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Identification of the Stars of the Saptarṣi Maṇḍala and Its Vicinity

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Identification of the Stars of the Saptarṣi Maṇḍala and Its Vicinity Journal of Astronomical History and Heritage, 22(2), 294‒300 (2019). IDENTIFICATION OF THE STARS OF THE SAPTARṢI MAṆḌALA AND ITS VICINITY B.S. Shylaja Jawaharlal Nehru Planetarium, High Grounds, Bengaluru 560001, India. Email: [email protected] and Venketeswara R Pai Indian Institute of Science Education and Research, Pune 411008, India. Email: [email protected] Abstract: The Saptarṣi Maṇḍala is the group of the seven main stars in the constellation Ursa Major. It is familiar to all the observers of the northern hemisphere, and is cited in both astronomical and non-astronomical texts. Here, we study the positions of the seven stars based on their co-ordinates provided in different star catalogues. This also helps in fixing the epochs of the catalogues. We also discuss the relatively unknown constellations Trivikrama and Śiśumāra (or Śiṃśumāra). We also discuss the constellation corresponding to Ursa Minor, as a fish with the Pole Star at its centre. Keywords: Ursa Major, star names in Indian texts, Saptarṣi Maṇḍala, identification of Śiśumāra, Dhruva, Pole Star, the constellation Trivikrama 1 INTRODUCTION [northern distances from the ecliptic] of the [seven] sages are, in order, 55, 51, 50, 56, The seven stars of the constellation Ursa Major 57, 60, and 60 [degrees]. Their motion is 8 are very well known in India by the name Sap- arc minutes [per year] eastward. [With] their tarṣi Maṇḍala. References to this group can be exceedingly small north-south motion [the seen in the literature of almost all languages in seven sages] complete a revolution in 2,700 India. The names of these seven sages are years. (Colebrook, 1809: 360‒361). also equally well known. The mythological stor- Sule et. al. (2007) cite Srīratnagarbha as the ies give different sets of names, while the ast- first text stating Arundhati, along with Vasiṣṭha ronomical texts refer to them as the seven ṛṣis (Mizar and Alcor). As we see below there seems or munis. In fact, in most of the mathematical to be no consensus on the order of names. and astronomical texts, in the bhūta-saṅkhyā Generally Marīci is always cited as the last. system of depicting numbers (where some spe- The catalogues used here have followed the cific objects denote individual numbers, for ex- order of increasing E-W coordinates, Dhruvaka. ample the word ‗eyes‘ refers to the number 2), the number 7 is represented by the word muni. We use the list cited above (Colebrook, 1809) because it specifically gives the names of the The seven stars can be identified in the sky stars and their relative coordinates. It should be without any ambiguity. Therefore, we can use noted that instead of providing the Dhruvaka (D) them to fix the coordinates of other fainter stars. and Vikṣepa (V) separately for each star he References to their positions are given in the quotes only the differences. The coordinates D context of the heliacal rising with the star Reg- and V used here are different from those used ulus (Maghā) which has been used by various in contemporary European texts, and refer to scholars to fix the epoch of specific texts (e.g. polar longitudes and latitudes (Saha and Lahiri, see Abhyankar, 2007; Saha and Lahiri, 1954). 1954). For objects close to the equator or ecliptic the error between these and the ecliptic 2 THE STAR LIST latitude and Vikṣepa is not large (Pai and The names of the individual stars differ in the Shylaja, 2016). However, for these seven stars texts. We have used Āṅgirasa, Kratu, Marīci with latitudes more than 45° from the ecliptic, Pulaha, Pulastya, Pulastya Atri and Vasiṣṭha, the differences are large; a small error in mea- with their coordinates as defined in the sācalya surement can lead to a very large deviation from samhitā: the position, as will be shown below. Vasiṣṭha is 10 degrees west of Marīci. The other source of star lists for this study is Āṅgirasa is 7 [degreeoridnatess] west of the the star dials of astrolabes. A large variety of [star Vasiṣṭha]. Atri is 8 [degrees] west [of these instruments from India has been catalogu- Āṅgirasa]. Pulastya is 3 [degrees] west [of ed (Sarma, 2017), and many of them provide Atri]. Pulaha is 10 [degrees west of Pulast- ya]. [The star] Kratu is 3 [degrees from lists of stars although these are generally re- Pulaha]. At the beginning of the yuga, Kratu stricted to a small number of bright stars. It is was 5 degrees north at the beginning of interesting that most of the stars in Saptarṣi Visṇu‘s nakṣatra [that is, 'Sravaṇa]. The Maṇḍala do not appear in the star lists on the Page 294 B.S. Shylaja and Venketeswara