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Mean photometric error
Photometric measurements are affected by observational errors that here are modelled following a Gaussian distribution.
The user can fix a 1 sigma constant error
that is applied to all stars in the simulation for all 9 photometric bands.
Another option is to employ an error that varies with the actual star magnitude and/or photometric band.
The exact values have to be specified in an appropriate table. This table contains 18 columns.
The first 9 columns display magnitudes in the 9 photometric bands, in order of increasing values.
The remaining 9 columns are the corresponding photometric errors.
An example is the following:
| Mu |
Mb |
Mv |
Mr |
Mi |
Mj |
Mh |
Mk |
Ml |
sMu |
sMb |
sMv |
sMr |
sMi |
sMj |
sMh |
sMk |
sMl |
| 3.0 | 2.5 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 0.02 | 0.01 | 0.01 | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 |
| 5.0 | 5.1 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 0.02 | 0.01 | 0.02 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 |
| 8.5 | 7.5 | 8.5 | 8.5 | 8.5 | 8.5 | 8.5 | 8.5 | 8.5 | 0.03 | 0.02 | 0.02 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 |
| 10.0 | 9.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 0.04 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 |
Let's assume a synthetic star has U and B magnitudes equal to Mu=6.0 and Mb=4.9. The program searches for the pair of
tabulated U and B values that bracket the star's magnitudes. In case of the U band these two values are 5.0 and 8.5. In case of the B band
this pair of tabulated values are 2.5 and 5.1. The 1 sigma error assigned to the star is the value corresponding to
larger of the two bracketing magnitudes. This means that the error in U will be equal to 0.03 mag (corresponding to the tabulated
U=8.5 value) and the error in B will be equal to 0.01 mag (corresponding to the tabulated B=5.1 value).
The allowed range of the 1 sigma dispersion in any band is 0.0 - 1.0 dex.
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