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: 02-26 (70), 02-25 (69), 02-27 (69), 02-28 (67), 02-24 (66) — by astronomy; check the weather when the night is within four days.

2035-02-21astronomy score per night — click a bar for that night2035-03-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-02-21 Wed	27	—	unknown	19:35–23:15 (marginal, 3.67 h)	42.9° 19:50	10.01	100%	67.1°
2035-02-22 Thu	37	—	unknown	19:40–20:45 (good, 1.08 h)	42.9° 19:50	9.96	100%	79.6°
2035-02-23 Fri	49	—	unknown	19:40–22:20 (good, 2.67 h)	42.9° 19:45	9.92	97%	92.0°
2035-02-24 Sat	66	—	unknown	19:40–22:40 (good, 3.0 h)	42.9° 19:40	9.88	92%	104.0°
2035-02-25 Sun	69	—	unknown	19:40–22:45 (good, 3.08 h)	42.9° 19:35	9.83	86%	115.6°
2035-02-26 Mon	70	—	unknown	19:40–22:45 (good, 3.08 h)	42.9° 19:30	9.79	79%	126.6°
2035-02-27 Tue	69	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.75	70%	136.9°
2035-02-28 Wed	67	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.7	61%	146.0°
2035-03-01 Thu	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.66	52%	153.2°
2035-03-02 Fri	63	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:15	9.61	42%	156.5°
2035-03-03 Sat	62	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:15	9.56	33%	154.5°
2035-03-04 Sun	60	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.52	24%	148.1°
2035-03-05 Mon	58	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.47	17%	139.1°
2035-03-06 Tue	57	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.42	10%	128.8°
2035-03-07 Wed	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.38	5%	117.5°
2035-03-08 Thu	53	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:55	9.33	1%	105.7°
2035-03-09 Fri	51	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.28	0%	93.4°
2035-03-10 Sat	50	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.23	1%	80.9°
2035-03-11 Sun	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.18	5%	68.2°
2035-03-12 Mon	43	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.13	11%	55.7°
2035-03-13 Tue	37	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:35	9.09	19%	43.6°
2035-03-14 Wed	29	—	unknown	20:00–21:30 (good, 1.5 h)	42.9° 18:30	9.04	29%	32.8°
2035-03-15 Thu	22	—	unknown	20:05–21:05 (good, 1.0 h)	42.9° 18:25	8.99	40%	25.2°
2035-03-16 Fri	15	—	unknown	20:05–22:05 (marginal, 2.0 h)	42.9° 18:20	8.94	51%	23.9°
2035-03-17 Sat	11	—	unknown	20:05–21:45 (marginal, 1.67 h)	42.9° 18:20	8.88	62%	29.7°
2035-03-18 Sun	9	—	unknown	20:05–21:35 (marginal, 1.5 h)	42.9° 18:15	8.83	73%	39.5°
2035-03-19 Mon	9	—	unknown	20:05–21:30 (marginal, 1.42 h)	42.9° 18:10	8.78	82%	51.0°
2035-03-20 Tue	9	—	unknown	20:10–21:30 (marginal, 1.33 h)	42.9° 18:05	8.73	90%	63.1°
2035-03-21 Wed	11	—	unknown	20:10–21:35 (marginal, 1.42 h)	42.9° 18:00	8.68	96%	75.3°
2035-03-22 Thu	14	—	unknown	20:10–21:40 (marginal, 1.5 h)	42.9° 18:00	8.63	99%	87.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-02-21&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.