Hi there - to enable this method to work with circumpolar planets, the algorithm for calculating the diurnal and nocturnal semiarcs (which domitude calculations rely on) has been adapted. See help below.
From the Helpfile.
Circumpolar Planets
It is important to note that the method has to be adapted for planets and points that are circumpolar at very high latitudes (north or south). Around or beyond the arctic and antarctic circles, planets and points may become circumpolar - that is, they don't rise or set during their diurnal cycle.
This means that the standard algorithm for determining the domitude of the planet or point, which relies on being able to identify the diurnal and nocturnal semiarc of the position, cannot be solved. The diurnal semiarc is the time taken for a planet to rise from the horizon to MC, and the nocturnal semiarc is the time taken for the planet to rise from the IC to horizon.
If a planet or point does not cross the horizon (never rises or sets) during its diurnal cycle, this arc cannot be calculated.
In this case, the diurnal and nocturnal semiarcs are assumed to be half the time taken for the planet or point to move from the IC to the MC, or to complete 25% of its diurnal cycle. This is always very nearly 6 hours, irrespective of the latitude or declination of the planet. Effectively, this means for circumpolar planets or points the 24 hour day is divided into two 12 hour timespans. This semidiurnal cycle is then divided in two again, to create two 1/4 day spans of 6 hours each. One 1/4 day is then allocated to the diurnal semiarc, and the other to the nocturnal semiarc.
Circumpolar planets are identified with 'cp' in the listings, aspect grid, and wheel.
Cast charts as follows to see this adapted method in action:
21 June 2021
11AM
Murmansk, Russia
22 December 2021
11AM
Murmansk, Russia
Other Notes
The orb is set at a standard six degrees for all aspects. Users may choose to display Ptolemaic aspects only. Please select the relevant option from the Display Options menu.
Users may also choose to show positions in the wheel in 360 degree notation.
For more information, see:
https://jcremers.com/forum/index.php/topic,37.0.htmlFor a critical appraisal of the method see:
http://www.astralis.it/pguinard_e.htm