Research notes · Wisdom & lineage · 5,421 words

#Tamil Siddhars and South Indian sage-astronomer lineages (Pancha Pakshi, Pulippani, Vakya/Katapayadi, Parahita)

Research date: 2026-10-14. Archive.org identifiers below were checked against the live archive.org metadata API on that date. "PD" means public domain. Under Indian copyright, a work is protected for the author's life plus 60 years. In the US, works published before 1931 are PD. Where an archive.org item carries a CC0 or PD tag, the uploader added it. That tag is not proof of PD status.

Legend vs history labels used below: [LEGEND] = traditional or devotional attribution. [HISTORY] = dated by documentary or scholarly evidence. [UNVERIFIED] = a claim found only in popular or vendor sources.

#1. What survives, where it is readable on archive.org, and PD status (incl. the variant lists of the 18 Siddhars)

#Takeaway

A large, readable Tamil corpus survives on archive.org. It includes several 19th-century printed editions of Pancha Pakshi texts attributed to Agastya, Bogar and Romarishi, dated 1863–1934, and these are clearly PD. It also includes a Tamil Virtual Academy scan of Pulippani Jothidam 300 with usable OCR. The Kerala/Tamil vakya astronomy texts survive too: the Vakyakarana in a critical edition, plus palm-leaf copies. The "18 Siddhars" are not one fixed list. Several incompatible lists exist, and the astrology-relevant names in them (Bogar, Pulippani, Agastya, Kakabhujandar) shift between those lists.

#Cited Findings

The 18 Siddhars: variant lists

• The list in the Abithana Chintamani encyclopedia, as given on Wikipedia, is: Nandi, Tirumular, Agastya, Kalangi Nathar, Patanjali, Korakkar, Sundaranandar, Konganar, Sattaimuni, Vanmikar (Valmiki), Ramadevar, Dhanvantari, Idaikaadar, Machamuni, Karuvurar, Bogar, Pambatti, Kuthambai. The same page notes that Agastya himself says there were many Siddhars before and after these 18. Pulippani is not on this list. — Wikipedia: Siddhar
• A second "Navagraha" list pairs two Siddhars with each planet, and Wikipedia tags it "citation needed": Moon – Sivavakkiyar, Kambili; Mars – Bhogar, Pulippani; Jupiter – Kagabhujanga (Kakabhujandar), Agapai; Rahu – Alugani, Pambatti; Ketu – Sattaimuni, Kudambai; Mercury – Vallalar, Idaikadar; Sun – Pattinathar, Kaduveli; Venus – Kanjamalai, Sennimalai; Saturn – Kapilar, Karuvurar. This list includes Vallalar (Ramalinga Swamigal, 1823–1874), which shows it is a modern construction. — Wikipedia: Siddhar
• A 2007 snapshot of the same Wikipedia article gave yet another 18 (Agastyar, Bogar, Korakkar, Kailasanathar, Sattaimuni, Tirumoolar, Nandhi, Poonaikannar, Konganar …). It also gave unsourced dates, such as Karuvurar in the 10th century CE and Pambatti in the 15th century CE. — Wikipedia 2007 mirror
• The user's brief also lists Kamalamuni, which appears in other popular lists. Pulippani and Kakabhujandar appear only in some lists. — compare the lists above.

Pulippani Jothidam (Pulippani 300)

• tdl.49994-nuul-pulippaanni-mkaamunnnivr-tiruvaaymlrntrulliy-cootittm-munnuurru: Pulippani Mahamunivar Tiruvaymalarntharuliya Sothidam Munnuru, a Tamil Virtual Academy scan with a PDF and djvu OCR text. The catalogue keywords list its topics: 12 rasis, 27 nakshatras, friendship/enmity, own sign, exaltation/debilitation, Sakata yoga, travel abroad, Maharaja yoga, planetary conjunctions, and dasa-bhukti results. The title page says the edition was checked by Trichy astrologer Rangasami Pillai and published in Chennai by S. N. Devaraja Nayakar, with the printed year illegible in the OCR. — archive.org metadata; full text
• XjKB_pulippani-jothidam-300-pulippani-siddhar-tamil-b-r-balakrishna-nayakar: Pulippani Jothidam 300, B. R. Balakrishna Nayakar edition. It was scanned by Muthulakshmi Research Academy from the Oriental Research Institute, Mysore, and the uploader tagged it CC0. Its language is mis-tagged "san"; the text is Tamil. — archive.org
• adv-tech-of-pulippani-jyotidham: Advanced Techniques of Pulippani Jothidam by Ashutosh Bhardwaj (English). The book carries an explicit copyright notice, so it is not PD; treat it as a secondary reference only. It confirms the text has 300 verses and states its own approach as Yoga, Dasha and Transit. — archive.org
• Many more Pulippani items on archive.org are medical texts (Vaittiyam 500, 1887, 1903, 1912, 1924 editions), not astrology. Examples are dli.rmrl.000422 (1887) and dli.rmrl.000255a (1912). — archive.org search results, e.g. dli.rmrl.000422

