The calendar dates shown in the daily text of this Panchang are those of National Calendar, All-India Nirayana Solar Calendar, Gregorian calendar and Islamic Calendar. The calendar known as ‘National Calendar’ was introduced by the Govt. of India with effect from 22 March 1957, corresponding to the 1st day of the year of this calendar which was 1 Chaitra 1879 Saka Era. Thereafter, with effect from 14 April 2004 or from 25 Chaitra 1926 Saka Era of the National Calendar, Govt. of India introduced a uniform All-India Nirayana Solar Calendar corresponding to 1 Vaisakha, 5105 Kali Era, Kali Era being chosen as the era for this calendar. This Nirayana Calendar has fixed number of days for its month and consequently has leap years at required intervals. The intention for introducing this calendar has been that it would progressively replace the divergent regional Nirayana Solar Calendars and bring about uniformity in our traditional calendric system.

The length of the year of the National Calendar is that of the tropical year, and its Saka Era begins from the vernal equinox day of 78 A.D. The leap years of this calendar are determined by adding 78 years to its Saka Era years and then if the sum becomes divisible by 4 then that year will be a leap year. But when this sum becomes a multiple of 100, it would be a leap year only when it is divisible by 400, otherwise it would be a common year. This method has been adopted for the reason that leap years of the National Calendar occur in the same year period as that of Gregorian Calendar so as to maintain a permanent link between the dates of these two calendars.

The epoch of Kali Era adopted for All-India Nirayana Calendar is midnight (IST) of 17/18 February of 3102 B.C. or-3101 A.D. of Julian calendar and the length of its year is reckoned on the basis of true length of sidereal or nirayana year. For calendric purposes, the All-India Nirayana Calendar has been deemed to have started from 5101 Kali Era year. The methodology for determining leap year of this calendar is given below: If a Kali Era is divisible by 4 but not divisible by 4000, then that year is considered as a leap year. Accordingly Kali Era years like 5104, 5108, 5112.... etc. are leap years but 4000, 8000, 12000... etc, are not leap years. There are also additional leap years. If a Kali Era year becomes divisible by 150 then the subsequent year of that Kali Era year will be an additional leap year. Accordingly Kali Era years like 5101, 5251, 5401... etc. are additional leap years.

In the table below, the months of National and Nirayana Calendars, number of days assigned to each month of two calendars and the dates of Gregorian Calendar corresponding to the first day of each month of these two calendars have been detailed.

Timings of some elements in the panchang have been calculated for an adopted Central Station of India situated at 82° 30' Longitude East and 23°11' Latitude North (same as Latitude of Ujjain), and for other matters it has been done with respect to local meridians. The timings of different phenomena given in this panchang are in local mean time of the Central Station, which is the same as Indian Standard Time. This time (I.S.T.) is 5h 30m ahead of the Universal Time or Greenwich Mean Time. In general, this panchang may be used for all regions of the country.

In the beginning of each month’s daily panchang information, the data of the month of the National Calendar is provided along with the corresponding time period of the months of All-India Nirayana Calendar, kali aharganas, Julian days covering the month period of National Calendar as well as seasonal and astronomical information. In addition to five panchang elements, namely vaar, tithi, nakshatra, yoga, and karana, information is furnished for kali ahargana, Julian day, times of sunrise and sunset, and moonrise and moonset for an adopted Central Station of India , position of the moon in nirayana rasis, age of the moon corresponding to sunrise time for the adopted Central Station, declination of the sun, sidereal time (noon), equation of time, beginning of lagnas at four metropolitan cities at a time near to sunrise time at respective places, Midday times of these cities as well as Central station and all national festivals have been given for each day of the month of National Calendar. The symbols ● ☽ ○ ☾ indicate new moon, first quarter, full moon and last quarter respectively.

