Who makes a panchang?
A panchang is published by many makers across India, and they follow different traditions, ayanamsas and sunrise conventions. The same date can have slightly different values in different panchangs.
What it is
Makers choose an ayanamsa, a sunrise method and a set of rules for the tithi and nakshatra end times. The differences are usually small, but they can change the day on which a festival falls.
How it is worked out or read
When comparing a joshiastro result with a printed panchang, check the ayanamsa, the city and the sunrise convention. The site's method is on the method page, and the verification plan compares results against published panchangs.
Where it appears on this site
The method is on the method page. The verification article describes the comparison.
Who makes panchangs
Panchangs have traditionally been prepared by families of astronomer-astrologers, often over many generations, and published for a region or a community. Each tradition has its own conventions: its year beginning, whether months run amanta or purnimanta, its festival rules, and the astronomical method it follows. Today, alongside these traditional publishers, there are government publications such as the Rashtriya Panchang, wall calendars printed by commercial publishers, and a large number of websites and apps.
Drik and older methods
An important distinction among panchang makers is the method of calculation. Drik panchangs use positions from modern astronomy, so their tithi and nakshatra times match what is actually observed. Some traditional panchangs follow older methods, either the parameters of the Surya Siddhanta or, in parts of South India, the vakya system, which uses memorised tables of values. These can differ from drik values by minutes or, in some cases, more. In Tamil Nadu, for example, both vakya and drik almanacs are published, and festivals are sometimes kept on different days by their followers.
The editor's judgement
Beyond calculation, a panchang maker must decide how to apply festival rules in difficult cases. When a tithi spans two sunrises, or ends just after sunrise, or when a festival depends on the tithi at a particular time of day such as midnight or noon, the rules of the tradition must be applied with care. Experienced editors resolve such cases according to their tradition's texts, and their decisions are why families trust a particular almanac.
Software and websites
Software can compute positions precisely, but it does not by itself know a community's festival rules. A good digital panchang states its location, ayanamsa, sunrise convention and festival rules, so that users know what it assumes. Where a website gives a festival date that differs from the family almanac, the difference usually lies in these rules rather than in the astronomy.
Choosing an almanac
For family observances, the almanac followed by one's community or temple is usually the most useful reference, since it keeps everyone on the same date. For exact local times, such as Rahu Kaal or the end of a tithi in a particular city, a drik calculation for that city is more precise. Many families use both, and this site's panchang is designed to complement a family almanac rather than replace it.