Catalina Outer Solar System Survey

Welcome to the outer solar system!

Here, you will be looking through archival data from the Catalina Sky Survey (CSS) in an attempt to discover new Trans-Neptunian objects (TNOs).

CSS is relentless when it comes to scanning the night sky for asteroids that come close to our planet. From the mountain peaks of southern Arizona, CSS operates almost every clear night making real time discoveries, and has been doing this since 1998.

CSS can find dozens of Near-Earth Objects (NEOs) in a single night by looking for objects that move within a sequence of images taken over several minutes. However, NEOs are much closer than TNOs, and therefore in these images TNOs do not appear to move at all. The timescale of minutes is far too short to detect any motion from these distant worlds.

However, using the same night-time field images acquired over several months enables us to detect the motion of TNOs!

Why are we using CSS images to search for TNOs? Unlike other surveys for TNOs and other distant objects, CSS covers more than half of the total sky instead of only small bands near the ecliptic. This wider view is where unknown objects with larger orbital inclinations and other oddities can be found.

How can I find a TNO?

Want to know what it takes to explore the farthest reaches of our solar system? Lots of work goes into the process, but the final step is up to you! Let's walk through the process of finding a TNO to see exactly where you fit in. Below are two images taken from one of the CSS telescopes of the same place in the sky about a month apart.

Can you see two tiny green circles? Don't worry if you can't. Lots of computer processing went in to identifying an object that isn't in the same place in the two images. That would be almost impossible for a human. Lets zoom in below for a closer look.

You can probably now see the two green circles. There are also two yellow circles to show where the object is in the other image. This helps us see more clearly that the object has moved. This is a great start! But if we just look at two images, we tend to find lots and lots of false detections. To help with that, we look at four images. The likelihood of four random smudges, cosmic rays, or image artifacts lining up perfectly across months of time is much less than for two images. However, four images this big is still a LOT of cosmic real estate to look at! To help out, astronomers like to animate the images. That way, real objects look like they are moving. Below is an animation of the first two images plus two more. They were all taken about a month apart from each other.

This is STILL a lot to take in. Especially if the object we are interested in has moved even further than this one. Then we would be zoomed so far out to see the whole path the moving object that we wouldn't be able to see the object, it would be too tiny in the images. Most of this image is excess space, made up of the large gaps between the objects positions. We really only care about the small space where the object would appear from image to image. So we have cut out small squares of the images, and put them right next to each other. This is what it looks like:

This is where you come in! We need you to sort through these animated images, and help us identify which ones have REAL objects like the one above! Now this is an example with a very BRIGHT and well known TNO named Makemake. Most of the new ones we detect will be much fainter. When you are ready click the Classify tab to start. A tutorial will start automatically for your first time. Once you are in the Classify tab, you can always review the tutorial by clicking the tutorial tab.