Pancha Pakshi (Tamil, printed 19th c., PD)

• pacapacicstiramm00akas: Panchapatchi chastiram mulamum nanachara nul mulamum uraiyum, attributed to Akastiyar (Agastya). It was printed in Chennai by Intuniti Achchukkutam in 1863, runs to 88 pages, and is from the François Gros collection at the University of Toronto. PD. — archive.org
• dli.rmrl.007550: Panchapatchi chastiramulamum atarkiyainta chakkarankalum ("…with its chakras/tables"), attributed to Agastya. It was printed in 1867 at Meynnanachuriyotayavilacha press, and it is bundled with the Nanachara nul, framed as Shiva teaching Uma (svara/breath lore). It reprints an earlier edition by Chetanapattu Ramasami Kavirayar. Roja Muthiah Research Library collection. PD. — archive.org
• Other Pancha Pakshi editions held by Roja Muthiah: dli.rmrl.000451_images (1879), dli.rmrl.007543 (1880) and dli.rmrl.007547 (1934). — archive.org search, e.g. dli.rmrl.007543
• Romarishi (Romaharsha) Vinadi Pancha Pakshi, which works to the vinadi (24-second) scale, survives in several editions: tdl.25389-…, tdl.2398-…, tdl.1368-500 (Romarishi Pancha Pakshi 500), kvc-0354-vinaadi-pajasapatchi-mulamum-1934 (1934) and acc.-no.-44926-…-2020 (2020 reprint). — archive.org kvc-0354
• tdl.27363-nuul-pookmunnnivr-tiruvaaymlrntrulliy-pnycpttci-caastirm: Bogar's Pancha Pakshi Sastram. A 2024 edition with commentary is acc.-no.-44757-panjapatchi-sashthiram-2024, which is not PD. — archive.org
• tdl.22647-… / tdl.8328-…: Valaiyarul Patinen Siddharkal Pancha Pakshi Sastram – urai & vilakkam, a compilation attributed to the 18 Siddhars, with commentary. — archive.org
• gc-sh3-0003: Ashtatikkin arutam, panchapatchi arutam, anchaneyararutam, jeyamunivararutam, valmikararutam (1922), a collection of horary (arudam) methods. — archive.org
• tdl.50083-…: Siddhar Rahasyam ennum Aruda Alankaram (mulam + urai), a Siddhar horary text. — archive.org search result for பஞ்சபட்சி

Pancha Pakshi in other languages

• Telugu: pancha-pakshi-kerala-prashna-sastramu (Vaddadi Veerraju?) and lSCl_sthula-sukshma-pancha-pakshi-ashta-dhikkula-aruda-shastram-telugu-by-chandra-gir…. Sanskrit: IQVd_panchapakshi-shakun-mahadev… (Lal Bahadur Shastri Sanskrit University manuscript), kzvo-pancha-pakshi-sanskrit-jyotisha-paper-manuscript-u, and atdz_1.-pancha-pakshi-shakuna-devanagari-kashi-maharani…. Kannada/Sanskrit: pfcz-73-aneka-chintamani-…-panchapakshi-shastra-kannada-and-sanskrit. — archive.org advancedsearch "pancha pakshi" / "panchapakshi"
• Wikipedia records a Sanskrit Pancha Pakshi work ascribed to Agastya, with Telugu- and Grantha-script manuscripts in the Thanjavur Palace library. It also cites Shivarama Pati's 1906 edition Pancha-pakshi-prashna, a Tamil Ahattiyar-pancha-pakshi-suttira manuscript at the Government Oriental Manuscripts Library in Chennai, and further Sanskrit works by Krishna, by Gangadhara (Pancha-pakshi-prakasha) and by Narayana Bhatta (Pancha-pakshi-shakunavali). Its sources are Pingree's Census of the Exact Sciences in Sanskrit and Jagadisa Ayyar's South Indian Customs. — Wikipedia: Pancha Pakshi Shastra
• English: Biorhythms of Natal Moon: Mysteries of Panch Pakshi by Dr. U. S. Pulippani (pen name of Prof. Sundara Varadachary), with a foreword by K. N. Rao (Ranjan Publications, 1993). It is on archive.org as jyotish-1993-u.-s.-pulippani-k.-n.-rao-biorhythms-of-natal-moon in the "folkscanomy" collection, but it is in copyright. The book contains 100 computed tables with 2,500 entries. — archive.org
• Source Library (sourcelibrary.org) catalogues the 1863 Toronto edition. It lists two English translations: a 1991 The Science of Panchapakshi by U. S. Pulippani (Ranjan) and a 1993 Pancha Pakshi Shastra by K. N. Saraswathy (Kadalangudi). — sourcelibrary.org

