As the panchang of the day is defined at the sunrise. The location plays a very important role. The latitude, longitude and the timezone of a place determine the time of the sunrise and sunset. For most of India the location of Ujjain can be considered as a crude approximation. For other countries the changes in panchang would be significant. The same principle used in India can be used to find panchang for any location on the earth.
Note: That exact moon phase and astronomical events and transitions would happen for all locations simultaneously. But the timezone and longitude differences ensure that time shown on clocks differ, also their positions in the sky may also differ.
Depending on the location and timezone of a place the sunrise and sunset of a place can be calculated. The sunrise is defined to take place when the upper edge of sun rises from the horizon, similarly for sunset is defined when the trailing edge of the sun's disk disappears. Atmospheric Refraction is also taken into account as at rise/set the actual position of sun is slightly different from apparent position.
But in Hindu Calendar the sunrise/sunset is taken to be the point when the middle of the disk of the sun crosses the horizon. The time difference due to this can be a couple of minutes. This affects the Jyotish, muhurtum calculations. This app implements the latter version, i.e, according to Hindu convention.
It is the amount of precession, or the longitudinal difference between the Tropical (Sayana) and Sidereal (Nirayana) zodiacs. Because of precession of earth (which causes the pole star to change too) there is inconsistency in the star charts used in the past and the present. To compensate, this quantity is added to longitudes to find values coherent with the past. The default in this application is Lahiri/ Chitrapaksha Ayanamsa. But you can choose Raman and Krishnamurti (Old) too from settings.
Rahu and Ketu were Asuras in Hindu Mythology responsible for eclipses of sun and moon. They do cause eclipse, but in reality they are not asuras. They are actually two points of intersection of the paths of the Sun and the Moon as they move around the celestial sphere. (Ascending and descending nodes on the lunar orbit). When the position of moon on Amavasya or Purnima falls near Rahu or Ketu's Position, we have an eclipse (partial or complete). They are imaginary, i.e, they have a position in sky but there is nothing present there.
Kundali is a pictorial representation of the position of the planets (Grahas) in the 12 rashis. In the northern style Kundali, the Lagna (Ascendant Rising Rashi) takes the centeral position. The rest are numbered in anti-clockwise order. In Southern type of Kundali the position of the rashis is fixed. The second one on the first row is Mesha(Aries). The others are numbered in clockwise order. The rashi of the Lagna is depicted as a cross line on its box.
Rahu Kalam, Yama Ghanta, Guli Kalam, Abhijit and Dur Muhurt are some of the 'kal' and 'muhurt'. The day from sunrise to sunset, and the night from sunset to the next sunrise, is divided into different divisions. And based on the day of the week and/or other factors, rules define their duration and time of occurance.
The daytime and night time is divided into 8 divisions each. Thus giving day and night choghadiya. These divisions are assigned any one of these names based on rules and are presented in a tabular form.
Similarly for Hora tables 12 divisions each are made for the day and night duration and are named after planets
Lagna is zodiac sign near the horizon at the point of sunrise.
Kundali Milan or Ashta Koota Milan is done by comparing the kundali of bride and groom on a 36 point scale. There are eight different criteria on which the calculation is done.