R. Pai Stars of the Saptarṣi Maṇḍala and its Vicinity majority of astrolabes. Many astrolabes only from 0° to 3° listed under Aries (Meṣa), those cite Marīci, a few also cite Vasiṣṭha, while a few between 30° and 60° grouped under Taurus more cite three of the seven stars. Only one of (Vṛṣabha), and so on. Perhaps this was achiev- them (D001, the large astrolabe at Jaipur) lists ed using another table-top device like an arm- all seven stars, but only the names are written illary sphere. The values of Dhruvaka are given on the rete and the coordinates are not includ- within that rā'si in degrees (bhāga/vibhāga) and ed. Consequently, we could not use this astro- its fraction. Therefore, to get the longitude we labe for our research. need to add 30 or a multiple of 30 as the case may be. Furthermore, the precession correction Mahendra Sūri referred to the astrolabe as also has to be added. The result is that for Yantrarāja, and in CE 1370 he prepared a man- some stars in UMa, we may have to add n × 30 ual, written in Sanskrit, for its use. The proced- and for some we may have to add (n + 1) × 30. ural details, including a list of stars, were trans- lated from the original Persian text, and included We converted all the D and V values to the epoch of the coordinates. Subsequently Right Ascensions and Declinations so as to Malayendu, a pupil of Mahendra Sūri, wrote a facilitate the comparison with conventional star commentary on this text in CE 1377‒1382 catalogues and software like Stellarium, Celest- (Ôhashi, 1997). The star list in this manual pro- ia or Night Shades (the methods are described vides various observed parameters like the by Abhyankar, 2007; Chandra Hari, 2007; and readings on the instruments, the corrected read- Saha and Lahiri, 1954). ings for the epoch and also measured values of Here we encountered another problem. Al- the maximum altitude. The Pārasika name (the though the times of composition of the two texts original Persian name written in Sanskrit script) are the fourteenth and fifteenth centuries, the is helpful in identifying very faint stars, though copies available to us are more recent. The tab- they are very distorted. This text does not con- ulated values in Nityānanda‘s work do not corr- tain the names of the seven stars being re- espond to his epoch. As was pointed out by searched here, but it does provide a very good Pingree (1996), they have been borrowed from resource for the cross-verification of the coord- the original text. The manuscript used by us inates of stars. was procured from the Bhandarkar Oriental Re- Nityānanda wrote another text titled Sidd- search Institute in Pune, and was composed in hāntarāja (which has still not been published), Vikrama-saṃvat 1696 which corresponds to CE which lists the coordinates of about 84 stars; 1638. Padmanābha‘s tables again do not corr- espond to the epoch of his time. He mentions and it is possible to identify almost all of them (Shylaja and Pai, 2018b). This source gives ad- that 15° needs to be added to the Dhruvaka ditional information on the brightness scale (mag- values. Ôhashi (1997) has studied two manu- nitude) such as ekamāna, dvimāna and so on. scripts, and the second one included the list of Thus, it is a very reliable source for fixing the the stars under study here. They have been names and positions of stars. called ‗minor stars‘ and appear in only one man- uscript (Lucknow, 45888); there is a colophon The book Yantra-Kiraṇāvali, authored by Pad- that follows this tabulation giving the date as manābha in the fifteenth century also provides a samvat 1634, marga'sira masa, śukla pakṣa, list of stars. As always, the 27 stars of the ṣaṣti, bṛghuvāra corresponding to CE 26 De- zodiac help in fixing the positions. cember 1576. For ease of comparison, we con- We have calculated the coordinates of the verted the D and V values to Right Ascension Saptarṣi Maṇḍala stars using the star-lists pro- and Declination (as explained in Pai and Shy- laja, 2016) corresponding to CE 1634. vided by Nityānanda and Padmanābha, and these given in Table 1. Nityānanda‘s list also gives co- The results are displayed in the Table1 and ordinates for three pairs of stars, designated Yug- are also represented in the star map in Figure 1; maka, Yugma and Yugmaka, which are situated the letters N and P are used to indicate the within the boundary of the constellation of Ursa positions provided by the two sources. Major, and they helped us in fixing the correc- tion for the epoch. The entries in Table 1 drawn 3 THE CATALOGUES from Padmanābha‘s list are indicated by a P, We found no ambiguity in the identification of while those taken from Nityānanda‘s list are mark- the stars, but the large errors in the declination ed with an N.
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