I wrote earlier to newsgroup about this problem. It seems to be
clear now.

Look situation where we placed in Polar Zone in summer in midnight
(or in winter in midday - result is same). Outside Polar Zone all
is OK. If we increase latitude, we will find point, where Zenit-Nadir
line is parallel to Ecliptic axis, that mean, local horizon match
Ecliptic. If we increase latitude more, then MC, calculated by
latitude-idependent formula, goes under local horizon. So I thought,
that MC must be flipped in this case.

I looked, how are calculated house cusps in this case in Astrolog 5.20
and some other programs. Astrolog doesn't flips anything and for
example Porphyry house cusps are mixed. "Astroloy for Windows"
demoversion 2.2d by Halloran Software flips MC, but it reverses also
direction of houses on Zodiac: with increasing of house numbers
zodiacal coordinates of house cusps decreases. I wasn't sure, which
result is true and sent short message to alt.astrology to clarify
situation.

John Halloran sent me letter, where draw my attention to point, that
in this situation Ascendent is flipped - point on zodiac, which was
ascending on lower latitudes, is now descending.

In Astrolog 5.20f I changed calculations of house cusps in Polar Zone.
In situations described above MC-IC and ASC-DES was reverted, also
houses order on zodiac (depending of house system). In other words,
Astrolog 5.20f gives in such situations same result, than Halloran's
"Astrology".

After posting to alt.astrology about changes in Astrolog5.20f,
I received letter from Jonathan C. Dunn, where he wrote, that Polar
Zone MC is same as normal latitudes. Reason - definition of MC:
MC and IC are defined as points, formed by an intersection between
Ecliptic and meridian. (quotation from letter follows):

: 1) Which point of ecliptic is highest relative to horizon?
: 2) Which point of ecliptic is at ITS OWN highest point relative
: to horizon?
:
: #1, above, is not the MC, it is the zenith/birthplace, also
: called the nonegesimal, the point always square to the ASC.
: No conceptualization of motion is required to conceptualize
: or understand it. You just run a line from the zenith down to
: the nearest point on the ecliptic.
:
: #2, above, is the MC. It is seldom square the ASC, and requires
: a calculation or conceptualization of daily motion of ecliptic
: points. The daily motion of each ecliptic point is an a small
: circle parallel to the equator. It turns out that to find the MC,
: you run a line from the zenith toward the nearest point on the
: equator. Whatever point on the ecliptic that this line passes
: through it the MC. A more complex notion.


So I found three points of view:

1. Original Astrolog calculations, where MC and (or) Asc aren't flipped.
Seems there named problem isn't taked into account at all.

2. Point of view of Halloran's Software. Flipped are both MC and Asc, and
houses order on Zodiac is reversed too.

3. Point of view of Jonathan C. Dunn. Flipped is only Asc. MC in Polar
Zone is same, as at normal latitudes.


Discussion with Mr. Dunn cleared situation. If we use second definition
(which is correct definition of MC), MC is same independent of latitude
and DOESN'T flip in situations like above, but Ascendent flips. As result
houses order on Zodiac isn't reverted.

So I have made more changes in Astrolog 5.20f than necessary. Enough to
flip only Ascndent in situations described above. In near future I hope
to finish with version 5.20g where this problem will be solved.


Valentin Abramov valja@tartu.customs.ee
http://b2400z.customs.ee/valja.html



I finished changes in Astrolog 5.20g and sent corresponding message to alt.astrology. After this I received first reply to my posting about houses in polar zone. Here it is quoted.


Date sent: Fri, 16 Aug 1996 19:30:36 -0700 (MST)
To: valja@tartu.customs.ee
From: seagoat@primenet.com (John A. Halloran)
Subject: Re: MC in polar zone

Valentin et al.,

The grand master of modern astrology, Robert Hand, has already
thoroughly explored this subject of the ascendant, midheaven, and
vertex at extreme latitudes.

There are two ways to define and determine the ascending or descending
nodes of intersection between the great circle planes of the ecliptic
and the horizon and meridian circle.

I quote from Essays on Astrology, copyright 1982 Robert Hand.

"1. The Ascendant

"A. According to Direction: The intersection of the ecliptic and
rational horizon in the east, i.e., the eastern node.
"B. According to Up and Down: The ascending node of the ecliptic
upon the rational horizon.

"2. The Midheaven

"A. According to Direction: The intersection of the meridian circle
and the ecliptic in the south. This is expressed by the old
English term "southing," used for upper meridian passes.
"B. According to Up and Down: The intersection of the meridian circle
and the ecliptic that is above the horizon, as opposed to the one
below the horizon, which in normal latitudes is the Imum Coeli
(I.C.)."

The important point is that one be consistent in defining both the
Ascendant and Midheaven either according to Direction or according
to Up and Down. One should not mix them.

You should obtain and read Hand's book yourself. He concludes a
lengthy discussion by saying, "I always favor making the Ascendant
the ascending node of the ecliptic upon the horizon, and
concurrently making the Midheaven the ecliptic-meridian intercept
above the horizon. This sometimes necessitates reversing some of
the other cusps, but these reversals do not violate the spirit of
the mathematical bases of any of these systems."

Robert Hand's conclusion is consistent with the practice of Swedish
astrologers and with the behavior of AstrolDeluxe for Windows and
Astrology for Windows.

source: http://astrolog.offline.ee/astrolog/changed/polar.html