Today’s computer technology, modern optics, and electronics allow astronomers and students to "see" the sky without enduring long freezing nights looking through an eyepiece. The data we acquire are quantitative measurements of how much light arrives from fields of view that can be tiny and cover only a few stars, or vast, and cover constellations. They can tell you the positions of moving objects, the variations in their brightness, their colors, details of the structure, and how they interact or relate with nearby companions. Modern astronomy is evolving in the development of a new class of very large telescopes that by mid-2020's will have public data over the entire sky updated almost nightly. Smaller telescopes and instruments in space follow up on the discoveries offered by these big telescopes with closer inspection and careful analysis.
If you are interested in this future world, you can read more at websites for Gaia, a new satellite beginning to return amazing measurements of distances throughout our own galaxy, and of LSST, a "synoptic survey" telescope under construction in Chile.
The University of Louisville and the University of Southern Queensland operate remotely controlled telescopes at Moore Observatory near Brownsboro, Kentucky, at Mount Kent Observatory near Toowoomba, Australia, and on Mt. Lemmon in Arizona. For more than 10 years we have been acquiring data for research and student use, and we have an archive of many of the bright objects that may interest you. This semester our telescopes in Kentucky, Arizona, and Australia are operating robotically under the supervision of professional astronomers and can also acquire new images to meet your requests as well.
This week your lab activity is to thoughtfully identify something in the sky that really grabs your interest. It can be anything, but because there are limitations on what we can observe we will make a few suggestions to guide your thoughts. With that, ask some questions yourself -- we are reversing roles here! Why would you like to see this object, and what would you like to learn about it that a telescope image or measurement could reveal?
The observatories are described on our website at
and you are encouraged to explore it to see about the observatories and their telescopes. The content is currently under development, and may change during the semester.
The facilities we have access to include:
At both observatories we have identical 0.5 meter (20 inch) diameter "CDK20" research telescopes operating with a CCD camera and a selection of filters. These are the primary telescopes for this program. We offer other instruments too, and we are developing the capability to have you visit us through the web when the telescopes are in operation and to press the "shutter button" yourself. For example there are
Also we have a substantial improving archive of the best images that we add to often. We will draw from it when we can to satisfy your requests.
Except the color cameras used to record wide field images of constellations and the occasional comet, the CCD cameras on the telescopes return scientific images as digital files in “FITS” format. These images may be viewed in your computer's browser with some tools we will provide, or with other software you load on your own computer. those images require some effort to analyze, but they offer quantitative data on positions and brightnesses. Over the next few weeks you will be using some of the software that is needed and gain experience with what it can do.
In many cases we will produce color images from these data that may be useful if you are interested in seeing form or structure, watching craters or shadows on the Moon, following the rotation of Saturn, Jupiter or Mars, or looking for the colors of stars. The color images often are not "true" color but a combination of different filters to highlight some aspects of the objects of interest. You can make them too by working with the original data.
Except for the special wide field cameras, these telescopes cover a field less than about half a degree across, the apparent size of the Moon. Each pixel resolves about 0.5 arcsecond (there are 3600 arcseconds in a degree), and measures how much light arrived at that spot in the image for the duration of the exposure. By comparing one pixel with another, you can tell how much brighter or fainter one feature of the image is compared to another. The image that you see, while visually exciting, is also a tool to measure how much light there is and where it is.
Some images may be returned to you with a calibration for the position in the sky, and as you explore them you can measure the celestial coordinates of any point in the image. In this way, you can identify individual stars, clusters, nebulae, and galaxies in the images. You can follow the changing positions of asteroids and satellites of planets. You can spot a new supernova, watch variable stars, measure the separation of double stars, measure the diameter of a distant galaxy, or follow a new comet.
With the scientific cameras each image is taken through a filter that isolates a narrow band of the spectrum by passing the light through a filter that removes all but the part we want to record. If you looked through one of the filters, you would see only part of the light that is collected by the telescope. A "blue" filter would should light our eyes sense as blue, while an "infrared" filter would should light our eyes cannot see at all. Here’s how we designate the filters that are usually available by the wavelengths they transmit:
The numbers are the wavelength of light in the spectrum, from blue light at 450 nanometers (nm) to red light at 650 nm (nm). Infrared has a longer wavelength than red, and ultraviolet has a shorter wavelength than blue. Since our telescopes respond well to "near" infrared light, out to 1100 nm, but not well to ultraviolet light, we observe in the bands that are most efficiently detected by the optics and electronics.
A measurement with different filters allows us to determine the “color” of a star, or we can put images from blue, green, and red together to make a color image that will resemble what you would see if your eyes could detect this faint light. Images through a filter that isolates light emitted by hydrogen gas would show few stars, and if you could "see" through this filter the scene would look dark red and show only the gas. You may read more about all the filters that are available here.
