Dear Amar,
http://www.planetarypositions.com/notes/2006/02/10/bhava-chart-chalit-chart/
How is Rashi Chart different from Chalit Chart?
1. Mathematically: Rashi chart assumes that all the houses are equal - 30 degrees in length. While calculating the positions of ascendant and other planets, we just take the modulo of the degree by 30 and assign the houses. In bhava chart, the mid point of a house, i.e. the bhava madhya, is given a lot of importance. The influence of a house is calculated based on this bhava madhya. e.g. if Ascendant value is 2 degrees, then the influence of the first house extends from approximately 350 degrees to about 17 degrees and not Zero to 30 degrees as would be the case with a rashi chart. The upper and the lower limits of influence of a house are called Bhava Sandhis. Planets are placed in this newly computed Bhava chart - and we get something called Chalit chart. The rule is simple, if a planet’s longitude is more than the starting sandhi and less than the end sandhi, it is said to fall in that bhava.
2. For interpretations: The combinations that are used for interpretations are - rashi chart along with divisional charts on one hand and bhava charts on other hand. We never mix divisional charts with bhava chart. Planets influence a chart based on the bhava they are situated in. Rule of thumb - if an interpretation system works only with planets and houses and not signs, you can safely assume that it is working with the chalit chart and not the rashi chart. However, the aspects of planets on other planets are always studied from rashi chart. Similarly exaltation/debilitation of planets is again studied only from the rashi chart. Manglik Dosha is studied partly from bhava chart (e.g. statements like Mars causes dosha if situated in 7th house) and partly from rashi chart. When looking for exceptions (e.g. Mars in Simha, i.e. in the sign of a friend does not cause dosha), we should see the rashi chart. Normally, bhava chart and rashi chart would agree with each other. However, if the Ascendant or planets’ degree is closer to multiple of 30, there may be differences between the charts. It is always interesting to see if a planet has moved from one house to another from rashi chart to chalit chart. This explains a lot of times why a yoga that is so obvious in rashi chart does not fructify in real life.
Ravi