Atmos extinction and AOD

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Andy Wilson

Hi Tony,

In ISIS (and other amateur packages) this is usually taken account for in the single combined step for instrument and atmospheric response correction.

The approach is take a spectrum of a standard A or B type star that has a spectrum in the Miles or similar database, and that it is at a similar altitude to your target. You use your spectrum along with the one from the Miles database to calculate a combined instrumental and atmospheric response correction. Where this won’t work is if you try to observe a target at a significantly different altitude, or if the sky conditions change. In that case you would need to take a fresh spectrum of an appropriate A or B type star.

When removing individual atmospheric telluric lines then it will be necessary to take a more sophisticated approach. ISIS has another tool which can be used for that but often this step is not needed for the target spectra. I also find this only approximately works rather than giving a really good telluric removal.