The faintest stars you will find in most images are about 18th magnitude. These stars are more than 10,000,000 times fainter that the brightest stars in the night sky. Typically the telescoped cover a field of about 1/2 degree, the diameter of the full Moon, but in some cases it can be smaller to see very fine detail,or larger, to get an entire constellation or a big comet. If the air is steady, the smallest detail you will see is about 1 arcsecond across. For comparison, Jupiter appears about 40 arcseconds across in our sky, and the Andromeda galaxy extends thousands of arcseconds. Some of our planetary and lunar images show detail as small as 0.3 arcseconds, the resolution limit of our telescopes in perfectly stable air.
Within our solar system you could expect to see
Within our Milky Way galaxy you could see
Beyond our galaxy there are
However, what is available to see depends on the time of year (where Earth is in its orbit), where the planets are in their orbits, and whether you are using a telescope in the northern or southern hemisphere.
If you are in the astronomy lab on campus and working in a small group (usually 3 students), you may make a decision as a group about what to request. This is easiest for us too, since we have fewer requests to handle that way. However, if you prefer you may work on your own too.
This project has two parts that are graded separately. The first part you need to do this week is to define a problem and propose an observation. After that, we will find data for you in our archive, or even acquire data with our telescopes over the following weeks. Once we have something useful, we will provide it to you and, where you need it, assist you with understanding what it has to offer. Our expectation is to have data back to you in early April, and the last activity of this semester will be to tell us what you can find in it. When the data are available there will be an announcement, probably a comment on the discussion forum, and the last activity page will open up on the class website too.
The first big step is to decide what you would like to do. Almost always, this is a very challenging exercise because there is so much to chose from. There is no right answer. Here is a guide to help you think about it. Also, before submitting your request, we welcome a discussion on line or email if you need advice.
What would I like to know more about that I could expect to “see” with one of these telescopes?
Our telescopes can provide data allowing you to measure how stars vary in brightness ("variable stars"), to follow the motions of satellites of Jupiter, Saturn, Uranus, and Neptune, track asteroids, and capture the latest new supernova or recently discovered comet. When the skies are dark and the Moon is not out, they can record faint nebulae and distant galaxies too. We offer views of the clouds of Jupiter and the rings and atmosphere of Saturn in better detail by selecting the very best images that are not blurred by Earth's atmosphere. Our wide field telescopes show faint nebulae and star clusters that span several degrees on the sky.
Use your imagination!! Satisfy your curiosity by selecting an object or objects, and the sort of data you would like to have on it. Once you have made a decision, you have to submit your request so that we know what you want, and you have to answer questions about your request.
First, check that the object of interest is visible to us now unless you want what we already have. Indeed, our best planetary images are ones we have selected from among thousands taken, so even if a planet is not favorably placed now we can probably offer something. However currently the choices in our own solar system are
You might use Stellarium, for example, to see what is in the sky now and later this spring, or the on-line tool n-the-sky.org. Sky-Map and Aladin-Lite will let you explore images and data from professional observatories on the web. You could also use Google simply to search for more information about your proposed target. If your request is inappropriate for what we can do, we will work with you to help refine your selection.
We will make the selection of the telescope and other resources for you based on what you tell us about your request. For example, if it is well below the celestial equator and seen only in the southern hemisphere we will use a telescope at Mt. Kent, and if it is better seen from the northern hemisphere, we will use one of the telescopes at Moore Observatory in Kentucky. The Moon, Jupiter and Saturn are best recorded with the special purpose planetary telescope at Moore Observatory. Objects that cover a wide area of sky may be better seen in the wide field telescope or even the color cameras, but most requests will be directed to the 20-inch "CDK" telescopes. You are welcome to request a specific telescope and if it is available and appropriate we will try to use it for your data.
Complete the simple form at the link below.
We use your responses to schedule our telescopes, so please complete it while you are in the lab. Make a note to yourself of your request, and keep some notes about what you responded since they will help you complete the second part later. If you are working with others we only need one on-line request. In the comments section, if you note who is working together it will simplify sorting out the requests and responses later.
For this lab we need the following from each student:
For this lab it will help us a lot if you put your preferred email address on the form you submit to the assistant, and list the names of those who are working with you on this. Should groups re-organize later in the semester or you find your self working with someone else, this will insure we can get data to you.
After you have submitted the request, then each student should answer the questions asked here on the usual lab response form and and give them to the lab assistant. He may have an immediate suggestion about your choice and you probably should discuss it with him before you get to this last step. Remember that we need both the answers from you on the usual lab sheet, and the completed web submission from your group while you are in class today.
Once your data are available we will provide a link from which you can download images and there will be another activity in class for you to use in completing the work. Expect it in early April, or before if the weather is good to us.