CHIMERA Occultation Constraints on the Abundance of Kilometer-scale Kuiper Belt Objects

Creators: Zhang, Qicheng¹; Hallinan, Gregg W.¹; Saini, Navtej S.^{1, 2}; Schlichting, Hilke E.³; Harding, Leon K.^{1, 4}; Milburn, Jennifer W.¹

1. California Institute of Technology
2. Jet Propulsion Lab
3. University of California, Los Angeles
4. Northrop Grumman (United States)

Abstract

Occultations provide indirect sensitivity to the number density of small Kuiper Belt objects (KBOs) too faint to directly detect telescopically. We present results from the Caltech HI-speed Multicolor camERA (CHIMERA) survey with the Palomar Hale Telescope, which monitored stars over the central 5′×5′ of the M22 globular cluster along the ecliptic plane for serendipitous occultations by kilometer-scale KBOs over 63 hr across 24 nights at a 33 Hz frame rate simultaneously in i′ and g′. We adapted dense-field photometry and occultation template fitting techniques to this data set, finding a 95% confidence upper limit on the occultation rate, corresponding to an ecliptic sky density of ≲10⁷ deg⁻² of >1 km diameter classical KBOs. We discuss a few of the occultation-like light curve signatures at the edge of the sensitivity limit responsible for setting the upper bounds, and their likely nonviability as true occultations.

Copyright and License

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

This work was supported by a grant from the Simons Foundation (668346, JPG). H.E.S. gratefully acknowledges NASA grant 80NSSC18K0828 for financial support during preparation and submission of the work.

This research has made use of observations from the Hale Telescope at Palomar Observatory, which is owned and operated by Caltech and administered by Caltech Optical Observatories.

We also thank the reviewer for providing helpful comments and suggestions.

Funding

This work was supported by a grant from the Simons Foundation (668346, JPG). H.E.S. gratefully acknowledges NASA grant 80NSSC18K0828 for financial support during preparation and submission of the work.

Facilities

Hale (CHIMERA) - Palomar Observatory's 5.1m Hale Telescope.

Software References

Astropy (Astropy Collaboration et al. 2022), Matplotlib (Hunter 2007), NumPy (Van Der Walt et al. 2011), SciPy (Virtanen et al. 2020).

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