My guess is it refers to minor lunistice.
Caput Draconis is a medieval term for the ascending lunar node. A lunar node is the point of intersection between the ecliptic and the plane of the lunar orbit. The term translated is literally 'the dragon's head' and refers to the moon ascending from the South to the North....
The moon crosses the ecliptic twice every month and each crossing is called a node, but when people refer to the nodes, they generally mean the nodes that occur when the moon crosses the ecliptic as it crosses in front of the sun.
This happens twice each year, and a solar eclipse will be visible somewhere -often over the sea - about twice each year.
In this diagram the moon is on the ecliptic (the same path as the sun) as it crosses in front of the sun, it is also incidentally, the equinox because the sun is aligned with the celestial equator and the ecliptic.
This did not happen this year - on March 20th 2015 - the moon was descending. The next node occurs close to the autumn equinox and so Caput Draconis (the ascending node) is in Virgo this September.
The terms Major and Minor are somewhat confusing, as maximum and minimum moon rise and set positions occur around the years of lunistice -a year or two before or after - not just on the specific year. But to simplify, this is what happens at those times.
In years of Major lunar standstill there will be:
- Lowest midsummer solstice moon (low in the sky, minimum declination)
- Lowest autumn equinox moon.
- Highest midwinter moon.
- Highest Vernal equinox moon.
In years of minor lunistice -this year!
- Lowest winter solstice moon.
- Lowest vernal equinox moon.
- Highest midsummer moon.
- Highest autumn equinox moon