Other Siddhar astrology and related texts on archive.org

• Bogar 7000 (Saptha Kaandam): bogar-7000-sapthakaandam (dated "1823" in the metadata, which is doubtful and probably the uploader's guess), Bogar7000-1mKaandam, Bogar70002mKaandam and Bogar70003mKaandam (1975 editions, Tamil). These are 1975 prints, so not PD in India. — archive.org
• 20250802_20250802_1727: Nandidevar aruliya Sothida Marmam (Tamil). This is a 2025 upload of an undated edition, and its PD status is unknown. — archive.org
• agasthiyarnaadi ("Agasthiyar Nadi") is an empty promotional item with no files. — archive.org
• Kalaprakasika (Tamil muhurta classic): in.ernet.dli.2015.45999 (1917), ZBAx_kalaprakasika-n-p-iyer-tamil-lawley-press (N. P. Iyer, tagged CC0), kalaprakasika (1982, tagged PD Mark) and pli.kerala.rare.10320. — archive.org search "kalaprakasika"
• Tamil vakya panchangams: bqfm-manonmani-vilasa-suddha-vakya-panchangam-sarvajitt (Suddha Vakya Panchangam, Sarvajit year, Annavaiyangar, Manonmani Vilasam Press, Chennai, 1947, tagged CC0) and zjye-tirukkovil-anushtana-vakya-panchangam-dasavidha-po… (a temple-ritual vakya panchangam with the 10 marriage poruthams). — archive.org

Kerala/Tamil vakya astronomy texts on archive.org

• vakyakaranawithlaghuparkasikasudararajaed.kuppannasastrit.s.sarmak.v._865_t: Vakyakarana with Sundararaja's Laghuprakashika, edited by T. S. Kuppanna Sastri and K. V. Sarma (1962 critical edition with English translation). The uploader tagged it CC0, but as a 1962 work its Indian copyright is doubtful, so verify before reusing it. — archive.org; edition details from Wikipedia: Vakyakarana
• raswhish68-69a: Vakyakaranadipika, a palm-leaf manuscript (c. 1800?) from the Whish Collection at the Royal Asiatic Society. It contains Sundararaja's short commentary on the Vakyakarana in 5 adhyayas plus astronomical tables. PD. — archive.org
• kgsi_a-bibliography-of-kerala-and-kerala-based-astronomy-and-astrology-by-k-v-sa…: K. V. Sarma, A Bibliography of Kerala and Kerala-based Astronomy and Astrology (in copyright). Also: history-of-astronomical-science-in-kerala-priya-kurian (PhD thesis, CC BY-NC-ND), karanapaddhati-…-venketeswara-pai-k.-ramasubramanian… (modern, in copyright), in.ernet.dli.2015.406081 (Karanapaddhati, 1920 edition), and httpswww.ijtsrd.com…vararuchi-and-madhavas-ch (Hindi journal article on the Chandravakyas of Vararuci and Madhava). — archive.org search results

What a Pulippani verse looks like (checked in the TVA OCR text)

• The kaappu (invocation) of Pulippani 300 invokes the feet of "Siddhar Bogar". Many verses end with a refrain that the poet speaks "by the grace of Bogar", which presents Pulippani as Bogar's disciple. — TVA djvu text
• The dasa section uses the standard Vimshottari periods: Sun 6 years, Moon 10, Mars 7, Rahu 18, Mercury 17. It gives the Sun-in-Sun bhukti as 108 days. Each dasa/bhukti stanza lists effects, for example fire danger, loss of wealth, the father's death, and eye trouble in Sun dasa. — same source
• Bhardwaj's English book gives a sample rule: Sun and Mercury together in the 1st, 4th or 8th house, aspected by the lords of the 9th and 10th, give a royal life (his reading of verse 135). — archive.org

#Inferences

• For a site, the strongest PD primary sources are the 1863 and 1867 Agastya Pancha Pakshi prints (pacapacicstiramm00akas, dli.rmrl.007550) and the 1922 Arudam collection. The Pulippani 300 TVA scan is probably PD as an old print, but its year needs confirming from the page images.
• Pulippani 300 is a mainstream Parashari-style text (yogas, dasa results) written in Tamil siddha verse. Its distinctive part is the Bogar-lineage framing and the Tamil verse form, not new techniques.
• Mark the Navagraha "18 Siddhars" list as a modern devotional construct, since it includes the 19th-century Vallalar.

#Gaps

• The printed year of the TVA Pulippani 300 edition was not legible in the OCR, so check the PDF title page.
• I did not find a Kakabhujandar astrology text on archive.org (searches for "kakabhujandar"/"kakabujandar" returned nothing). Tamil-script searches (காகபுசுண்டர்) were not run.
• I did not verify Bogar 7000's astronomical content or the claims made about it.
• I did not check Project Madurai for PD Siddhar texts.

