**Personal
Sensitive Points in the Horoscope**

**Introduction **

**All astrologers
are familiar with the Ascendant and Midheaven in a horoscope, and many will have
come across the Vertex.**

**The Ascendant is
the point on the Ecliptic where the Ecliptic intersects the Horizon to the East
of the Meridian, while the Midheaven is the point where the Ecliptic intersects
the Meridian above the horizon. In polar latitudes, parts of the Ecliptic
will never rise, while other parts of the Ecliptic will never set. In
these cases, the Midheaven can be defined as being the intersection towards the
South (within the Arctic Circle) and the intersection towards the North (within
the Antarctic Circle), even if the Midheaven is below the horizon - that is as
high as that degree of the Ecliptic is going to get!**

**The Vertex is the
point where the Ecliptic intersects the Prime Vertical, (a Great Circle passing
directly overhead from due East to due West, and thence through the
Nadir). By definition the Vertex lies to the West of the Meridian,
and may be above or below the Horizon. The Vertex can be calculated by
finding the Ascendant at your Co-Latitude, (i.e. the Ascendant at 90 degrees
minus your Latitude, in the same hemisphere), at Sidereal Time 12 Hours later.**

**There are other
so-called Personal Sensitive Points, (PSPs), which include the Co-Ascendant,
(the Ascendant at your Co-Latitude, at the same longitude), the Equatorial
Ascendant, (the Ascendant at the Equator at the same Longitude), and the Polar
Ascendant, (the Ascendant at your Latitude at Sidereal Time 12 Hours later).**

**The eight PSPs
are completed by throwing in the 0 degrees Aries Point and (for some reason) the
Moon's Node.**

**If this seems
rather arbitrary and complicated, let us try to simplify things. Of the 8
PSPs, the Moon's Node is the odd one out. While it is no doubt important,
it does not fit into the same category as the other 7 PSPs which have something in common.**

**Why the 12 hours?**

**Why do we need to
add 12 hours of Sidereal time to calculate the Vertex and the Polar Ascendant,
(sometimes more sensibly called the Covertex). I believe the answer may
lie in that in the days before easy computation was available, Tables of Houses
were generally only available for Northern Latitudes. Calculations for
Southern Latitudes were performed by calculating the House Cusps for the
antipodean point in the Northern hemisphere, and switching the signs on opposite
cusps. This involved adding 12 Hours to the Sidereal Time. It seemed
more logical to me, when I started looking at the Vertex to calculate the
opposite point in the East, the Antivertex, and this involved subtracting 90
degrees from a North Latitude to give the Co-Latitude in the Southern
Hemisphere, at the same Longitude as the birthplace. A similar argument
holds for the Covertex and Anticovertex.**

**One Meridian**

**Calculating these
PSPs in this fashion ****involves
a simple progression down one line of Longitude, the Meridian. Near the
Poles, the Ascendant is always very close to 0 Aries or 0 Libra, since most of
the Ecliptic cannot rise or set there. At the North Pole, 0 Libra rises by
convention, though arbitrarily near the Pole, the last fraction of Virgo rises,
followed by the first fraction of Libra, followed by a flip to the first
fraction of Aries and the last fraction of Pisces, and a flip back to
Virgo. The Aries-Pisces portion is retrograde when rising! The
Poles are therefore firmly associated with 0 Aries and 0 Libra rising.**

**Moving South from
the North Pole, the Birth Latitude comes next, (giving rise to the Ascendant),
for Latitudes greater than 45 degrees North, then the Co-Latitude, (giving rise
to the Co-Ascendant). For Birth Latitude less than 45 degree North, it is
the other way round. Next comes the Equator, and the Equatorial Ascendant,
followed by the Antivertex and Anticovertex, (in either order, as above).**

**Another House
System?**

**Well yes and
no. Since 6 PSPs (and their 6 opposite points) lie on one Great Circle,
involving the Longitude line of birth, and the Longitude line 180 degrees away,
it is possible to construct a chart with the Ecliptic projected onto this Great
Circle, complete with House Cusps. The idea is not new, but it receives
very little attention. The East Point House System uses such a
projection. The house cusps divide space into 12 equal lunes, with cusp
lines all intersecting at the horizon points at due East and due West. The
chart is usually highly distorted, with houses of very unequal size, (as far as
the Ecliptic is concerned). Vertex lovers will be delighted that the
Antivertex or Vertex always falls at cusp 10 in the East Point System, according
to whether the Vertex or Antivertex is above the Horizon.**

