1992, [6],
and Walker & Cohen 1992, [55].
The magnitude can be obtained from the PHT
auto analysis data product by applying the relation:
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(D.1) |
where
is the AAR flux density.
The values for
with filter identifier and
reference wavelength
are listed in
Table D.1.
For completeness, we have included in Table D.1
the corresponding powers on the detector
,
the ideal Vega flux density at the reference wavelength
, and the colour correction
.
can be applied to the SPD products, thereby
taking into account the point spread function correction, see
Equations 5.8 and 5.9. The
values of
are very close to the ones which have been derived for a
10000 K blackbody, see Table C.2.
filter |
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ID | [![]() |
[W] | [Jy] | [Jy] | [ ] |
P_3.29 | 3.3 | 4.60E![]() |
312.0 | 318.2 | 0.981 |
P_3.6 | 3.6 | 2.15E![]() |
284.7 | 270.9 | 1.051 |
P_4.85 | 4.8 | 1.24E![]() |
163.2 | 152.1 | 1.072 |
P_7.3 | 7.3 | 1.01E![]() |
79.96 | 71.09 | 1.125 |
P_7.7 | 7.7 | 1.61E![]() |
65.14 | 64.23 | 1.014 |
P_10 | 10 | 1.77E![]() |
39.40 | 38.60 | 1.021 |
P_11.3 | 11.3 | 3.94E![]() |
29.96 | 30.40 | 0.985 |
P_12.8 | 12.8 | 5.71E![]() |
35.47 | 26.97 | 1.315 |
P_16 | 15 | 1.26E![]() |
24.21 | 23.79 | 1.018 |
P_11.5 | 12 | 5.46E![]() |
17.25 | 17.40 | 0.991 |
P_20 | 20 | 5.17E![]() |
9.940 | 9.840 | 1.010 |
P_25 | 25 | 3.47E![]() |
8.109 | 6.307 | 1.286 |
P_60 | 60 | 7.29E![]() |
1.233 | 1.087 | 1.135 |
P_100 | 100 | 3.55E![]() |
0.4068 | 0.3866 | 1.052 |
C_50 | 65 | 5.76E![]() |
1.197 | 0.9245 | 1.295 |
C_60 | 60 | 7.60E![]() |
1.153 | 1.087 | 1.061 |
C_70 | 80 | 5.22E![]() |
0.7489 | 0.6075 | 1.233 |
C_90 | 90 | 8.45E![]() |
0.5597 | 0.4787 | 1.169 |
C_100 | 100 | 4.03E![]() |
0.4261 | 0.3866 | 1.102 |
C_105 | 105 | 2.25E![]() |
0.3683 | 0.3503 | 1.052 |
C_120 | 120 | 1.15E![]() |
0.3253 | 0.2672 | 1.217 |
C_135 | 150 | 1.32E![]() |
0.1862 | 0.1698 | 1.096 |
C_160 | 170 | 1.60E![]() |
0.1587 | 0.1316 | 1.205 |
C_180 | 180 | 6.92E![]() |
0.1288 | 0.1172 | 1.099 |
C_200 | 200 | 2.27E![]() |
0.0972 | 0.0945 | 1.028 |