#2. Pancha Pakshi: exact rules (birth bird, day/night yamas, activities). Is it implementable?

#Takeaway

Yes. The core is a deterministic lookup. The birth bird comes from the birth nakshatra and the paksha. The day and night are each split into 5 equal yamas measured from actual sunrise and sunset. In each yama, each of the 5 birds does one of 5 activities, and the starting bird depends on the weekday and the paksha. The bright-half tables follow a clean rotation that can be coded and checked. The dark-half tables in the one English source I could read have OCR or printing inconsistencies, and sources disagree on details, so cross-check against the PD Tamil prints. Also show a "traditions vary" note in the product.

#Cited Findings

Basic terms

• Five birds: Vulture/hawk (Tamil valluru), Owl (antai), Crow (kakam), Cock (kozhi), Peacock (mayil). Five activities, from strongest to weakest: Ruling, Eating, Walking, Sleeping, Dying. — Wikipedia: Pancha Pakshi Shastra
• The 1863 Tamil print uses these activity names: unti (eating), natai/pokku (walking), aracu (ruling), tukkam/tuyil (sleeping), chavu (dying). It also has a separate table that assigns birds by the first vowel of a person's name (akaram first …), with separate purva-patcham (bright) and amara-patcham (dark) tables. The OCR is too noisy to read the exact vowel table. — 1863 djvu text

Birth bird by nakshatra and paksha (from Pulippani/Rao 1993, pp. vi–vii)

• Bright half (Shukla): Vulture = 1–5 (Ashwini to Mrigashira); Owl = 6–11 (Ardra to Purva Phalguni); Crow = 12–16 (Uttara Phalguni to Vishakha); Cock = 17–21 (Anuradha to Uttara Ashadha); Peacock = 22–27 (Shravana to Revati). — Biorhythms of Natal Moon, archive.org text
• Dark half (Krishna): same bird order, but counted backwards from Revati. Vulture = 27–22, Owl = 21–17, Crow = 16–12, Cock = 11–6, Peacock = 5–1. — same source
• Worked examples in the book: Uttara Ashadha in the bright half gives Cock, and Purva Phalguni in the bright half gives Owl. — same source
• Paksha definition used: the bright half runs from the day after new moon to full moon. The dark half runs from the day after full moon up to and including the new-moon day. — same source (ch. "Common Features and Conventions", item 12)
• Conflicting simplified table: dekhopanchang.com uses one table with no paksha split (Vulture 1–5, Owl 6–10, Crow 11–15, Cock 16–20, Peacock 21–27). This contradicts the 5-6-5-5-6 split above. — dekhopanchang
• astrogle.com defines Shukla paksha as running full moon to new moon, which is the reverse of the standard definition. — astrogle

Time division

• Day = sunrise to sunset, night = sunset to sunrise. Each is split into 5 yamas of 6 ghatikas each, which is 2 h 24 min if the day is exactly 12 h. The book says to shift the slots to the actual sunrise and sunset. — Biorhythms of Natal Moon
• Each yama is split again into 5 sub-activities ("Ruling in Ruling" … "Dying in Dying"). Ruling-in-Ruling is the strongest and Dying-in-Dying the weakest. The four combinations of Ruling and Eating are always favourable. The book also weighs whether the sub-period's bird is a friend or enemy of the main bird. For example, a friend bird Ruling with an enemy bird Eating in a sub-period is downgraded to "medium". — same source

Bright half, daytime (transcribed from the book)

• Within a yama, the activities run in the order Eat, Walk, Rule, Sleep, Die. The "eater" bird takes the first, and the rest go to the following birds in the cycle V → O → Cr → Ck → P.
• The next yama's eater is the bird before the current one: V → P → Ck → Cr → O.
• First-yama eater by weekday: Sun/Tue = Vulture; Mon/Wed = Owl; Thu = Crow; Fri = Cock; Sat = Peacock.
• Example, Sun/Tue yama 1: Vulture eats, Owl walks, Crow rules, Cock sleeps, Peacock dies. Yama 2: Peacock eats, Vulture walks, Owl rules, Crow sleeps, Cock dies. — Biorhythms of Natal Moon

Bright half, night-time (transcribed)

• With eater X, the bird before X rules, the one before that dies, the next one back walks, and the next one back sleeps.
• The next yama's eater is the bird after the current one: Cr → Ck → P → V → O.
• First-yama eater by weekday: Sun/Tue = Crow; Mon/Wed = Cock; Thu = Peacock; Fri = Vulture; Sat = Owl.
• Example, Sun/Tue night yama 1: Crow eats, Owl rules, Vulture dies, Peacock walks, Cock sleeps. — same source

