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2008 Annual Science Report

University of Hawaii, Manoa Reporting  |  JUL 2007 – JUN 2008

The Size Distribution of Small KBOs

Project Summary

We are stacking ultra-deep images obtained using the wide-field Suprime-Cam imager on the Subaru telescope to measure the size distribution of small (~10 km) Kuiper Belt objects. Previous measurements of the size distribution have been limited to brighter magnitudes, but this survey exploits the sensitivity and wide field coverage of Suprime-Cam to reach a limiting magnitude >25 over a square degree, allowing us to study the distribution of very small objects.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

We are using the stacking techniques that we developed in our recovery attempt of 85P/Boethin for the EPOXI mission to stack four fields of Subaru Suprime-Cam data, taken over two nights. By stacking on a fine grid of rates, we will be able to detect KBOs moving at a range of orbital speeds. Our noise-suppression techniques of static sky subtraction and star-masking developed for 85/P are being used to minimize false noise detections, and cross-matching of detections between the two nights further suppresses false positives.

We then compute the true (excess over noise) detection rate using the twin null-tests of considering retrograde motion, and of perturbing night 1 in relation to night 2 to break their correspondence and leave only random matches.

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Figure 1 shows preliminary recoveries of simulated data inserted into our Suprime-Cam fields. We are able 1) to recover objects to a VR magnitude of 28 with 40% completeness; 2) to estimate the distances of the recovered objects to an accuracy of about 1 AU; 3) to achieve a small scatter in magnitude, after accounting for a systematic light loss; 4) to recover the inclination of the orbit on a coarse 5 degree grid. We are still tuning the application of the technique to the actual data, and are working to remove remaining systematic biases.

    David Jewitt David Jewitt
    Project Investigator
    Jan Kleyna
    Objective 2.2
    Outer Solar System exploration