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.

Best nights for Great Orion Nebula: 04-02 (8), 04-03 (7), 04-04 (6), 04-05 (5), 04-06 (4) — by astronomy; check the weather when the night is within four days.

2045-04-02astronomy score per night — click a bar for that night2045-05-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-02 Sun	8	—	unknown	20:50–22:05 (marginal, 1.25 h)	42.9° 18:15	8.01	98%	118.2°
2045-04-03 Mon	7	—	unknown	20:55–22:00 (marginal, 1.08 h)	42.9° 18:10	7.95	94%	128.4°
2045-04-04 Tue	6	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.89	88%	137.1°
2045-04-05 Wed	5	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.84	81%	143.4°
2045-04-06 Thu	4	—	unknown	21:30–21:45 (marginal, 0.25 h)	42.9° 17:55	7.78	72%	146.4°
2045-04-07 Fri	3	—	unknown	21:00–21:15 (marginal, 0.25 h)	42.9° 17:55	7.73	63%	145.6°
2045-04-08 Sat	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.67	54%	141.3°
2045-04-09 Sun	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.61	44%	134.6°
2045-04-10 Mon	1	—	unknown	—	42.9° 17:40	7.56	35%	126.5°
2045-04-11 Tue	1	—	unknown	—	42.9° 17:40	7.5	26%	117.5°
2045-04-12 Wed	1	—	unknown	—	42.9° 17:35	7.44	18%	107.9°
2045-04-13 Thu	1	—	unknown	—	42.9° 17:30	7.39	12%	97.8°
2045-04-14 Fri	1	—	unknown	—	42.9° 17:25	7.33	6%	87.5°
2045-04-15 Sat	0	—	unknown	—	42.9° 17:20	7.27	2%	77.0°
2045-04-16 Sun	0	—	unknown	—	42.9° 17:20	7.21	0%	66.4°
2045-04-17 Mon	0	—	unknown	—	42.9° 17:15	7.15	1%	56.1°
2045-04-18 Tue	0	—	unknown	—	42.9° 17:10	7.1	3%	46.6°
2045-04-19 Wed	0	—	unknown	—	42.9° 17:05	7.04	8%	38.7°
2045-04-20 Thu	0	—	unknown	—	42.9° 17:00	6.98	15%	34.0°
2045-04-21 Fri	0	—	unknown	—	42.9° 17:00	6.92	24%	33.9°
2045-04-22 Sat	0	—	unknown	—	42.9° 16:55	6.86	35%	38.6°
2045-04-23 Sun	0	—	unknown	—	42.9° 16:50	6.81	46%	46.8°
2045-04-24 Mon	0	—	unknown	—	42.9° 16:45	6.75	57%	56.8°
2045-04-25 Tue	0	—	unknown	—	42.9° 16:45	6.69	68%	67.9°
2045-04-26 Wed	0	—	unknown	—	42.9° 16:40	6.63	78%	79.5°
2045-04-27 Thu	0	—	unknown	—	42.9° 16:35	6.57	87%	91.3°
2045-04-28 Fri	0	—	unknown	—	42.9° 16:30	6.51	94%	102.9°
2045-04-29 Sat	0	—	unknown	—	42.9° 16:25	6.46	98%	114.1°
2045-04-30 Sun	0	—	unknown	—	42.9° 16:25	6.4	100%	124.7°
2045-05-01 Mon	0	—	unknown	—	42.9° 16:20	6.34	99%	134.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-02&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.