Ruling birds and death days, bright half

• The book states that the bird eating in the first yama is the "ruling bird" of that day or night. Bright-half ruling birds: Vulture = Sun/Tue days, Fri nights; Owl = Mon/Wed days, Sat nights; Crow = Thu days, Sun/Tue nights; Cock = Fri days, Mon/Wed nights; Peacock = Sat days, Thu nights. — same source
• "Immune" (death, padu) days in the bright half, which hold for the whole day and night: Vulture = Thu and Sat; Owl = Sun and Fri; Crow = Mon; Cock = Tue; Peacock = Wed. On these days a person whose birth bird it is should avoid important work. — same source

Dark half, daytime (transcribed, but the OCR has errors)

• With eater X, the bird two places back dies, the next bird forward sleeps, the previous bird rules, and the bird three places back walks. Example, Fri yama 1: Vulture eats, Cock dies, Owl sleeps, Peacock rules, Crow walks.
• The next yama's eater is two places forward: V → Cr → P → O → Ck.
• First-yama eater by weekday: Sun/Tue = Cock; Mon/Sat = Peacock; Wed = Crow; Thu = Owl; Fri = Vulture.
• In the Sun/Tue dark-day group, yama 3 is printed as Peacock-eats and repeats in yama 4. The rotation predicts Crow for yama 3, so this is either a transcription or an original error. — same source

Dark half, night-time (partial)

• With eater X, the next bird forward rules, the previous bird sleeps, the bird two places back walks, and the bird three places back dies. The next yama's eater is the next bird forward.
• Sun/Tue night starts with Vulture eating.
• The dark-half ruling and immune table is garbled in the OCR. Readable parts: Owl immune Mon; Crow immune Sun; Vulture immune Tue; Peacock immune Wed. The book says the ancient verse also gives Peacock as immune on Friday night, which it calls "controversial" and treats as neutral. — same source, ch. "Significations for Dark Half", pp. 123–124

Correspondences

• Dark half: Vulture = earth, Owl = water, Crow = fire, Cock = air, Peacock = ether.
• Each bird is also given colours, directions, body parts (e.g., Vulture = head, neck and stomach), and a dhatu/moola/jeeva class. — same source

Popular claims and caveats

• A popular claim is that the rules are kept in Tamil palm-leaf manuscripts handed down through Siddha lineages, attributed to Agastya, Bogar and Tirumular. The same site notes that no peer-reviewed studies have validated the system. — dekhopanchang
• onlinejyotish.com says that rule tables "can vary by lineage or software implementation". — onlinejyotish

#Inferences

• An implementation needs: (a) the Moon's nakshatra and the tithi/paksha at birth, (b) local sunrise and sunset, and (c) 4 lookup tables (paksha × day/night), each with a weekday start bird, a yama step, and an activity offset pattern. The bright-half patterns above are internally consistent across all 7 weekdays as I transcribed them.
• Encode the dark half as explicit tables, not as a formula, and verify them against the PD Tamil prints (1863/1867) or a second source before launch.
• Sub-period splitting: the book uses 5 sub-activities per yama, and some traditions use unequal sub-period lengths. Start with the 5 main yamas only and add sub-periods later.
• Use the rules as a non-predictive "daily rhythm" feature. The book's examples of famous deaths (Indira and Rajiv Gandhi) are retrofits, so do not present them as evidence.

#Gaps

• I did not verify the sub-period durations or proportions or the full set of 100 sub-tables.
• The complete dark-half ruling and immune table is unconfirmed because of the garbled OCR.
• I did not decode the name-vowel bird table (used in prashna, when the birth star is unknown) from the 1863 print. It needs the page images.
• I did not confirm whether the 1867 Agastya chakras match the 1993 tables.

#3. Katapayadi encoding and the Kerala lineage (Vararuci, Haridatta, Sankaranarayana): implementable?

#Takeaway

Katapayadi is a simple, fully specified cipher and is easy to build as an interactive "your name as a number" or "decode a Chandravakya" tool. Its earliest dated use is Haridatta's Grahacharanibandhana, traditionally dated 683 CE. Vararuci's authorship of the 248 Chandravakyas is legend.

#Cited Findings

• Rules: consonants map to digits in four series that start at ka, ta, pa and ya. Vowels on their own, and na and na, count as 0. In a conjunct consonant, only the last consonant counts. A consonant without a vowel is ignored. Digits are read right to left (so reverse them). Some late texts treat a standalone vowel as having no value. — Wikipedia: Katapayadi system, citing S. R. Sarma (2012), Rev. d'Histoire des Mathématiques 18

• The standard mapping, consistent with the article's examples (e.g., ba = 3; na/na/ma/sha = 5):

  • ka kha ga gha na ca cha ja jha na = 1–9, 0
  • ta tha da dha na ta tha da dha na = 1–9, 0
  • pa pha ba bha ma = 1–5
  • ya ra la va sha sha sa ha = 1–8

  — Wikipedia: Katapayadi

• Examples:

  • Melakarta raga numbers come from the raga names: Dheerasankarabharanam = 29, Mechakalyani = 65.
  • The Malayalam (Kollam) era epoch is given as the Kali-day count 1434160 in acharya vagbhada.
  • The Narayaniyam's completion date is 1712210 in ayurarogyasaukhyam.
  • The Karanapaddhati (15th c.) gives the circumference for a diameter of 10^11 as 31415926536.

