{"id":"vidhyamitra:day:2021-09-13:en","page_class":"VM-1-day","url":"https://vidhyamitra.com/day/2021-09-13","language":{"target_lang":"en","base_lang":"en","quality_tier":"canonical"},"data":{"date":"2021-09-13","date_display":"September 13, 2021 CE","panchanga":{"method":"Sūrya Siddhānta + Bhāskara-II iterative manda + Kerala-school (Mādhava-Nīlakaṇṭha) evection + variation + annual equation","engine_version":"2.0 (Kerala-school enhanced)","accuracy_note":"Sub-degree on Moon at any Kali-Yuga date (~2-5° residual max)","tradition_chain":"Āryabhaṭa(499) → Brahmagupta(628) → Bhāskara II(1150) → Mādhava(~1400) → Parameśvara(1430) → Nīlakaṇṭha(1501) → this","input":{"year":2021,"month":9,"day":13,"hour":6,"minute":30,"second":0,"calendar":"gregorian"},"julian_day":2459470.770833,"kali_year":5123,"ahargana":1871005.2708,"sun":{"sidereal_longitude":145.5557,"rashi":5,"rashi_name":"Siṃha"},"moon":{"sidereal_longitude":223.5642,"rashi":8,"rashi_name":"Vṛścika"},"tithi":{"number":7,"name":"Saptamī","paksha":"Śukla","full_name":"Śukla Saptamī","elongation_degrees":78.0085,"elapsed_within_tithi_degrees":6.0085},"nakshatra":{"number":17,"name":"Anurādhā","pada":4,"moon_longitude":223.5642,"elapsed_within_degrees":10.2309},"yoga":{"number":1,"name":"Viṣkambha","sum_longitude":9.12},"karana":{"half_tithi_index":13,"name":"Vaṇija"},"vara":{"number":3,"name":"Somavāra (Monday)"}},"sky":{"method":"Sūrya-Siddhāntic Bhāskara-II 4-step iteration with atan2-based śīghra + varying peripheries + lunar latitude","engine_version":"3.0 (Pūrṇa — complete SS implementation)","tradition_sources":"Āryabhaṭīya 499 CE → SS Ch.1-5 Burgess 1860 → Siddhānta-Śiromaṇi Bhāskara II 1150 → Tantrasaṅgraha Nīlakaṇṭha 1501","input":{"year":2021,"month":9,"day":13,"hour":6,"minute":30,"calendar":"gregorian"},"julian_day":2459470.770833,"ahargana":1871005.2708,"kali_year":5123,"ayanamsa_lahiri":24.1561,"grahas":{"sun":{"sidereal_longitude":146.331188,"rashi":{"number":5,"name":"Siṃha"},"nakshatra":{"number":11,"name":"Pūrva Phalgunī","pada":4},"retrograde":false},"moon":{"sidereal_longitude":225.60398799999996,"rashi":{"number":8,"name":"Vṛścika"},"nakshatra":{"number":17,"name":"Anurādhā","pada":4},"retrograde":false,"latitude":0.1234},"mars":{"sidereal_longitude":154.24038799999994,"rashi":{"number":6,"name":"Kanyā"},"nakshatra":{"number":12,"name":"Uttara Phalgunī","pada":3},"retrograde":false},"mercury":{"sidereal_longitude":172.72588799999994,"rashi":{"number":6,"name":"Kanyā"},"nakshatra":{"number":13,"name":"Hasta","pada":4},"retrograde":false},"jupiter":{"sidereal_longitude":300.1056880000001,"rashi":{"number":11,"name":"Kumbha"},"nakshatra":{"number":23,"name":"Dhaniṣṭhā","pada":3},"retrograde":true},"venus":{"sidereal_longitude":188.077588,"rashi":{"number":7,"name":"Tulā"},"nakshatra":{"number":15,"name":"Svātī","pada":1},"retrograde":false},"saturn":{"sidereal_longitude":283.38988800000004,"rashi":{"number":10,"name":"Makara"},"nakshatra":{"number":22,"name":"Śravaṇa","pada":2},"retrograde":true},"rahu":{"sidereal_longitude":45.1368,"rashi":{"number":2,"name":"Vṛṣabha"},"nakshatra":{"number":4,"name":"Rohiṇī","pada":2},"retrograde":false},"ketu":{"sidereal_longitude":225.1368,"rashi":{"number":8,"name":"Vṛścika"},"nakshatra":{"number":17,"name":"Anurādhā","pada":4},"retrograde":false}},"panchang":{"method":"Sūrya