Comet Section Observing Guide 1 The British Astronomical Association Comet Section www.britastro.org/comet BAA Comet Section Observing Guide Front cover image: C/2020 F3 (NEOWISE) by Peter Carson on 2020 July 12.. Back cover image: C/2011 W3 (Lovejoy) by Lester Barnes on 2011 December 23. © The British Astronomical Association 2020 2020 November (rev 6) 2 CONTENTS 1 Foreword .................................................................................................................................. 6 2 An introduction to comets ......................................................................................................... 7 2.1 Anatomy and origins ............................................................................................................................ 7 2.2 Naming .............................................................................................................................................. 12 2.3 Comet orbits ...................................................................................................................................... 13 2.4 Orbit evolution .................................................................................................................................... 15 2.5 Magnitudes ........................................................................................................................................ 18 3 Basic visual observation ......................................................................................................... 19 3.1 Sources of information ....................................................................................................................... 19 3.2 Finder charts ...................................................................................................................................... 19 3.3 Star hopping ...................................................................................................................................... 19 3.4 Instruments ........................................................................................................................................ 20 3.5 Other equipment ................................................................................................................................ 21 3.6 Visual observation ............................................................................................................................. 21 3.7 Estimating the magnitude .................................................................................................................. 23 3.8 Estimating the coma diameter ........................................................................................................... 24 3.9 Submitting observations .................................................................................................................... 25 4 Advanced visual observation .................................................................................................. 26 4.1 Telescope magnification .................................................................................................................... 26 4.2 Magnitude estimate ........................................................................................................................... 26 4.3 Star Magnitude sources ..................................................................................................................... 27 4.4 Coma Diameter .................................................................................................................................. 30 4.5 Degree of condensation .................................................................................................................... 31 4.6 Features in the coma ......................................................................................................................... 33 4.7 Tails ................................................................................................................................................... 34 4.8 Drawing comets ................................................................................................................................. 35 4.9 How to improve your observations .................................................................................................... 36 4.10 Very bright comets ............................................................................................................................. 37 4.11 Electronic submission of visual observations .................................................................................... 38 5 Imaging comets ...................................................................................................................... 39 5.1 Cameras ............................................................................................................................................ 39 5.2 Wide-field imaging ............................................................................................................................. 40 5.3 Remote observing .............................................................................................................................. 42 6 Processing your images ......................................................................................................... 45 6.1 Image calibration ............................................................................................................................... 45 6.2 Image stacking ................................................................................................................................... 46 6.3 Image processing .............................................................................................................................. 47 6.4 Sky Gradient removal ........................................................................................................................ 48 3 6.5 Other processing tools ....................................................................................................................... 48 6.6 Submitting images to the section archive .......................................................................................... 48 7 Extracting scientific data from images ..................................................................................... 53 7.1 Astrometry ......................................................................................................................................... 53 7.2 Getting an MPC code ........................................................................................................................ 56 7.3 Photometry ........................................................................................................................................ 57 7.4 Monitoring dust production ................................................................................................................ 64 7.5 Spectroscopy ..................................................................................................................................... 65 7.6 Monitoring 29P/Schwassmann-Wachmann ...................................................................................... 66 7.6.1 Background ..................................................................................................... 66 7.6.2 How to observe comet 29P .............................................................................. 67 7.6.3 Stacking individual frames ............................................................................... 68 7.6.4 Performing photometry .................................................................................... 69 7.6.5 Reporting photometry of 29P ........................................................................... 72 8 Observation reporting procedures .......................................................................................... 74 8.1 Visual observation report form ........................................................................................................... 74 8.2 Visual observation observing blank ................................................................................................... 76 9 Resources .............................................................................................................................. 78 9.1 Online ................................................................................................................................................ 78 9.2 Periodicals ......................................................................................................................................... 78 9.3 Books and atlases ............................................................................................................................. 78 4 Contacts Section website: www.britastro.org/comet BAA comets discussion email list: http://lists.britastro.org/mailman/listinfo/comets-disc Director: Nick James, 11 Tavistock Road, Chelmsford, Essex, CM1 6JL, England. E-mail: [email protected] Visual observations and analysis: Jonathan Shanklin, 11 City Road, Cambridge, CB1 1DP, England. E-Mail: [email protected] Section Secretary: Denis Buczynski, Templecroft, Tarbatness Road, Portmahomack, Near Tain, Ross-Shire, IV20 1RD, Scotland. E-mail: [email protected] Editor of The Astronomer magazine: Guy Hurst, 16 Westminster Close, Kempshott Rise, BASINGSTOKE, Hampshire. RG22 4PP, England.