  — Wikipedia: Katapayadi

• Earliest dated uses: Haridatta's Grahacharanibandhana (683 CE) and Shankaranarayana's Laghubhaskariyavivarana (869 CE). The Candra-vakyani of Vararuci is "traditionally 4th c.". — Wikipedia: Katapayadi

• Haridatta:

  • He is credited with the Parahita ("for the common good") system. Legend says it was introduced in 683 CE at the Mamankam festival at Tirunavaya.
  • It simplified Aryabhata's system, replaced Aryabhata's number notation with katapayadi, and used a 576-year (210,389-day) sub-cycle.
  • It applied the shakabda-samskara correction from Saka 444.
  • Only the Grahacharanibandhana survives; K. V. Sarma found and published it in 1954. The Mahamarganibandhana is lost.

  — Wikipedia: Haridatta

• Chandravakyas:

  • There are 248 sentences encoding the Moon's daily true longitude over 248 days, which is about 9 anomalistic months of 27.554551 days.
  • Other sets exist: 3,031 lunar vakyas, and 2,075 vakyas for the five planets.
  • Haridatta's text is the first known to use vakyas.
  • Madhava of Sangamagrama (c. 1350–1425) revised them in his Venvaroha.
  • Edition: C. Kunhan Raja, Chandravakyas of Vararuci (1946).

  — Wikipedia: Chandravakyas

• The vakyas are known as the girnashreyadi-vakyas after their opening words. They give the Moon's true longitude, correct to a minute, for each day of the 248-day cycle. — via search summary of JAHH 2019 paper

• A Kerala seminar abstract and a later study judge Madhava's values more accurate than Vararuci's, matching computed values to within about one second. — via search summary of vedicheritage.gov.in abstract

• Drigganita revision: Parameshvara (1380–1460) introduced Drigganita, a revision of Parahita. Astrologers adopted it for horoscopes and eclipses because it was more accurate, while Parahita stayed in use for fixing ritual times. — Wikipedia: Drigganita

#Inferences

• Decoding the first vakya by the rules above (my own calculation, to be verified against Kunhan Raja 1946): gi = 3, (r)na = 0, (shr)e → r = 2, ya = 1 gives the digits 3-0-2-1. Reversed, that is 1203, i.e. 12°03′. This is plausible as the Moon's daily motion near apogee.
• Feature ideas:
  • A Katapayadi converter (name to number, number to mnemonic word).
  • "Find your raga" from a melakarta number.
  • A Chandravakya explorer that shows a vakya, decodes it, and compares it with the Moon's modern ephemeris position for the same anomaly.
  • A lineage timeline for the Kerala school: Haridatta 683 → Sankaranarayana 869 → Vakyakarana c. 1282 → Madhava c. 1400 → Parameshvara → Nilakantha.
• Use Malayalam or Tamil-Grantha transliteration carefully. The rules apply to Sanskrit phonemes, so a Tamil-script name needs mapping to Sanskrit phonemes first.

#Gaps

• I did not read the full text of Kunhan Raja's 1946 Chandravakya edition on archive.org; searches for "chandravakya" returned only the Hindi article.
• The Grahacharanibandhana (Sarma 1954) was not found on archive.org.

#4. Vakya vs Drik (Thirukanitham) panchanga: history, accuracy, why both persist, and can the site show both?

#Takeaway

Tamil Vakya panchangams descend from the Vakyakarana (c. 1282 CE, probably by an author from Kanchi). That text in turn rests on the Parahita/Chandravakya tradition. Vakya almanacs are memorised-table approximations that have built up errors. The Drik (Thirukanitha) reform in Madras came in the 19th century, led by the astronomer Ragoonatha Chary and blessed by the Kanchi Matha in 1877. Both persist because temple, ritual and family custom follow Vakyam, while astrologers and those who want precision follow Thirukanitham. A site can and should show both, side by side.

#Cited Findings

• Vakyakarana:

  • Dated c. 1282 CE; internal evidence suggests the author came from Kanchi.
  • Five chapters: Sun, Moon and Rahu; planets; time, place and direction; eclipses; mahapatas.
  • It is the source book of the Tamil Vakyapanchanga, but today almanac makers mostly use later adaptations (Jyotisha Ganita Shastram, Parahita Ganitam).
  • The editors note that interpolating between its values can be several minutes off.

