The Kracht Group Pair C/2000 O3 = 2005 W4

This orbital linkage was published on MPEC 2005-X14.

My measurements of C/2000 O3 (black dots) and C/2005 W4 (blue dots) corrected for phase angle and distance.
While C/2000 O3 passed behind the sun, C/2005 W4 passed in front of it resulting in magnitude corrections of
mag 1.6 to 1.2 for the first three (blue) data points.

Without the corrections for phase angles the light curves look more similar:

Assuming that both comets are identical, the light curves indicate that the dust-to-gas ratio is much smaller than
that for the Kreutz group comets resulting in much smaller corrections for phase angles.
M. Knight has mentioned the possibility that the Marsden and Kracht comets are extremely gassy or or have
very small dust particles in his thesis (footnote to C/1999 J6 in appendix C).

The next perihelion is expected for 2011 March 10, but probably too faint for the STEREO SECCHI coronagraphs.
Perhaps SOHO LASCO is still working at that date.