Tithi is the time period during which the moon gains 12 degrees or its integral multiples in longitude on the sun. The lunar months cover the period between ending moments of two successive new moons or ending moments of two successive full moons. Nakshatra is the time taken by the moon to traverse a segment of 13° 20’ or its integral multiples of nirayana zodiac. There are in all 27 nakshatras covering 360° along the zodiac. Yoga is calculated from the sum of the nirayana longitudes of the sun and moon. When this sum amounts to 13° 20' the first yoga ends, when it amounts to 26° 40’ the second yoga ends and so on. There are in all 27 yogas covering 360°. Karana is the time period during which the moon gains 6 degrees in longitude on the sun, and thus there are two karanas covering two half periods of tithimana. There are 7 karanas which repeat in a cyclic order starting from 2nd half of sukla pratipada and ending at 1st half of Krishna chaturdasi. There are 4 sthira or non-recurring karanas which cover the period from 2nd half of Krishna chaturdasi to 1st half of sukla pratipada. The full list of names of tithi, nakshatra, yoga, karana and rasi are given in the table on page xiv of the Rashtriya Panchang.

Kali ahargana is the number of days elapsed at 0h I.S.T. since midnight of 17/18th February, 3102 B.C. or -3101 A.D.,and Julian day is the number of days elapsed at 05h - 30m I.S.T. since the Greenwich noon of January 1, 4713 B.C. The time of sunrise and sunset and also of moonrise and moonset relate to the appearance and is appearance of their upper limbs on the horizon and these are in I.S.T. These timings against a particular station given in I.S.T. can be reduced to local mean time (LMT) by applying correction, on the basis of latitude and longitude of the station. Moon’s age is the number of mean solar days elapsed since the preceding new moon (conjunction) and here it has been reckoned at the moment of sunrise for the adopted Central Station on each day. Declination of a celestial object signifies its angular distance from the celestial equator and is measured along the perpendicular arc on the equator drawn through the object. It also indicates the position of the object on the celestial sphere north or south of the equator. The sidereal time is the measure of time defined by the diurnal apparent motion of the vernal equinox. Sidereal time (noon) is the hour angle of the vernal equinox at mean noon, i.e. it is the right ascension of the fictitious mean sun. The equation of time corresponds to 12h I.S.T. and has been defined as: 12h minus time of transit of mean sun over adopted central meridian and is applicable for the whole of India without much modification for the local noon. Depending on transit time, the equation of time may be positive as well as negative. Lagna timings shown against four metropolitan cities are the timings near to sunrise time when the point of ecliptic where 1st point of the mentioned rasi is located, will arise on, or touch the eastern horizon of the place. The midday or apparent noon is the middle of the day or the time when the sun is on the meridian of the place. The timings given are the mean times in I.S.T.

*The phenomena Sayana Vyatipata is defined when the sum of the tropical longitudes of the Sun and Moon equals 180° and Sayana Vaidhriti is when the above sum amounts to 360°.

In providing information on the timings of different phenomena, the sunrise system of reckoning the day has been followed in pursuance of the Indian convention. The day has been taken to begin for this purpose from the time of sunrise of an adopted Central Station. Tithis etc. which start after this time of sunrise and end before the time of next sunrise have been shown under that day. The timings of any phenomena that continue beyond 24h, that is, beyond midnight to the time of next sunrise which may happen at a time upto 30h or so, have been indicated as 25h, 26h etc., meaning 1AM, 2AM etc of the next day of the Gregorian calendar. If the day starts at midnight it is indicated as 24h or 0h and also where 12h means noon.

The text giving daily information of different astronomical phenomena, starts by giving the day of the week and is followed by the date of National Calendar, date of Nirayana Calendar- indicated by prefixing (ni), date of Gregorian Calendar and the date of Islamic Calendar. The dates of Islamic Calendar have been reckoned from the day following the first visibility of lunar crescent at the adopted Central Station. For those who wish to consult the Rashtriya Panchang to get information on calendric dates of various regional calendars, a table is provided in the beginning of the book giving the starting dates of months of different regional calendars.

For providing information about night sky for 12 months of the year, 12 number monthly star charts have been given in the text portion. Each chart corresponds to a particular Gregorian month. From a particular place, the stars corresponding to a particular month will be seen at 21h 30m, 20h 30m and 19h 30m of local mean time on the 1st, 16th and 30th of the month. The Star Chart meant for a particular day for a given hour can be used for the next day 4 minutes earlier and for the previous day 4 minutes later.