  — Wikipedia: Vakyakarana, citing Sastri & Sarma 1962 and Chandra Hari 2001

• Sundararaja (c. 1500, a contemporary of Nilakantha) wrote the commentary. Tamil almanac makers use the text to produce vakya panchangas. — Wikipedia: Chandravakyas

• 19th-century reform:

  • By the mid-1800s, traditional almanacs were misplacing stars and predicting eclipses that did not happen.
  • In Madras, Venkatakrishna Raya and Chinthamani Ragoonathachary (an astronomer at the Madras Observatory, 1822–1880) proposed a Drigganita panchang, as Chatre and Khetkar did in Bombay.
  • After a debate at the Sankara Mutt in Kumbakonam, the Mutt head issued a srimugam in 1877, and a drik almanac was published as the "Sri Kanchi Math almanac".

  — Wikipedia: Drigganita

• Drik Panchang's view (a vendor that favours drik): vakya rules were once updated but "have not been updated for centuries". Its claims include:

  • Discrepancies can reach up to 12 hours.
  • Many local Tamil Nadu calendars follow Vakyam, so the site offers a Vakyam mode.

  — drikpanchang.com

• Community view: Vakyam is better for anushtanam (ritual) and Thirukanitham for prediction. — SriPedia/Oppiliappan list archive (forum; not authoritative)

• Even drik calculators differ by 2–5 minutes on tithi end times, because of ayanamsa choice and sunrise conventions. — dekhopanchang accuracy page (via search summary)

• Example of divergence: Thirunallar temple's Sani Peyarchi (Saturn into Capricorn) was celebrated on 27 Dec 2020 at 05:22. — Karaikal district administration Computed (drik, sidereal) tables put Saturn's entry into Capricorn on 24 Jan 2020, about 11 months earlier. — vedicmarga.com; Daily Mirror LK

#Inferences

• The Thirunallar date most likely follows the Vakya almanac. This is widely said but I did not find a source that states it. If confirmed, it is a vivid "same sky, two calendars" example.
• Showing both is feasible. Drik is computed from a modern ephemeris. Vakya needs either a port of the Vakyakarana algorithms (the 1962 critical edition has an English translation and tables) or a licence to data from a commercial Vakya panchangam publisher. A middle path: compute drik, and show the published vakya dates for key yearly events (Peyarchis, Tamil New Year, festival days) with sources.

#Gaps

• No source confirmed which panchangam specific Tamil temples follow.
• I found no published, quantified study of Vakya vs Drik errors per element (tithi, nakshatra, planetary ingress).
• I could not confirm whether any open-source code implements the Vakyakarana.

#5. Dating evidence vs legend (Siddhars, Pulippani, Bogar, Agastya Nadi; Telugu/Kannada sage-astrologers before 1100 CE)

#Takeaway

Treat traditional antiquity for the Siddhar astrology corpus as legend. The texts survive in 19th–20th-century prints. The 18-Siddhar category itself may be late medieval. Scholarly dates exist only for a few figures, chiefly Tirumular, and even these range from the 6th to the 12th century. By contrast, the Kerala lineage (Haridatta 683, Sankaranarayana 869) and Kannada's Jatakatilaka (1049) are datable history.

#Cited Findings

• Tirumular:

  • Zvelebil dated him to the late 6th/early 7th century in one work and the 7th century in Poets of the Powers.
  • S. Vaiyapuripillai argued for the early 8th century.
  • Dominic Goodall argues the Tirumantiram cannot be earlier than the 11th–12th century.
  • Others posit an ancient core with interpolations.

  — Indology list; Wikipedia: Tirumular (via search summary)

• One essay argues that the term "Siddhar" as a group is missing from the Tamil nikandu lexicons, which would place the cult's formation after the 13th–14th centuries. Another source has Siddhars such as Civavakkiyar using colloquial language from the 12th century on. Both are lower-quality sources. — hinduwebsite: Chronology and History of Siddhas (via search summary)

• Wikipedia's claim that Siddhar ideas date to the "First Sangam period" rests on devotional and secondary sources. — Wikipedia: Siddhar

• Bogar placed in the 3rd–5th century CE: popular magazine only, with no scholarly backing. — Sanskriti Magazine

• Agastya Nadi / Vaitheeswaran Koil:

  • Authorship by Agastya is tradition [LEGEND].
  • The story that the leaves were stored at the Saraswati Mahal, Thanjavur and auctioned under British rule is a secondary account [UNVERIFIED].
  • The Saraswati Mahal collections began under the Nayaks (1535–1675) and grew under Serfoji II (1798–1832).
  • South Indian palm-leaf manuscripts are rarely more than 300–400 years old.

