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== Retrieving Your Data ==
== Retrieving Your Data ==
!! Notice !!
This is part of an activity that is no longer available to classes on campus.
The data we have available in response to your requests are on the server website at
You may be asked for a username and password to use the astrolab data, and if so enter
all in lower case.
However we encourage you to use the open archive of public data and select from it the best material to support your interests.
Image files ending in "fits" must be downloaded to view in AstroImageJ, ds9, or Aladin. Other files may be viewed on the web.
Find an image file and right click on the name. Save the data to your own computer for use later. The "fits" files are astronomical image data types and usually very large so download will be slow. ImageJ is generally useful for all types of images, but you may find that ds9, which shows only astronomical FITS images, is a tool you like as well. Use what works best for you.
AstroImageJ allows you to view files of all types. It is particularly good for working with all astronomical image data. You can experiment with it -- the difficulties of software are part of the lab experience!
AstroImageJ is installed on the computers in the astronomy lab. If you prefer, to run a version on your notebook you may click below to go to the link
for a version you can download to run on Windows, Apple, or Linux computers.
Once AstroImageJ has started, select "File" from its menu, "Open", and find the images you have downloaded. You might review your work other lab activities to see what the different controls will do.
AstroImageJ offers many image processing options, and allows you to build color images from individual images in each color. You could also use Aladin or SAOImage ds9 for viewing images, but they are less versatile for processing the images and making measurements.
SAOImage DS9 is an astronomical imaging and data visualization program that is widely used for research. It is installed on the lab computers and you may find it the best way to view and measure astronomical FITS files. It is free software, and can be installed on Mac, Linux and Windows computers if you prefer to run it on your own. It is not a web application, and the files you use it with must downloaded to your computer first. For more information if you are working outside the lab, go to this link
Aladin is ideal for viewing most fits files because it handles astronomical coordinates, and also allows you to overlay images from different sources. However, it does not do image processing particularly well, and if you want to modify an image a lot you may need ImageJ. The link to Aladin is
Use "File" and "Open local file" in the Aladin menu to view an image you have already downloaded. You may install Aladin on your computer. It is safe, free, and reliable.
Although the software will run on your notebook or home computer, and the data are available over the network, we ask that you do the work in the lab so that the assistant can help, and you can discuss your ideas with other students. You must submit your results in the lab that day.
If you submitted a request for data, we have tried to get it for you this semester. In some cases the requests could not be met because the objects were too bright (a very bright star for example), or too close to the Sun to view at this time. Also requests for objects in the solar system would usually duplicate our scheduled recording of the bright planets and asteroids. For these lab activities we have combined our most recent data in the archive indexed by object name, and dates. You can access any data in the archive by following the link given above.
Look at what is available, think about what you asked for, and decide what question you want to explore. If you did not submit a request, or if the data you hoped for are not available, think over the possibilities, pose a new question, and use what you have.
You might begin by comparing the data with what you can find on the Internet too, perhaps in Wikipedia or an image search, but remember that the focus should be on the data from our telescopes. It will be quite different from the pretty pictures you may get from the Hubble Telescope or press releases from ESO.
To give you some ideas, here are questions you might seek answers to:
In Messier 1, there are two central stars. Which one is a Pulsar? Does it have a different color from the other one. Why are the filaments red? Why is the fuzzy nebula "gray"? If this is the remnant of a supernova that occurred in 1054 AD, what is its 3-dimensional shape (you are only seeing it projected onto the sky)?
In NGC 7662, what 3-dimensional shape could make the object look like this? There are images taken in filters isolating light from hydrogen, sulfur, and oxygen. Is there a difference in where these features appear in the nebula? Measure how large NGC 7662 is in diameter on the sky (an angle), and look up its distance with help from Google. See if you can figure out how large in diameter it must be compared to our solar system. (Your assistant may help if you get stuck.)
For the Pleiades, Messier 45, how would you decide the distance to the stars, and how will that distance affect their appearance in the images?
For the Moon, look for famous named craters. Find Copernicus, Tycho, Plato, Mare Imbrium, the lunar Appenines, and Sinus Iridum. How big are they? That is, how many kilometers across are they? Why are shadows longer for craters and mountains close to the "terminator", the line that divides the light and dark sides. Are the craters that are near the top or bottom (north or south) really oval, and if not, why do they appear to be oval? How did the floor of Mare Imbrium or of Plato become so free of craters? Find other images of the Moon on the web and compare them to this one. Can you see more or less of the Moon toward the edges of the disk? Why is that?
This unit is an open ended inquiry. Start with the data we have provided and see where it takes you. Describe what you did and your conclusions in your response. Remember that typically discovery-based science generates new questions, and you may suggest other inquiries as part of your conclusion. Even if you work in small groups in the lab, each student must submit their own work at the end of the lab period.