Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

2028-03-21astronomy score per night — click a bar for that night2028-04-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-03-21 Tue	—	unknown	—	89.5° 13:05	8.64	16%	74.6°
2028-03-22 Wed	—	unknown	—	89.6° 13:05	8.59	9%	64.4°
2028-03-23 Thu	—	unknown	—	89.7° 13:00	8.54	5%	54.5°
2028-03-24 Fri	—	unknown	—	89.7° 12:55	8.49	2%	45.2°
2028-03-25 Sat	—	unknown	—	89.6° 12:50	8.43	0%	37.0°
2028-03-26 Sun	—	unknown	—	89.5° 13:50	8.38	1%	30.8°
2028-03-27 Mon	—	unknown	—	89.6° 13:45	8.33	3%	28.3°
2028-03-28 Tue	—	unknown	—	89.7° 13:40	8.27	7%	30.5°
2028-03-29 Wed	—	unknown	—	89.7° 13:35	8.22	13%	36.8°
2028-03-30 Thu	—	unknown	—	89.5° 13:30	8.16	21%	45.6°
2028-03-31 Fri	—	unknown	—	89.5° 13:30	8.11	30%	55.9°
2028-04-01 Sat	—	unknown	—	89.7° 13:25	8.05	40%	67.1°
2028-04-02 Sun	—	unknown	—	89.7° 13:20	8.0	51%	78.9°
2028-04-03 Mon	—	unknown	—	89.6° 13:15	7.94	63%	91.2°
2028-04-04 Tue	—	unknown	—	89.5° 13:10	7.89	73%	103.7°
2028-04-05 Wed	—	unknown	—	89.6° 13:10	7.83	83%	116.3°
2028-04-06 Thu	—	unknown	—	89.7° 13:05	7.78	91%	128.5°
2028-04-07 Fri	—	unknown	—	89.7° 13:00	7.72	97%	139.6°
2028-04-08 Sat	—	unknown	—	89.6° 12:55	7.66	100%	148.2°
2028-04-09 Sun	—	unknown	—	89.5° 12:55	7.61	100%	151.7°
2028-04-10 Mon	—	unknown	—	89.6° 12:50	7.55	97%	148.7°
2028-04-11 Tue	—	unknown	—	89.7° 12:45	7.49	92%	141.0°
2028-04-12 Wed	—	unknown	—	89.7° 12:40	7.44	85%	131.1°
2028-04-13 Thu	—	unknown	—	89.5° 12:35	7.38	76%	120.4°
2028-04-14 Fri	—	unknown	—	89.5° 12:35	7.32	67%	109.6°
2028-04-15 Sat	—	unknown	—	89.7° 12:30	7.26	57%	98.7°
2028-04-16 Sun	—	unknown	—	89.7° 12:25	7.21	48%	88.1°
2028-04-17 Mon	—	unknown	—	89.6° 12:20	7.15	38%	77.6°
2028-04-18 Tue	—	unknown	—	89.5° 12:15	7.09	29%	67.3°
2028-04-19 Wed	—	unknown	—	89.6° 12:15	7.03	21%	57.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-03-21&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.