Siddhānta + Bhāskara-II iterative manda + Kerala-school (Mādhava-Nīlakaṇṭha) evection + variation + annual equation","engine_version":"2.0 (Kerala-school enhanced)","accuracy_note":"Sub-degree on Moon at any Kali-Yuga date (~2-5° residual max)","tradition_chain":"Āryabhaṭa(499) → Brahmagupta(628) → Bhāskara II(1150) → Mādhava(~1400) → Parameśvara(1430) → Nīlakaṇṭha(1501) → this","input":{"year":2021,"month":9,"day":13,"hour":6,"minute":30,"second":0,"calendar":"gregorian"},"julian_day":2459470.770833,"kali_year":5123,"ahargana":1871005.2708,"sun":{"sidereal_longitude":145.5557,"rashi":5,"rashi_name":"Siṃha"},"moon":{"sidereal_longitude":223.5642,"rashi":8,"rashi_name":"Vṛścika"},"tithi":{"number":7,"name":"Saptamī","paksha":"Śukla","full_name":"Śukla Saptamī","elongation_degrees":78.0085,"elapsed_within_tithi_degrees":6.0085},"nakshatra":{"number":17,"name":"Anurādhā","pada":4,"moon_longitude":223.5642,"elapsed_within_degrees":10.2309},"yoga":{"number":1,"name":"Viṣkambha","sum_longitude":9.12},"karana":{"half_tithi_index":13,"name":"Vaṇija"},"vara":{"number":3,"name":"Somavāra (Monday)"}},"eclipse_current":{"solar":{"type":"solar","occurs":false,"moon_latitude":0.123,"elongation":78.009},"lunar":{"type":"lunar","occurs":false,"moon_latitude":0.123,"opposition_distance":101.991}},"eclipse_window_40days":[]},"calendars":{"vikram_samvat":2078,"vikram_samvatsara":"Ānanda","saka_samvat":1943,"saka_samvatsara":"Plava","bengali_samvat":1428,"malayalam_era":1197,"nanakshahi_year":552,"lunar_month":"Bhādrapada","lunar_month_paksha_full":"Bhādrapada Śukla Pakṣa","solar_month":"Siṃha (Āvaṇi)","ritu":"Varṣā (Monsoon)","display_summary":"Bhādrapada Śukla Saptamī · Vikram 2078 Ānanda · Śaka 1943 Plava"},"festivals":[{"id":"simha-sankranti","name":"Siṁha Saṅkrānti","name_sanskrit":"सिंह सङ्क्रान्ति","tradition":"Pan-Hindu","significance":"Sun enters Leo.","vrata":false,"detection":{"sun_rashi":"Siṃha"},"precedence":5}],"todays_walk":{"walk":{"id":"chandra-walk","name":"Candra Walk","name_sanskrit":"चन्द्र यात्रा","type":"graha","description":"Manas-control + BG 6.5-7.","step_count":5,"url":"/walk/chandra-walk"},"reason":"Somavāra (Monday) — its presiding graha's walk."},"cosmic_resonances":[]},"validity":{"eternal":false,"valid_from":"2021-09-13T00:00:00Z"},"liturgical":{"opening":"जय श्री कृष्ण","closing":"ॐ तत् सत्","attribution":"Computed by Vidhyamitra Sūrya-Siddhānta substrate; Vidhyamitra substrate"},"seo":{"title":"Pañchāṅga September 13, 2021 CE · Vidhyamitra","description":"Vedic pañchāṅga for September 13, 2021 CE: Śukla Saptamī · Anurādhā.","schema_org_type":"Article","canonical":"https://vidhyamitra.com/day/2021-09-13","hreflang_alternates":{"en":"https://vidhyamitra.com/day/2021-09-13","sa":"https://sa.vidhyamitra.com/day/2021-09-13","hi":"https://hi.vidhyamitra.com/day/2021-09-13","x-default":"https://vidhyamitra.com/day/2021-09-13"}},"provenance":[{"pillar":"BOB-History","pillar_version":"2.12.0","method":"Sūrya-Siddhānta first-principles + Bhāskara II + Kerala-school (Mādhava-Nīlakaṇṭha) corrections","retrieved_at":"2026-05-14T08:33:12.181Z","verification":{"type":"multi-marker","confidence":"canonical"}}],"meta":{"generated_at":"2026-05-14T08:33:12.181Z","pillar_versions":{"BOB-History":"Pūrṇa"}}}