Data Set Overview
=================
This data set presents data for the sizes, shapes, albedos, and colors
for comets collected from various sources in the literature. In some
cases, the authors have culled the data from published or well-known
unpublished sources, and have indicated what they judge to be the most
reliable value available.

Sizes, shapes, colors and albedos of comet nuclei culled from the
literature as presented in the following papers:

    Belton et al. (2004)
    Boehnhardt et al. (2008)
    Hsieh et al. (2009)
    Kelley et al. (2009)
    Knight et al. (2010)
    Lamy et al. (2004, 2008,2009, 2010)
    Lowry and Fitzsimmons (2005)
    Lowry and Weissman (2007)
    Snodgrass et al. (2005, 2006, 2008, 2010)
    Stansberry et al. (2004)
    Tubiana et al. (2008)


Parameters
==========
Measurements of effective radius, axial ratio and period are presented
for 164 comets and 35 asteroidal objects suspected of being dormant or
extinct comet nuclei.  Additional tables present colors, albedos, and
dimensions of nuclei.

In most cases of shapes determined from light curves (all but the 4
space mission targets), the values of one axis or another are limits.
In particular, generally one measures a lower limit to the ratio a/b
(and usually assumes c=b unless there are observations at many
different phases), plus a product of a and b. This pretty much means a
lower limit on a and an upper limit on b.


Processing
==========
These data have been keyed in to flat ASCII tables from the published
paper.  The format has been modified slightly to accommodate PDS
standards, usual SBN practices, and the preferences of users as
expressed by the external reviewers.


Modification History
===================
The PDS4 version of these data have been migrated from the following
PDS3-format data set:

  EAR-C-COMPIL-5-COMET-NUC-PROPERTIES-V2.0


Confidence Level Overview
=========================
The papers whose data have been included in this dataset contain
extensive remarks regarding the various observations and measurements
included in these tables.  While the tables present an excellent summary
of the state of knowledge, the user is strongly encouraged to consult
the published paper for the various caveats and notations included in
the remarks.


References
==========
Belton M.J.S., K.J. Meech, M.F. A'Hearn, O. Groussin, L. McFadden,
  C. Lisse, Y.R. Fernandez, J. Pittichova, H. Hsieh J. Kissel, K. Klaasen,
  P. Lamy, D. Prialnik, J. Sunshine, P. Thomas and I. Toth, Deep Impact:
  Working Properties for the Target Nucleus Comet 9P/Tempel 1, Space Sci.
  Rev., 117, 137-160, 2005.
Boehnhardt H., G.P. Tozzi, S. Bagnulo, K. Muinonen, A. Nathues and
  L. Kolokolova, Photometry and polarimetry of the nucleus of comet
  2P/Encke, Astron. Astrophys., 489, 1337-1343, 2008.
Hsieh H.H., D. Jewitt and M. Ishiguro, Physical properties of main-belt
  comet P/2005 U1 (READ), Astron. J., 137,157-168, 2009.
Kelley M.S., D.H. Wooden, C. Tubiana, H. Boehnhardt, C.E. Woodward and
  D.E. Harker, Spitzer observations of comet 67P/Churyumov-Gerasimenko at
  5.5-4.3 AU from the sun, Astron. J., 137, 4633-4642, 2009.
Knight M.M., M.F. A'Hearn, D.A. Biesecker, G. Faury, D.P. Hamilton,
  P. Lamy and A. Llebaria, Photometric Study of the Kreutz Comets Observed
  by SOHO from 1996 to 2005, Astron. J., 139, 926-949, 2010.|
Lamy P.L., I. Toth, Y.R. Fernandez and H.A. Weaver (2004), The Sizes,
  Shapes, Albedos, and Colors of Cometary Nuclei, in 'Comets II', edited
  by M.C. Festou et al., pp. 223-264, University of Arizona Press, Tucson,
  in collaboration with the Lunar and Planetary Institute, Houston.
Lamy P.L., I. Toth, O. Groussin, L. Jorda, M.S. Kelley and J.A.
  Stansberry, Spitzer Space Telescope observations of the nucleus of comet
  67P/Churyumov-Gerasimenko, Astron. Astrophys., 489, 777-785, 2008.
Lamy P.L., I. Toth, H.A. Weaver, M.F. A'Hearn and L. Jorda, Properties of
  the nuclei and comae of 13 ecliptic comets from Hubble Space Telescope
  snapshot observations, Astron. Astrophys., 508, 1045-1056, 2009.
Lamy P.L., I. Toth, H.A. Weaver, M.F. A'Hearn and L. Jorda, Properties of
  the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope
  multi-orbit observations, Mon. Not. R. Astron. Soc., 1-21, 2010.
Lowry S.C. and A. Fitzsimmons, William Herschel Telescope observations of
  distant comets, Mon. Not. R. Astron. Soc., 358, 641-650, 2005.
Lowry S.C. and P.R. Weissman, Rotation and color properties of the nucleus
  of Comet 2P/Encke, Icarus, 188, 212-223, 2007.
Snodgrass C., A. Fitzsimmons and S.C. Lowry, The nuclei of comets
  7P/Pons-Winnecke, 14P/Wolf and 92P/Sanguin, Astron. Astrophys., 444,
  287-295, 2005.
Snodgrass C., S.C. Lowry and A. Fitzsimmons, Photometry of cometary
  nuclei: Rotation rates, colours and a comparison with Kuiper Belt Objects,
  Mon. Not. R. Astron. Soc., 373, 1590-1602, 2006.
Snodgrass C., S.C. Lowry and A. Fitzsimmons, Optical observations of 23
  distant Jupiter Family Comets, including 36P/Whipple at multiple phase
  angles, Mon. Not. R. Astron. Soc., 385, Iss.2, 737-756, 2008.
Snodgrass C., K. Meech and O. Hainaut, The nucleus of 103P/Hartley 2,
  target of the EPOXI mission, Astron. Astrophys., 516, 2010.
Stansberry J.A., J. Van Cleve, W.T. Reach, D.P. Cruikshank, J.P. Emery,
  Y.R. Fernandez, V.S. Meadows, K.Y.L. Su, K. Misselt, G.H. Rieke, E.T.
  Young, M.W. Werner, C.W. Engelbracht, K.D. Gordon, D.C. Hines, D.M. Kelly,
  J.E. Morrison and J. Muzerolle, Spitzer Observations of the Dust coma and
  Nucleus of 29P/Schwassmann-Wachmann 1, Astron. J. Supp. Ser., 154,
  463-468, 2004.
Tubiana C., L. Barrera, M. Drahus and H. Boehnhardt, Comet
  67P/Churyumov-Gerasimenko at a large heliocentric distance, Astron.
  Astrophys., 490, 377-386, 2008.