Nautapa 2027 and 2028 Dates: Sun in Rohini, Nine Days

Nautapa (नौतपा) is a count of days, not an astronomical event. The popular north Indian almanac reckoning reads the name as “nine heats” and takes the nine days that begin when the Sun enters Rohini nakshatra. The entry itself can be computed. By the site’s JPL DE421 ingress table, with the Lahiri ayanamsa, the Sun will reach Rohini at 21:39 IST on 25 May 2027 and at 03:48 IST on 25 May 2028. Where the nine days start depends on how a day is counted, and the two counts disagree in 2027 but not in 2028.

What the Entry Instant Is

The 27 nakshatras divide the sidereal zodiac into equal arcs of 13°20′. Rohini is the fourth, so it begins at 40° of sidereal longitude, which is 10° into Vrishabha (Taurus). The Sun reaches Vrishabha first: it will enter the sign on 15 May 2027 and, the next year, on 14 May 2028, ten or eleven days ahead of Rohini. The Rohini entry is the moment the Sun’s sidereal longitude reaches 40°.

The Sun then stays in Rohini for 13 days and 21 hours, until it crosses into Mrigashira, and the stay comes out the same to the hour in each of the three years. Nine days is well inside that stay: by either count, the ninth day ends with the Sun still in Rohini. In 2027 the ninth date of count (a), 2 June 2027, comes 6 days before the Mrigashira entry on 8 June 2027. The Sun in Rohini page lists the Sun’s spells in the nakshatra from 2026 to 2028 by date, with its four padas.

Nautapa 2027 and 2028: Two Ways to Count Nine Days

Count (a): the calendar day of the entry is day 1. The nine days are the entry date and the eight dates after it.

Count (b): the first sunrise after the entry opens day 1. A panchang day runs from one sunrise to the next, so on this count day 1 is the first panchang day that begins with the Sun already in Rohini, and day 9 lasts until the sunrise after the ninth date.

Sunrise and sunset below are for New Delhi, from the site’s sunrise formula.

2027. The entry at 21:39 comes after the 19:10 sunset, so the first sunrise in Rohini is the next morning’s. Count (a) gives 25 May to 2 June 2027; count (b) gives 26 May to 3 June 2027. An almanac that publishes Nautapa 2027 from 25 May and one that publishes it from 26 May can both be reading the same instant.

2028. The entry at 03:48 comes before the 05:25 sunrise, so both counts start on 25 May 2028 and end on 2 June 2028. Strictly, a 03:48 entry falls inside the panchang day that opens at sunrise on 24 May 2028, but neither count takes that day as day 1; the Sun will spend most of it in Krittika.

2026, for reference. The entry was at 15:34, in daylight, so the counts differed by a day: count (a) ran 25 May to 2 June 2026 and count (b) 26 May to 3 June 2026.

The choice of city does not change these answers. Across the 38 cities of the site’s city panchang, the latest sunset on 25 May 2027 is 19:28 in Jammu, still before the 2027 entry, and the earliest sunrise on 25 May 2028 is 04:32 in Guwahati, still after the 2028 one. So count (b) starts on the same date in every one of those cities in all three years.

How the Ayanamsa Can Move the Date

The clock times above are the instants at which the DE421 Sun, reduced by the Lahiri ayanamsa, reaches 40°. A different ayanamsa puts the start of the sidereal zodiac somewhere else and moves the instant with it. Near the end of May the Sun covers about 0.96° a day, so every 0.1° of difference in the ayanamsa moves the entry by about 2.5 hours; a larger ayanamsa makes it later, a smaller one earlier.

That is enough to move a date. The 2027 entry sits 2 hours 21 minutes before midnight, so an ayanamsa only 0.09° larger than Lahiri’s would put it on 26 May 2027, and count (a) would then agree with count (b). The 2028 entry sits 3 hours 48 minutes after midnight; an ayanamsa 0.15° smaller would move it back to 24 May. The ayanamsa page gives the Lahiri value the site uses and how far a difference moves each graha’s ingress.

Rohini Entry Dates, 1950 to 2050

For a longer view the site’s own Sun formula was scanned for the crossing of 40° in every year from 1950 to 2050. It reproduces all 6 DE421 Rohini and Mrigashira entries for 2026 to 2028 on the same date and within 12 minutes, so the scan is printed as dates only. Of the 101 years, 3 entries fall within 20 minutes of an IST midnight (1961, 2004, 2043), close enough that the scan cannot be trusted to name the day, and they are left out of the count.

25 May holds 82 of the 101 years. Among the dated years, 24 May appears only up to 2000, and from 1960 on only in leap years, because 29 February pulls the date back by a day. 26 May appears in the dated count only in 2047.

Why the Date Slowly Moves Later

The scan’s average interval from one Rohini entry to the next is 365 days 6 hours 9 minutes: the Sun’s return to the same sidereal point. A common year of 365 days is shorter than that, so the entry comes about 6 hours later on the clock each common year, and a leap day sets it back. Between 1950 and 2050 every fourth year is a leap year, 2000 included, so the calendar averages 365 days 6 hours, and the entry ends up about 9 minutes later each year, some 15 hours over the century. That is why 24 May turns up only in the first half of the range and 26 May only in the 2040s.

Over longer spans the Gregorian calendar leaves out three leap days in every 400 years, and its average year is about 20 minutes shorter than the Sun’s sidereal return computed here. At that rate the Rohini entry, and with it the start of Nautapa, falls about a day later by the calendar every 73 years. The same drift moves all the Sun’s sidereal entries; the Vedic Sun sign dates page shows it for the twelve signs, and the Uttarayan and Dakshinayan page sets the sidereal and tropical counts of the year side by side.

Nautapa Start Dates, 2026 to 2035

Dates only. The rows marked DE421 come from the ephemeris table; the rest from the scan. Count (b) uses New Delhi sunrise.

In every year of the table the Sun enters Rohini on 25 May. The two counts agree only in 2028 and 2032, when the entry comes in the hours before dawn; in the other years it comes after sunrise and count (b) starts a day later. For the Sun’s twelve sign entries of 2027 there is Sun transit 2027. The nakshatra itself has its own article, Rohini nakshatra.

What This Page Does Not Give

Searches for Nautapa ask about heat, rain, food, rituals and what to do or avoid. None of that is here. A nakshatra entry is a point on the ecliptic, and nothing on this page measures temperature, rainfall or anyone’s health; summer heat is a matter for the India Meteorological Department’s forecasts, not for a nakshatra. The page prints dates and the arithmetic behind them, nothing more.

In Brief

• Nautapa 2027: Sun enters Rohini at 21:39 IST on 25 May 2027; nine days 25 May to 2 June 2027 counting the entry date, or 26 May to 3 June 2027 counting from the next sunrise
• Nautapa 2028: entry at 03:48 IST on 25 May 2028, before sunrise; both counts give 25 May to 2 June 2028
• Sun’s stay in Rohini: 13 days 21 hours, so the nine days end inside it
• Ayanamsa: each 0.1° moves the entry about 2.5 hours; the instants above are Lahiri
• 1950–2050: 25 May in 82 of 101 years, 24 May in 15, 26 May in 1

In Hindi: नौतपा 2027 और 2028: सूर्य का रोहिणी प्रवेश और नौ दिन.