Progression Day Type

When charts are progressed by secondary or tertiary rate, it is possible to base the progression rate on either a solar day or a sidereal cycle. (Minor progressions are not based on days, so are not affected by this option). The solar day is the time taken for the sun to move from the Midheaven on one day to the Midheaven on the next day - that is 24hrs. This is the standard rate, also known as Q2. This is the rate that is in most common use by western astrologers. The sidereal cycle is the time taken for a fixed star to move through 24hrs of arc, which is slightly more than 24hrs of clock time. This is the Bija rate, also known as Q1. Astrologers who use the sidereal zodiac sometimes use this rate. The ratio of the standard rate to the Bija rate is 0.997269566.

When you change this option in the "Preferences" dialog, "Progs/Dirns" tab, any progressed charts or dynamic reports involving progressions that are subsequently calculated will use the newly selected progression day type. It is possible to determine which progression day type has been used in a progressed chart by checking whether the chart type in the chart details text - this includes either Q1 or Q2 in its name. Similarly, it is possible to determine which rate was used in a dynamic report by looking at the list of selected events in the report header. This contains a description of the progression type, method and rate.