A graphical representation showing the movements of the sun and planets in nirayana rasis for the Gregorian year has been provided. From the graph, the timings of retrogression of the planets, conjunctions among the planets and that between the sun and planets, ingress of the planets into rasi segments, etc. can be assessed.

In the calculation of sunrise and sunset, atmospheric refraction is included and the times relate to the appearance and disappearance of the upper limb of the sun on the horizon. These times are in I.S.T. The amount of horizontal refraction taken for the purpose is 31’ and that of the sun’s semi-diameter is 16’ so that at the moment when the upper limb of the sun is visible on the horizon, the centre of the sun is actually 47’ below the horizon, the time equivalent of which is about 3.5 minutes.

The timings given against tithi, nakshatra, yoga and karana are their ending moments (i.e., when the span of the phenomena is completed). These moments having been given in I.S.T. and the phenomena being geocentric ones, the timings require no correction for other places, and are applicable for any place in the country in I.S.T. as given. These timings reduced by a deduction of 5h 30m would give the UT of the phenomena and is applicable for all places on the earth. When the ending moment of a tithi, nakshatra or yoga does not occur within the period from sunrise to next sunrise i.e., when it covers the whole day, the fact is indicated by the term “ahoratra”.

The tithis have been shown along with the names of the lunar month in which they fall. The lunar months have been reckoned from the day following the new moon and have been named after the nirayana solar month in which this initial new moon falls. For this purpose the solar months are reckoned to cover the period from exact time of ingress of the sun to the concerned rasi to the exact time of its transit to the next rasi. As such amanta or sukladi system (mukhya mana) of month reckoning has been followed

The calculations of nakshatras and yogas have been done on the basis of variable ayanamsa (also called increasing ayanamsa).The value of this ayanamsa has been shown in Panchang for the first day of each month. In the calculation of the beginning of the solar months like saura vaisakhadi etc., a fixed ayanamsa of 23°15 has been used. However, calculation of nakshatras is based on the nirayana system and hence they maintain a permanent relationship with the fixed stars. For the purpose of intercalation of lunar months with the solar months, the solar samkrantis have been computed according to nirayana system, while the saura months mentioned above are based on the sayana calculation and these conform to the present seasons for all time to come.

The transits of the sun and moon into nirayana rasis calculated on the basis of the variable ayanamsa (also called increasing ayanamsa) have been given in the body of the Panchang. Those of the sun and planets have been given separately at the end. The transits of the sun and planets into nakshatras, similarly calculated, have also been given separately. For the purpose of calculation of rasis and nakshatras, an initial point which occupies a fixed position on the ecliptic has been adopted as the origin for the measurement of longitudes. The position of this initial point coincides with that of vernal equinoctial point of vernal equinox day of 285 A.D. when ayanamsa was zero. However, for the purpose of assigning a precise position to this fixed point, the tropical longitude of this initial point has been adopted as 23° 15’ 00” for 0h on 21st March, 1956.

Times of sunrise and sunset and of moonrise and moonset for four metropolitan cities, the beginning of different lagnas of the Central Station for each day of the year along with a correction table for different places and also the nirayana longitudes of the sun, moon and planets have been given at the end. The adopted mean longitude of the planets for Chaitra 1 together with appropriate bija correction to surya-siddhanta elements yielding these mean longitudes have been given on the last page.

Tables showing the heliacal rising and setting of planets (udayasta) calculated for the Central Station of India, retrogression and direct motion of the planets (vakri and margi) and a table of eclipses that are visible and invisible from India and a chart of visibility of planets have also been given at the end.

Data for 13 months of national calendar, viz. from Chaitra of current Saka Era to Chaitra of next Saka Era have been given in this Panchang so that panchang information for 12 nirayana months from Vaisakha to Chaitra covering a complete nirayana calendar year is available. All calculations are based on accurate positions of the sun, moon and planets as given in the Indian Astronomical Ephemeris which is compiled after making use of the latest available corrections.

*The phenomena Sayana Vyatipata & Sayana Vaidhriti are calculated on the basis of defination given in the report of Calendar Reform Committee. These are classified as the Calendar Reform Committee view and no way related to the ‘Mahapata yoga’ defined in some Indian traditional texts (Siddhantic treatises).