The 27 nakshatras are grouped into seven classes: Sthira (fixed: Rohini and the three Uttaras), Chara (movable: Punarvasu, Swati, Shravana, Dhanishta, Shatabhisha), Laghu (swift: Ashwini, Pushya, Hasta), Mrudhu (tender: Mrigashira, Chitra, Anuradha, Revati), Sadharana (mixed: Krittika, Vishakha), Vajra or Ugra (fierce: Bharani, Magha and the three Purvas) and Theekshana (sharp: Ardra, Ashlesha, Jyeshta, Moola). Kalaprakasika (1917, pp. 149–150) and Muhurta Chintamani (pp. 49–52) give the same 27 assignments. But the class alone does not pick a muhurtham: Kalaprakasika gives each occasion its own star list, and those lists mix the classes.
☕ What the classes are, and what they are used for
Each nakshatra has a nature. Muhurtha books sort the 27 into seven classes by that nature. Two books in this tradition, Kalaprakasika (N. P. Subramania Iyer's 1917 English edition) and Muhurta Chintamani (Rama Daivajna, 1600), put every one of the 27 stars in the same class. They belong to one tradition, so their agreement shows how widely the table was handed down, not two separate proofs of it.
Kalaprakasika names a class in only a few rules. Things pledged, or money lent at interest, under a mixed, fierce or sharp star do not come back (p. 149). Doors are fixed under a movable or fixed star (p. 160), the churning dasher is first used under a movable star (p. 161), and some medical treatments begin under swift, fierce or movable stars (pp. 198–199). Note that on pp. 160–161 the book counts Ashwini, Pushya and Hasta as movable, although its own table (p. 150) puts them in the swift class.
You will often read a shorthand: fixed stars for houses, movable stars for vehicles and travel, swift stars for gold. For most occasions Kalaprakasika does not choose by class. It prints that occasion's own list of best stars, and every list mixes classes. Its housewarming list has all four fixed stars and eight others. Its travel list puts Swati, a movable star, among the stars to avoid. Its marriage list includes Magha (fierce) and Moola (sharp). So read a star's class as a general nature, and use the occasion's own list to choose a day.
Kalaprakasika's own lists, occasion by occasion
- Housewarming (ch. XXVI, p. 168): Rohini, Mrigashira, Punarvasu, Pushya, Uttara Phalguni, Hasta, Anuradha, Uttara Ashadha, Shravana, Shatabhisha, Uttara Bhadrapada, Revati
- Riding a horse or any other conveyance (ch. XXVII, p. 171): Ashwini, Rohini, Mrigashira, Punarvasu, Magha, Uttara Phalguni, Hasta, Chitra, Swati, Anuradha, Uttara Ashadha, Shravana, Uttara Bhadrapada, Revati
- Travel (ch. XXIX, p. 177): Mrigashira, Pushya, Hasta, Anuradha, Dhanishta, Shravana, Revati, Ashwini
- Marriage (ch. XIV, p. 116): Rohini, Mrigashira, Magha, Uttara Phalguni, Hasta, Swati, Anuradha, Moola, Uttara Ashadha, Uttara Bhadrapada, Revati
- Laying up treasure (ch. XXI, p. 146): Mrigashira, Ardra, Pushya, Uttara Phalguni, Hasta, Anuradha, Uttara Ashadha, Shravana, Dhanishta, Shatabhisha, Uttara Bhadrapada
- Lending at interest or giving in pledge: any mixed, fierce or sharp star (p. 149)
- Giving away or lending gold: Krittika, Magha, Moola, Shatabhisha, Uttara Phalguni, Punarvasu, or your own birth star (p. 149). Note that this list includes movable and fixed stars
- Starting a journey: Bharani, Krittika, Ardra, Ashlesha, Magha, Purva Phalguni, Swati, Vishakha, Jyeshta, Purva Ashadha, Purva Bhadrapada, and your own birth star (p. 177). The book allows each of these once a stated number of ghatikas of the star has passed
Frequently Asked Questions
Are fixed stars for housewarming and movable stars for a vehicle?
That is a common shorthand, but it is not how Kalaprakasika chooses for these occasions. Its housewarming list (p. 168) has all four fixed stars and eight stars from other classes. The 1917 book has no chapter on buying a vehicle. Its nearest rule is for riding 'on horseback or any other conveyance' (p. 171): fourteen best stars from five classes, including the movable Punarvasu, Swati and Shravana but not Dhanishta or Shatabhisha. Separately, it times 'using a new vehicle' by Venus's position, not by the star (p. 155).
What does Kalaprakasika say about wealth and gold?
Kalaprakasika's chapter on laying up treasure (ch. XXI, p. 146) names Mrigashira, Ardra, Pushya, Uttara Phalguni, Hasta, Anuradha, Uttara Ashadha, Shravana, Dhanishta, Shatabhisha and Uttara Bhadrapada. It warns against giving gold away or lending it under Krittika, Magha, Moola, Shatabhisha, Uttara Phalguni, Punarvasu or your own birth star (p. 149). It has no rule for buying gold by name, and it does not name 'Guru Pushya'; the nearest is a Thursday under Pushya as the best time to buy sheep (p. 149).
Does the app use these classes?
Yes. The day score adds a weight for the day's star by its class: fixed and tender stars count highest, then swift, then movable; mixed stars count nothing; fierce and sharp stars count against the day. It is one factor among several, alongside the tithi, the Amritadi yogas and your own tara.
From the sources
The class table as Kalaprakasika prints it, and the star counts it treats as adverse.
📖 The seven classes (Kalaprakasika pp. 149–150)
Spellings as the 1917 edition prints them. Muhurta Chintamani (pp. 49–52) gives the same 27 assignments under its own names: Dhruva, Chara, Ugra, Mishra, Kshipra, Mridu and Tikshna.
- Sthira (fixed): Rohini, Utharapalguni, Utharashada, Utharabadhrapadha.
- Chara (movable): Punarvasu, Swathi, Sravana, Sravishta, Sathabis.
- Laghu (swift): Aswini, Pushya, Hastha.
- Mrudhu (tender): Mrigasirsha, Chithra, Anuradha, Revathi.
- Sadharana (mixed): Visakha, Krithika.
- Vajra (fierce): Bharani, Magha, Purvapalguni, Purvashada, Purvabadhrapadha.
- Theekshana (sharp): Ardhra, Aslesha, Jyeshta, Mula.
⭐ Your own birth star still matters
A good class does not make a day good for everyone. Kalaprakasika (p. 227) treats your birth star, and the 3rd, 5th, 7th, 10th and 19th stars counted from it, as adverse for you, and then lists the planetary positions that cancel that. The app's tara count, from your birth star, is how your personal score reflects this.