Relative sizes

Kuiper Belt Object

2005 UB313

August 2005

Relative orbits

This page created 09 September 2005

The image below and to the left is a CCD image of the recently announced Kuiper Belt Object (KBO) and potential "10th planet" candidate 2003 UB313 taken on August 8th. The image consists of eight 30 second exposures that have been stacked using the AIP4WIN software. A Meade LX200 F/6.3 SCT coupled with an SBIG ST-9XE camera was used to take the shots. UB313 is indicated with the red arrow. It is almost indistinguishable from some of the defects in the image that I am attributing to a poor flat field used to process the individual frames. The non-uniform background is also a manifestation of this poor flat fielding. There are enough spurious pixels that by itself this image is not as convincing a picture of UB313 as I would like. However, the arrowed star-like point is within a fraction of a pixel of where UB313 should have been at the time the pictures were taken. (The image scale is roughly 2.3 arcsec/pixel.) In addition, comparison with an online image (shown on the right) shows no object at that point, even though it registers stars of comparable magnitude. UB313 itself is roughly magnitude 18.7.

The streak in the left imageis a satellite that passed through the field of view on one of the exposures. Presumably the streak in the right image is also a satellite. The white area in the corners of the right images are an artifact of my having rotated the image to match the orientation of mine. Clearly the atmosphere was a lot more turbulent when I took my picture, then when the web comparison picture was taken. In case you're wondering, I took only 30 second exposures because my telescope was mounted on an alt-azmith mount. This means that I have field rotation, and more important, I can't engage the periodic error correction mode on the scope drive (the later models supposedly do have this feature available in alt-az mode). For some reason, I also haven't been able to get the ST9-XE to self guide - and I haven't had time to play with it.

By clicking on the two images bracketing the web page title above give you can get an idea of both the size of UB313 relative to other recently discovered solar system objects (photo from Sky and Telecope), and their orbits. For further information peruse the web pages of the group that discovered UB313:

August 8 CCD image of UB313
Internet image of UB313

In case you are wondering where astronomers come up with such an archane name as 2003 UB313, the designation comes about as follows:

1) The 2003indicates the year of initial discovery. So even though this object was announced in August 2005, it was actually discovered in 2003.

2) A blank space always follows the year.

3) The U indicates that the discovery was in the second half of October. The letters are assigned as follows:

Month--> Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
First half A C E G J L N P R T V X
Second half B D F H K M O Q S U W Y

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