Astro890_casestudy

Astro890_casestudy - Astro890 L8: So you wanna build an...

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Astro890 L8: So you wanna build an instrument? Paul Martini, May 14, 2008 Today we will cover the process of building an instrument. There are four broad steps to go from an idea to a working instrument on a telescope. These are: - Step I: Science Case, Conceptual Design, and Funding - Step II: Requirements and the Detail Design - Step III: Construction and Testing - Step IV: Commissioning Most astronomers who contribute to an instrument project will contribute at Step I, particularly with writing the detailed science case, which often turns directly into part of the funding proposal. The astronomer might also develop the conceptual design. The next most common area where astronomers may encounter the instrument is at Step IV, the commissioning phase. Those who truly consider themselves ‘instrumentalists’ will also work on Steps II and III. A subset of instrumentalists may actually do all of this work too, at least for small instruments, but for the most part instrumentalists will meet regularly with (and usually manage) the engineers, vendors, machinists, and technicians who do this work as well as determine the detailed requirements of the instrument, evaluate tradeoffs in the detail design (e.g. between cost, schedule, functionality), and help with testing before deployment. Now we will look at these steps in more detail. Keep in mind that the extent to which one needs to follow these steps is proportional to at least the square of the instrument’s cost. This means that simple & cheap instruments generally do not have a big staff and do not go through multiple design reviews, while complex instruments for large telescopes have large staffs and many many reviews, often by external committees. Step I: Science Case, Conceptual Design, and Funding Successful instruments are the intersection of what you want and what is possible. To determine what you really need (not just want), you need to understand your science case very well. To determine what is possible, you need to consider: 1) how much money you have; 2) what is physically possible to build. Examples of the second include considerations such as the materials you need must actually exist (no instrument can be built of Unobtainium), the telescope can hold the weight of the instrument, the instrument will fit on the telescope, the dispersing elements can be manufactured, etc. While a particular science goal will ultimately drive the instrument, the instrument design that emerges from Step I will usually be the result of several iterations between the science case, funding realities, and the conceptual design.
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Science Case One must have a strong case to acquire the resources necessary to build an instrument. In some cases this might not seem all that necessary, since most would say that every large telescope should have a good imager (actually one for visible wavelengths, one for NIR) and a good spectrograph (again one for each spectral region). Also, by the time the instrument is done the most interesting science case might have changed. Nevertheless,
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This note was uploaded on 07/17/2008 for the course ASTRO 890 taught by Professor Martini during the Spring '08 term at Ohio State.

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Astro890_casestudy - Astro890 L8: So you wanna build an...

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