Clairvision Virtual Astrologer offers methods of calculating progressions:
Each of these can be calculated for direct progressions and converse progressions (see Converse Progressions below).
In case of doubt, and if you are not keen on technicalities, simply choose True Solar Arc in longitude (the one on top of the list, as always in Clairvision Virtual Astrologer).
Now for the explanations (which you need to read only if you wish to understand how it all works).
To calculate the progressed chart one uses the same time and place as in the natal chart, but one adds one day per year. Thus, to calculate the progressed chart for someone's 26th year, one simply adds twenty five days to the date of the natal chart. Thus the birth chart and the progression for the first year are identical.
As we saw in an earlier section we could call this 'plain vanilla progression', and it's not the most often used. Traditionally, even though the planets of a progressed chart are calculated in this way, the angles are calculated ('progressed') differently.
Notice that in all the following variations, the positions of the progressed planets are identical to those of the 'plain vanilla progression' progressed chart. What varies is the method of progressing the angles.
Among the methods of progression, True Solar Arc in longitude is the most commonly used by astrologers.
Having progressed the Sun (as in the 'plain vanilla method') one calculates its distance from the natal Sun. This distance is then added to the natal Midheaven. This new Midheaven becomes the Midheaven of the progressed chart, and determines a sidereal time, using which the Ascendant and the houses of the progressed chart are calculated.
Instead of terrestrial longitude, True Solar Arc in Right Ascension uses its celestial equivalent: Right Ascension.
The difference between the natal Sun in RA, and the progressed Sun in RA is calculated and this value is added to the RA of the natal MC to give a new MC in Right Ascension. From there the positions of the Ascendant and other house cusps are calculated.
This is the second most often used variation (after the True Solar Arc in Longitude method).
The Naibod is a value related to sidereal time. It is worth 59'08' of arc.
To calculate this form of progression, one first calculates the planetary positions as in the 'plain vanilla method' described above, moving all planets forwards by one day per year. Then, to the sidereal time of the natal chart, one adds the value of the Naibod multiplied by the number of years (i.e. by 26, if doing the progression for the 26th birthday.)
Using this new sidereal time, one calculates the Midheaven, Ascendant, and other houses of the progressed chart.
This form of progression is less often used by astrologers than the ones we have just seen.
To calculate it, one first calculates the planetary positions as in the 'standard' progressed chart. Then, to the natal Midheaven one adds the value of the Naibod multiplied by the number of years (i.e. by 26, if doing the progression for the 26th birthday.)
This directed MC becomes the MC of the progressed chart, and determines a new sidereal time, from which the Ascendant and houses of the progressed chart are calculated.
Converse progressions can be found in the Prediction tools of Clairvision Virtual Astrologer, under 'Directions'.
Just as progressions for the 26th year are calculated by adding 25 days, so the converse progressions are calculated by subtracting 25 days.
We have included this prediction tool to give you a bit of variety and let you do your own research. From our point of view, converse progressions are a minor prediction tool. Unless someone comes up with some brilliant theory on how to interpret them, they are more a curiosity than anything real.
There is no specific function in Clairvision Virtual Astrologer for relocating progressions, however it can be done by editing the original chart with the new coordinates and then progressing it.
Relocating a progression means calculating it for a different location than that of birth. Suppose you were born in Los Angeles and now live in Buenos Aires. Relocating the progressed chart of your next birthday would mean calculating it for the longitude and latitude of Buenos Aires not that of Los Angeles.
Relocation makes a lot of sense for solar and lunar returns (see Relocating returns). But when it comes to progressions, the difference in the results is completely insignificant (except if you are specifically interested in the progressed Midheaven and Ascendant).
But even if you want a precise progressed Midheaven and Ascendant, it is disputable whether relocating a progressed chart makes any sense at all. For, unlike solar and lunar returns, progressions are calculated for a time which is close to the date of birth. For instance, the progression for your 30th birthday is the chart of the 30th day that followed your birth. At that time, resuming our example, it is quite likely that you were still in Los Angeles not in Buenos Aires. Thus the 'true' progressed chart is the one for Los Angeles, not Buenos Aires.
Following this line of thinking, relocating a progression would make sense only if the baby had been relocated (that is, if your parents had already moved to Buenos Aires by the time you were 30 days of age.)
Because progressions deal with movements as small as one degree per year, orbs of progressions are customarily smaller than for transits or natal aspects.
For more on orbs, refer to Aspect Orbs.