  — Vaitheeswaran Koil; Brill, Aspects of Manuscript Culture in South India (via search summary)

• The Pancha Pakshi attribution to Agastya is described as "legendary". The surviving manuscripts are in Telugu and Grantha scripts at Thanjavur, and the printed editions date from 1863 on. — Wikipedia: Pancha Pakshi Shastra; archive.org 1863

• The modern "Dr. U. S. Pulippani" (Sundara Varadachary) who wrote the 1993 English Pancha Pakshi book is a 20th-century author using a Siddhar pen name. The site should not confuse him with the Siddhar. — archive.org 1993 text

• Kannada [HISTORY]: Jatakatilaka by Shridharacharya (1049 CE) is the first astrology work in Kannada. Details:

  • It was written at Naragunda under the Chalukya king Someshvara I (Ahavamalla, 1042–1068).
  • It is a campu (mixed prose and verse) in 24 chapters, covering birth star, longevity and infant mortality.
  • It draws heavily on Varahamihira's Brihajjataka and Laghujataka and on Kalyanavarma's Saravali.
  • S. N. Krishna Jois published a critical edition (Mysore University, 1959).

  — shastriyakannada.org; Jaina Bibliography

• Kerala [HISTORY]: Haridatta (683 CE, traditional date tied to the Saka-444 correction epoch) and Shankaranarayana (869 CE). — Wikipedia: Katapayadi; Wikipedia: Haridatta

• Vararuci is a "legendary figure", and his 4th-century date rests on legend [LEGEND]. — Wikipedia: Chandravakyas

#Inferences

• Suggested labelling for the site:
  • "Attributed to Agastya/Bogar/Pulippani (traditional)" vs "Earliest surviving print: 1863".
  • "Haridatta, 683 CE (traditional date; earliest dated katapayadi user)".
  • "Shridharacharya, 1049 CE (historical)".
• The genuinely 1,000+-year-old, documented South Indian lineage is the Kerala astronomers, not the Tamil Siddhars. The Siddhar materials are culturally rich but textually late.

#Gaps

• No Telugu sage-astrologer before 1100 CE was documented in the sources I reached. Pavuluri Mallana's 11th-century Ganitasarasangrahamu (mathematics) is a lead I did not verify.
• I could not access Zvelebil's Poets of the Powers or Companion Studies, or R. Venkatraman's A History of the Tamil Siddha Cult (1990), for dates of the full 18.
• The authorship and date of the Pulippani and Bogar works are unstudied in the sources I found.

#6. Feature ideas for an astrology website

#Takeaway

The most distinctive and implementable features are a Pancha Pakshi daily-bird clock, a Katapayadi playground, and a Vakya-vs-Drik "two calendars" comparison. Each should carry clear legend-vs-history labels and links to PD scans on archive.org.

#Cited Findings

• Pancha Pakshi needs only the birth nakshatra, the paksha, and local sunrise and sunset to produce 10 daily slots, with 5 yamas each for day and night. — Biorhythms of Natal Moon
• Drik Panchang already offers a Thirukanitham/Vakyam toggle, so there is precedent and user demand. — drikpanchang.com
• Katapayadi has fun, verifiable outputs: melakarta raga numbers, the Kali-day dates in verse, and pi in the Karanapaddhati. — Wikipedia: Katapayadi
• PD Tamil source scans can be linked directly: 1863 pacapacicstiramm00akas, 1867 dli.rmrl.007550, 1922 gc-sh3-0003. — archive.org (see §1)

#Inferences

• "Your bird today"
  • Show the birth bird (with a Tamil name and its element) and a 24-hour ring of the 10 yamas, coloured by activity.
  • Highlight Ruling and Eating windows and flag the bird's padu (death) days.
  • Add a toggle for "tradition variant", and cite the source table for each slot.
• Katapayadi playground
  • Encode a name or date into a number and decode a number into a mnemonic word.
  • Include a melakarta raga finder, and a Chandravakya decoder against the modern Moon.
• "Two calendars" view
  • Show today's tithi, nakshatra and Peyarchi dates under Vakyam vs Thirukanitham.
  • Include a timeline explainer (Parahita 683 → Vakyakarana c. 1282 → Drigganita c. 1430 → Madras 1877).
• Siddhar lineage explorer
  • Interactive cards for each of the variant 18 lists, with "attributed works" and "earliest surviving edition" pulled from archive.org metadata.
  • A Pulippani verse of the day: a paraphrase in English, a link to the TVA scan, and the Bogar-lineage refrain explained.
• Prashna with five birds
  • A horary feature that uses the name-vowel bird when the birth star is unknown. This first needs the vowel table decoded from the 1863 print.
• Disclaimers: add "no scientific validation" text. Never present the famous-death examples as evidence.

#Gaps

• I did not check the licensing of modern Tamil commentary editions, which would matter for reusing commentary text. Only the 19th-century prints are safely PD.