skendrew edited this page Sep 14, 2010 · 4 revisions
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Welcome to the Wiki for the midIR_sensitivity repository.

What’s in the repository?
The repository contains IDL code and input files to calculate the likely sensitivity of a ground-based astronomical instrument for mid-infrared wavelengths. By mid-infrared I mean within the atmospheric windows from 3 to 14 microns, commonly referred to in astronomy as the L (~3-4.2 microns), M (4.5-5.5 microns) and N (7.5-14 microns) bands.

The code was developed for METIS, the proposed mid-IR instrument for the 42-m European Extremely Large Telescope, and the input parameters reflect this. By using separate parameter input files, I hope I’ve made the code relatively easy to adjust for your own purposes. The calculation process for signal to noise and sensitivity, as I’ve outlined in the enclosed tech note, is rather “universal” and the code can demonstrate a way of implementing that for a real instrument.

A few words of caution…
1. A computer programme is only as good as the stuff you put in. There is no one “right” way of performing these calculations, and I make no claims that mine is the best method. I don’t even guarantee that I’ve made no mistakes (although I’ve spent a considerable effort testing, cross-checking, testing, debugging, testing again etc). If you find any, let me know!
2. The inputs into this code are highly tailored to the optical design and observing conditions of METIS on the E-ELT. While I’ve tried to make it easily customisable with the parameter files, adapting it for your own project will require a considerable effort. If you have questions about how or why I’ve done something, drop me an email.
3. This may be obvious but I should point it out anyway. In 2008-2009, METIS is a conceptual instrument for a conceptual telescope. This model calculation, while based on experience with real telescopes and instruments, has not been and cannot be verified against observations with the actual instrument. This is another reason to care when interpreting your results.

Future development
The code was developed during the Phase A study of METIS, which ran for 18 months in 2008 and 2009. Whether METIS will progress to further stages will be decided in mid-2010. If it does, the optical and mechanical design of the instrument may well change. I will not be involved in the project at this stage so what will happen to this code is uncertain. Check the METIS website for project updates.

Got suggestions? Feel free to post them here…