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.

2044-04-20astronomy score per night — click a bar for that night2044-05-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-04-20 Wed	—	unknown	—	42.9° 17:00	6.97	46%	127.4°
2044-04-21 Thu	—	unknown	—	42.9° 16:55	6.91	36%	118.2°
2044-04-22 Fri	—	unknown	—	42.9° 16:55	6.85	27%	108.2°
2044-04-23 Sat	—	unknown	—	42.9° 16:50	6.79	18%	97.6°
2044-04-24 Sun	—	unknown	—	42.9° 16:45	6.73	11%	86.5°
2044-04-25 Mon	—	unknown	—	42.9° 16:40	6.67	5%	75.1°
2044-04-26 Tue	—	unknown	—	42.9° 16:40	6.62	1%	63.7°
2044-04-27 Wed	—	unknown	—	42.9° 16:35	6.56	0%	52.8°
2044-04-28 Thu	—	unknown	—	42.9° 16:30	6.5	2%	43.1°
2044-04-29 Fri	—	unknown	—	42.9° 16:25	6.44	6%	36.1°
2044-04-30 Sat	—	unknown	—	42.9° 16:20	6.38	14%	33.8°
2044-05-01 Sun	—	unknown	—	42.9° 16:20	6.33	23%	36.8°
2044-05-02 Mon	—	unknown	—	42.9° 16:15	6.27	33%	44.0°
2044-05-03 Tue	—	unknown	—	42.9° 16:10	6.21	44%	53.4°
2044-05-04 Wed	—	unknown	—	42.9° 16:05	6.15	56%	63.9°
2044-05-05 Thu	—	unknown	—	42.9° 16:00	6.1	66%	74.8°
2044-05-06 Fri	—	unknown	—	42.9° 16:00	6.04	76%	85.7°
2044-05-07 Sat	—	unknown	—	42.9° 15:55	5.98	84%	96.5°
2044-05-08 Sun	—	unknown	—	42.9° 15:50	5.93	91%	107.0°
2044-05-09 Mon	—	unknown	—	42.9° 15:45	5.87	96%	117.1°
2044-05-10 Tue	—	unknown	—	42.9° 15:45	5.81	99%	126.4°
2044-05-11 Wed	—	unknown	—	42.9° 15:40	5.76	100%	134.7°
2044-05-12 Thu	—	unknown	—	42.9° 15:35	5.7	99%	141.4°
2044-05-13 Fri	—	unknown	—	42.9° 15:30	5.65	96%	145.4°
2044-05-14 Sat	—	unknown	—	42.9° 15:25	5.6	92%	146.1°
2044-05-15 Sun	—	unknown	—	42.9° 15:25	5.54	86%	143.3°
2044-05-16 Mon	—	unknown	—	42.9° 15:20	5.49	79%	137.7°
2044-05-17 Tue	—	unknown	—	42.9° 15:15	5.44	71%	130.1°
2044-05-18 Wed	—	unknown	—	42.9° 15:10	5.39	62%	121.4°
2044-05-19 Thu	—	unknown	—	42.9° 15:05	5.34	52%	111.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-04-20&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.