\ PHY 515: Archival Data Analysis Project

Archival Data Analysis Project


Goals of this project

Grading Policy
The grade will be based on

I. Introduction

The primary role of a scientist is not to solve problems, but to ask questions that can be solved. A good scientist then goes out and solves those problems. The purpose of this lab is to permit the student who has some astronomical background to select (or perhaps to create) a problem of his or her own cloosing, and then to attack the problem with existing archival data.

There are few guidelines, hence this exercise is inappropriate for students who have no astronomical background. The research need not be original - there are few worthwhile, truly new projects that can be done in 3 weeks. Rather, select some known target and undertake a basic investigation.

The first task is to identify a problem which can be solved by using data in the NASA archives. There are no limitations to the scope of the problem, except that you must be able to explain succinctly the problem, and how you will solve it, and then you must do so within about 3 weeks. You can either undertake a comprehensive analysis of a single data set, or a less detailed multi-wavelength investigation involving 2 or more data sets.

You may analyze images, spectra, or photometry. Your analysis may be astrometric, spectroscopic, or photometric in character. You may undertake temporal variability studies, determinations of the properties of a class of objects, or comparisons between objects.

Be aware that different missions archive data in different stages of readiness. Also, your instructor and TA may be vell versed in handling some types of data, and completely ignorant of others. You are facing exactly the same problems that any professional astronomer faces in dealing with a new kind of data set.

You should read the page on astronomical instruments. This will give you some idea of what types of data are available in the archive, and may help you decide what to investigate.

Example Projects

Spend a few days examining the available data, and crafting your problem. Then write a one page proposal to your instructor explaining the problem and how you will use archival data to address it. The proposal must outline the method you will use to solve the problem, and must indicate what data you will be using. The purpose of the proposal is to insure that the problem is tractable.

Because of the limited amount of time available to do the lab, you need to hand in your proposal no later than the second lab period. You should be thinking about a project before the lab begins, and then spend the first lab session examining the available data.

Your second task is then to download the data. After this, analyze what you need to and then write up your results in the format of an ApJ Letter (9 or fewer double-spaced typed pages, plus figures). Easy, eh?

II. The Archives

There are three major archives sites you should check out.

IIa. Specific Data Sets

This is not meant to be an inclusive list of data sets, but represents some of the data which you may find most useful. Do not limit yourself to these datasets, but explore the archives if these data do not include what you want.

If you cannot find what you are looking for at one of these sites, it is probably not available. Note that most data taken at ground-based telescopes (KPNO, CTIO, Keck) are not formally archived. Solar data are generally archived. Radio observations from the VLA are, but if you want to work with these data you are on your own.

III. Downloading Archival Data

Data may be downloaded in a variety of ways. The archival sites listed above will give you various options. The most common are:

Recent datasets (especially Hubble Space Telescope data) can be large, and can take some time to transfer. Transfers often go faster in the morning (before the west coast wakes up) or after 5PM.

IV. Reading Archival Data

Most of the archival data is stored in FITS format. These data are easily readable in either IDL or IRAF.

The data are often stored in compressed mode to save disk space and decrease downloading time. Compressed data have filenames ending in .Z (UNIX compression) or .gz (gzip compression). The WinZip utility on the PC can be used to uncompress data.

V. Analyzing your data

Once you have your data in FITS format, you can read it using IDL. Then, analyze your data. A short tutorial on how to do basic tasks in IDL is here.

VI. Writing up your results

"Our only product is paper" (J.L. Linsky)
is a somewhat outmoded, but still apt, comment on science.

You are to write up your results in a the format of an Astrophysical Journal paper. A standard layout is:

Be sure to include references to the literature, and figures and tables as appropriate. If you write IDL procedures (or other code) for the data analysis, please include the code as an appendix.

If we get LaTeX running on the PCs, then you will be expected to write your paper in AAS TEX format. Instructions will be forthcoming.

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