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Kuiper Belt Observations, 15-9461

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Principal Investigator
Joel Wm. Parker

Inclusive Dates:  02/12/04 - 06/12/04

Background - In 1992, a new and fascinating area of planetary astronomy opened up with the discovery of the first recognized Kuiper belt object (KBO), 1992 QB1. The existence of the Kuiper belt - a reservoir of icy asteroid-like bodies left over from the formation of the outer solar system in the region beyond Neptune - was predicted throughout the 20th century. The discovery of 1992 QB1 and subsequent objects brought new excitement and funding into this field of research, generating widespread support from ground-and space-based observatories as well as NASA missions. The study of the Kuiper belt has ramifications well beyond simply exploring a newly discovered and mostly unknown population of the solar system; the Kuiper belt houses a vast reservoir of these interesting small bodies and is supplying important new clues to the formation of the outer solar system. An important factor in Kuiper belt studies is having accurate measurements of the orbits of KBOs.

Determining accurate orbits requires intensive commitment of research and observing time to make the necessary measurements. However, these objects are extremely faint (well over a million times fainter than can be seen with the unaided eye) and moving, and thus are very difficult to observe. Owing to these challenging observational demands, follow-up observations have not occurred often enough to prevent "losing" a significant number of these objects. When KBOs are lost, so is the vital information they would have provided for further scientific analysis.

Approach - To advance our understanding of the Kuiper belt, we have identified three core issues that need to be addressed:

  • Well-determined orbital elements of KBOs are essential for providing an accurate view of the Kuiper belt's physical properties such as dynamics, formation, and structure;
  • A program of dedicated follow-up observations of KBOs is absolutely necessary to obtain an unbiased collection of objects with well-determined orbital elements; and
  • Such recoveries are most effective when they are coupled to a well-characterized discovery program.

To address all those issues in this project, we have developed a collaboration with Kuiper belt observers in Canada and France to make recovery observations of KBOs discovered by the new CFHT Legacy Survey (CFHTLS; CFHT is a telescope on Mauna Kea in Hawaii at one of the world's premier observatories). Our project will be an important part of a coordinated and integrated international observing effort. The resulting well-characterized database of approximately 1,000 KBOs will allow us and other researchers to determine the dynamical structure and distribution of the Kuiper belt, identify intriguing objects for further observations and analysis, and provide accurate orbital elements so that objects will not be lost for subsequent physical study. Our ultimate goal is to understand and map out the formation history of the outer solar system.

To this end, we proposed to the National Optical Astronomical Observatory at Kitt Peak Observatory in Tucson, Arizona, for observing time to perform recovery observations. In December 2003, we were informed that we were awarded two observing runs on the two largest telescopes at Kitt Peak: three nights (Feb 18-20, 2004) on the 3.5-meter WIYN telescope and three more nights (May 23-25, 2004) on the 4-meter Mayall telescope. This award is a significant external contribution of support for our project, and a peer-reviewed validation of our plans and goals. However, awards of observing time do not include any funding for the researchers, so this quick-look internal research project was proposed to support the significant amount of time required for the preparation, execution, and analysis of the observations.

Although internationally recognized for his observations of KBOs, Dr. Parker's collaboration with the CFHTLS is new. In the previous year's proposals to NASA and NSF, although the review panels explicitly positively cited Dr. Parker's past experience and ability for this type of research, he was not awarded funding because the panels were not convinced that the CFHTLS could produce the claimed goals. At that time, the CFHTLS had only just begun; now that it is underway, the expectation is that the success of these SwRI-supported observing runs at Kitt Peak will provide us with proof-of-concept of our observing strategies and the project's capabilities. That success will establish a foothold for us to obtain further observing time and significant external funding to continue this project.

Accomplishments - We performed both observing runs at Kitt Peak National Observatory. It is expected that typically 20 percent of awarded observing time can be lost as a result of weather or instrument problems. We were particularly unfortunate that a majority of our observing time was lost as a result of high winds or clouds, often both in the same night. However, in spite of that, we were still able to observe and obtain measurements for several important objects. This success showed that we were able to make high-quality observations even in marginal conditions and work efficiently even with weather significantly chopping-up and reducing our observing time.

The work associated with each observing run included:

Preparation: selection of targets in collaboration with the CFHTLS team, creating the finder charts that show the objects' expected positions in the sky, and uploading coordinates to the observatory computers.

Execution: travel to and from the observatory, 3 nights of observations, initial data verification and processing during the observing run.

Post-observation analysis: final processing of images, identification of KBOs, measurement of positions on all images, further analysis of the objects (e.g., search for binary objects), distribution of data to the CFHTLS team, and publication of results in the International Astronomical Union and Minor Planet Electronic Circulars.

One of the objects we recovered, 2003 FC128, was of particular interest because other KBO researchers had observed this object, but obtained unusual and conflicting results. Our observations were able to recover this object successfully, and our high-quality measurements were essential to determine its orbit correctly. This object is now identified as being in the 4:5 resonance with Neptune (it orbits the sun four times for every five times Neptune orbits the sun), an orbit not well-determined until we provided our measurements.

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