Quaoar Precoveries

What is a Precovery?

If you find a new solar system object, it is a "discovery". Since it's moving through space, you have to keep looking for it until you know its orbit around the sun well enough that you're not going to lose it. If you look for your new object after discovery, it's called "recovery". But, sometimes objects are imaged by other observers who are doing something else at the time and don't see your object. So if you find your new object in some old data that someone took before you discovered your object, it's called a "precovery". All data on this page have standard astronomical North=up and East=left.

2002 June 02

Actually, these are the discovery images. By combining the movement measured in these images with data we took over the course of a few weeks after discovery, we were able to look for Quaoar in other surveys where it was imaged but missed.

You can download the raw data from these animations here.

2001 Aug 05

These data are from the Near Earth Asteroid Tracking (NEAT) Survey. Their primary goal is to find Near Earth Asteroids, not Kuiper Belt Objects like Quaoar. But, because they archive their data in a publicly available at the Skymorph website, anyone can look for newly found objects in their dataset.

So we used the orbit fit with the 2002 data to look in the Skymorph data and found that it had been imaged in 2001. You can see that the object in the middle is there in the first image, but not the second because it moved off the image in that time. All the other stars (for the most part) stay in the same place. You can see that the comparison field is not as good as the image with Quaoar on it due to weather (cirrus or moonlight most likely).

2001 Aug 05

You can download the original images here.

2001 June 14

Using the 2002 and 2001 Aug 05 data, we found Quaoar in some 2001 June 14 data. Here you can actually see Quaoar moving over the course of the 30 minutes or so between the two images.

2001 Aug 05

You can download the original images here.

1997 Aug 01

Now, using the 2002-2001 data, we found Quaoar in some 1997 data. Quaoar is really hard to see in this one, it's just that faint smudge between the vertical pair of stars near the center which dissappears in the comparison field.

1997 Aug 01

You can download the original images here.

1983 May 17-18

So now the arc is long enough (2002-1997) that can look for it in some photographic data. Charles Kowal spend many years doing a survey of the solar system using photgraphic plates in the 1980's. His plates are ideal for trying to precover bright objects like Quaoar because he imaged each patch of sky twice over the course of two nights. It was very hard to find Quaoar in these plates, we had to spend quite a bit of time squinting through a magnifying glass to see it, but we have since digitized the images. The images below represent about 1/5000th of the entire plate. You can see Quaoar slightly above the center, and then moving to the right about 1/4 of the image.

1997 Aug 01

You can download the original Kowal data here.

Chad Trujillo
email: trujillo at gemini dot edu