Astron. Astrophys. 349, 649-659 (1999)

CCD photometry of distant comets

S.C. Lowry ¹, A. Fitzsimmons ¹, I.M. Cartwright ¹ and I.P. Williams <sup>2

1</sup> APS Division, Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, UK
² Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, Mile End Road, London E1 4NS, UK

Received 25 January 1999 / Accepted 19 July 1999

Abstract

While it is apparent that many comets are active beyond the canonical distance of 3 AU, few surveys of cometary activity have been performed in this region previously. Such a survey enables a more accurate determination of the proportion of comets that exhibit little or no outgassing at these distances. Results are presented of CCD observations of comets in the region of 3 AU R_h 6 AU obtained with the 1m JKT on La Palma. Photometric observations of 15 comets were obtained, 7 of which displayed coma activity and 8 of which appeared inactive. BVR photometry was performed on these comets to determine dimensions, colours and outgassing rates. Although 40P/Vaisala 1 and 26P/Grigg-Skjellerup were not detected, upper limits to their nuclear radii are presented. The results obtained are compared with previous observations.

Key words: techniques: photometric comets: general

Send offprint requests to: Stephen.Lowry@qub.ac.uk

Correspondence to: Stephen.Lowry@qub.ac.uk

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. Observations and reduction
• 3. Results and analysis
  • 3.1. Undetected comets
  • 3.2. Unresolved comets
  • 3.3. Active comets
    • 3.3.1. 119P/Parker-Hartley
    • 3.3.2. 32P/Comas-Solá
    • 3.3.3. 74P/Smirnova-Chernykh
    • 3.3.4. P/1993 K2 (Helin-Lawrence)
    • 3.3.5. 9P/Tempel 1
    • 3.3.6. 89P/Russell 2
    • 3.3.7. 87P/Bus
• 4. Discussion
  • 4.1. Nuclear radii estimates
  • 4.2. Fractional active area
  • 4.3. measurements
  • 4.4. Dust colours
• 5. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: September 2, 1999
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