Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mso.anu.edu.au/pfrancis/ObsTech/Ass5.pdf Дата изменения: Mon May 14 09:28:28 2007 Дата индексирования: Tue Oct 2 02:20:07 2012 Кодировка:

Assignment 5.
Due date: 4.00pm Monday 21st May Question 1: Write a computer program or an Excel spreadsheet that calculates the signalto-noise ratio reached when taking broad-band images of a point-source. Variables you will need to include are: · The filter you are using. · The brightness of the target · The diameter of the telescope's primary mirror. · The total throughput of the atmosphere+telescope (ie. the fraction of photos hitting the upper atmosphere which go on to hit the detector). · The Quantum Efficiency of the detector. You should provide me a copy of the program/spreadsheet, together with sufficient instructions on how I run it (which may be in the form of comments within the program or notes within Excel).

Question 2: Take an optical or IR image of some part of the sky. You may either use one of your own, or one I provide at the following link: http://www.mso.anu.edu.au/~pfrancis/ObsTech/data/ (this is an R-band image taken with the 2.3m telescope). Pick a fairly bright star in your image: one that has enough counts so that its signal-tonoise ratio is high, but not so many that it is saturated. Write a program to compute the amount of flux detected from this star in a circular aperture of given radius r. You will need to subtract off the sky brightness in some way to do this. Make these measurements for a number of different values of r and plot the results. You will find the tutorial listed here (and on the web page) very useful: http://www.mso.anu.edu.au/~pfrancis/ObsTech/data/ Your write-up should consist of your plot, the program, and an explanation of any tricky things you've done.