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X-rays: Not Just For Breakfast Anymore!

Note: This was written before RXTE was decomissioned. We still provide data sets to use for these lessons, even though we no longer have live data.

Have you ever wondered what is way out in space, say 100 light years away? Some of you might think of gas, dust, and stars. Well, there are also X-rays.

X-rays tell us all kinds of neat stuff about objects ...


as close as our sun,


and as far away as 360 Megaparsecs!
(That's 1,173,600,000 light years!)



Where do X-rays come from? They come from objects that are very hot, even millions of degrees in temperature!!!

How do we look at these X-rays? Well, Earth's atmosphere is built to absorb X-rays, so if we want to observe them, we have to go outside of our atmosphere. We could send a doctor and his X-ray film out into space, but his bill would probably be a bit high. So we'll have to put a satellite into orbit instead.


As a matter of fact, there are satellites over 300 miles above us right now detecting X-rays from deep space. One of these satellites is the Rossi X-ray Timing Explorer (RXTE) and one of its scientific instruments, the All-Sky Monitor (ASM), is of particular interest to us.


The ASM surveys the sky for objects that emit X-rays. X-rays are just like the light that we see with our eyes, except they are more energetic. We say that light travels in distinct packets of energy called photons. We can use this same word, photon, to describe packets of X-ray energy.

ASM The ASM (shown to the right) has been making observations of objects that give off these X-ray photons since the mission started in 1995. An observation is made for 90 seconds and then the ASM will shift and look for another 90 seconds at a different region of the sky.

It does this all the time! It is absorbing X-ray photons while we down here on Earth eat breakfast, lunch, and dinner. So you could say it's a full-time X-ray eater! While you have been reading this page, it has probably absorbed another bunch of photons and you missed it! But that's OK, because we've kept the Data RXTE has collected in a special place, just so you can see it.

As you read, the ASM is collecting X-ray photons and updating its data on all the different X-ray sources. In fact, every three hours, RXTE sends down an update! This is the coolest part of all!

Hold on though. There is a little information that you should read before checking out the data that RXTE just sent down. If you are a first time user, you need to access the Getting Started page by clicking on the appropriate icon below. If you have already been here before, then you probably know what to do. Go to the spot that will help you the most.

For those of you who want to access lesson plans or projects right away, you can do so by clicking on the Lesson Plan icon.

Enjoy your trip through the world of X-rays and the All-Sky Monitor!

Getting Started

Getting Started
lesson plans

Lesson Plans
data access

Take Me To Your Data