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.

2037-03-26astronomy score per night — click a bar for that night2037-04-24

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-03-26 Thu	—	unknown	—	89.7° 12:50	8.39	73%	95.5°
2037-03-27 Fri	—	unknown	—	89.8° 12:45	8.34	83%	106.8°
2037-03-28 Sat	—	unknown	—	89.7° 12:40	8.28	91%	117.8°
2037-03-29 Sun	—	unknown	—	89.5° 13:35	8.23	97%	127.8°
2037-03-30 Mon	—	unknown	—	89.6° 13:35	8.17	100%	136.0°
2037-03-31 Tue	—	unknown	—	89.7° 13:30	8.12	99%	140.9°
2037-04-01 Wed	—	unknown	—	89.8° 13:25	8.06	96%	141.2°
2037-04-02 Thu	—	unknown	—	89.7° 13:20	8.01	91%	137.2°
2037-04-03 Fri	—	unknown	—	89.5° 13:15	7.95	84%	130.2°
2037-04-04 Sat	—	unknown	—	89.6° 13:15	7.9	75%	121.5°
2037-04-05 Sun	—	unknown	—	89.8° 13:10	7.84	65%	112.2°
2037-04-06 Mon	—	unknown	—	89.7° 13:05	7.79	55%	102.6°
2037-04-07 Tue	—	unknown	—	89.6° 13:00	7.73	46%	93.0°
2037-04-08 Wed	—	unknown	—	89.5° 13:00	7.67	36%	83.6°
2037-04-09 Thu	—	unknown	—	89.7° 12:55	7.62	27%	74.4°
2037-04-10 Fri	—	unknown	—	89.8° 12:50	7.56	19%	65.5°
2037-04-11 Sat	—	unknown	—	89.7° 12:45	7.5	12%	57.2°
2037-04-12 Sun	—	unknown	—	89.6° 12:40	7.45	7%	49.7°
2037-04-13 Mon	—	unknown	—	89.6° 12:40	7.39	3%	43.6°
2037-04-14 Tue	—	unknown	—	89.7° 12:35	7.33	1%	39.5°
2037-04-15 Wed	—	unknown	—	89.8° 12:30	7.27	0%	38.4°
2037-04-16 Thu	—	unknown	—	89.7° 12:25	7.22	2%	40.5°
2037-04-17 Fri	—	unknown	—	89.5° 12:20	7.16	5%	45.5°
2037-04-18 Sat	—	unknown	—	89.6° 12:20	7.1	11%	52.8°
2037-04-19 Sun	—	unknown	—	89.8° 12:15	7.04	18%	61.5°
2037-04-20 Mon	—	unknown	—	89.8° 12:10	6.98	27%	71.2°
2037-04-21 Tue	—	unknown	—	89.6° 12:05	6.93	37%	81.6°
2037-04-22 Wed	—	unknown	—	89.7° 12:00	6.87	48%	92.3°
2037-04-23 Thu	—	unknown	—	89.8° 11:55	6.81	59%	103.2°
2037-04-24 Fri	—	unknown	—	89.7° 11:50	6.75	70%	114.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-03-26&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.