**So the East Point
system is not new, but it does lead to an idea that is new, or at least I have
not come across it previously. Since the East Point System is unfamiliar,
and not for the faint-hearted, I shall demonstrate the idea for the Campanus
system.**

**Campanus
Revisited**

**Campanus
is one of the more popular House Systems where space is divided equally.
The Prime Vertical is divided equally into 12 sections, and great Semicircles
are drawn from due North to due South cutting the Prime vertical half way along
their paths. Thus the First House Cusp scuttles right along the Eastern
Horizon, while the Seventh Cusp completes the circle along the whole of the
Western Horizon.**

**It is possible to
project the positions of the planets onto the Prime Vertical. Since
planets do not necessarily lie on the Ecliptic, a planet near a House Cusp may
turn out to be in a different house. A table can be calculated showing
exactly how many degrees into a house a planet is placed. All Houses are
30 degrees in length along the Prime Vertical, though this is not the case along
the Ecliptic, (except in a couple of very rare instances).**

**A chart can then
be drawn showing the planets in their correct degrees of the houses.
Aspects can even be used, (e.g. a trine from 10 degrees in the Third House to 10
degrees in the Seventh). These will not be Ecliptic aspects, but aspects
along the Prime Vertical. So far so good.**

**Now comes the
difficulty. It would be nice to have signs in this Prime Vertical
Chart. After all, horoscopes are supposed to have signs and houses are
they not? So how to arrange the signs? With 360 degrees of Prime
Vertical circle there must be a way. What most people would do is to cram
the signs into the houses, with some houses being larger than others, (measured
along the Ecliptic). Is there a way of having equal Campanus Houses and
equal signs?**

**A clue comes from
looking at another system, based on the Celestial Equator. Here
astronomers use Right Ascension (RA) and Declination as their
measures. It is quite possible to equate the first thirty degrees of RA
(measured along the Equator) with Aries, the next 30 degrees with Taurus and so
on. Indeed some Ephemerides give positions in both Ecliptic Longitude and
Latitude, along with RA, (using signs along the Equator) and Declination.
A planet can be, for example, in 1 degree Taurus along the Ecliptic, and in 29
degrees Aries along the Equator. Aspects can form along the Equator, that
are not present along the Ecliptic, and vice versa.**

**So how to
proceed? The crossing points for the Ecliptic and the Equator are at 0
Aries and Libra, so obviously a planet or point at 0 Aries (with no
Latitude/Declination) will be at 0 Aries in both systems.**

**The points of
intersection of the Prime Vertical and the Ecliptic occur at the Antivertex and
the Vertex. So a planet or point on both the Ecliptic and the Prime
Vertical will have the same position in each system, or at least it would be
very odd if it did not!**

**So, for example,
if the Antivertex is in 15 Taurus, at an altitude of 20 degrees in the East, the
Ascendant, (along the Prime Vertical) will be 20 degrees after 15 Taurus, or at
5 Gemini. Cusp 10 will be at 5 Pisces. A planet anywhere on the
upper meridian will have position 5 Pisces, whatever its Ecliptic
position. A planet half way through the eleventh house will be at 20
degrees Aries in the Prime Vertical Chart.**

**All we have done
is to perform a coordinate transformation, in line with simple rules, but there
is a question as to whether the technique has any validity. Can a Prime
Vertical chart be interpreted? If so, can we have more than one
horoscope? In my opinion the short answer is yes, provided you do not mix
systems. The Equal House System, an Ecliptic-based method of house
division., responds well to transits and progressions. The Prime Vertical
chart also responds well to transits and progressions, even though these may
occur years earlier or later than the Ecliptic ones in the case of the outer
planets. You do however have to remember to convert progressed or
transiting Ecliptic positions to the appropriate Prime Vertical positions in the
natal chart!**

**For what it is
worth, my experience suggests that the Prime Vertical chart, where the signs are
added based on the position of the Vertex and Antivertex, adds an extra
dimension to chart interpretation. The Equal House method seems to relate
more to psychological events, while the Prime Vertical chart seems to relate
more to events. Long live the Vertex! Maybe Personal Sensitive
Points can lead to personal sensitive charts :-)**

**The same
technique can be used for some other house division methods, such as the East
Point and the Zenith system, though I have not investigated these extensively.**

**Relevant Links**

**The
Personal Points and how to calculate them**

**Personal
Sensitive Points and how they might be interpreted**

**Swiss
Ephemeris One of the best sites for astro software.**

**Page created 14th April 2001**

**Thank you for visiting.**