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: 02-25 (61), 02-26 (51), 03-11 (45), 03-12 (45), 03-13 (45) — by astronomy; check the weather when the night is within four days.

2031-02-25astronomy score per night — click a bar for that night2031-03-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-02-25 Tue	61	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.83	20%	58.9°
2031-02-26 Wed	51	—	unknown	19:40–22:40 (good, 3.0 h)	42.9° 19:30	9.79	29%	48.5°
2031-02-27 Thu	40	—	unknown	19:45–22:25 (good, 2.67 h)	42.9° 19:30	9.75	38%	39.2°
2031-02-28 Fri	30	—	unknown	19:45–23:15 (marginal, 3.5 h)	42.9° 19:25	9.7	48%	31.8°
2031-03-01 Sat	22	—	unknown	19:45–23:00 (marginal, 3.25 h)	42.9° 19:20	9.66	57%	27.4°
2031-03-02 Sun	16	—	unknown	19:45–22:45 (marginal, 3.0 h)	42.9° 19:15	9.61	66%	27.4°
2031-03-03 Mon	12	—	unknown	19:50–22:25 (marginal, 2.58 h)	42.9° 19:15	9.56	75%	31.8°
2031-03-04 Tue	11	—	unknown	19:50–22:10 (marginal, 2.33 h)	42.9° 19:10	9.52	83%	39.2°
2031-03-05 Wed	12	—	unknown	19:50–22:10 (marginal, 2.33 h)	42.9° 19:05	9.47	89%	48.3°
2031-03-06 Thu	15	—	unknown	19:50–22:15 (marginal, 2.42 h)	42.9° 19:00	9.42	95%	58.5°
2031-03-07 Fri	19	—	unknown	19:55–22:25 (marginal, 2.5 h)	42.9° 18:55	9.38	98%	69.4°
2031-03-08 Sat	25	—	unknown	19:55–20:15 (good, 0.33 h)	42.9° 18:55	9.33	100%	80.8°
2031-03-09 Sun	31	—	unknown	19:55–21:35 (good, 1.67 h)	42.9° 18:50	9.28	99%	92.5°
2031-03-10 Mon	44	—	unknown	19:55–21:45 (good, 1.83 h)	42.9° 18:45	9.23	96%	104.4°
2031-03-11 Tue	45	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:40	9.18	91%	116.3°
2031-03-12 Wed	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.14	84%	127.9°
2031-03-13 Thu	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.09	75%	138.8°
2031-03-14 Fri	43	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.04	65%	147.8°
2031-03-15 Sat	40	—	unknown	20:05–21:45 (good, 1.67 h)	42.9° 18:25	8.99	54%	153.0°
2031-03-16 Sun	38	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:20	8.94	42%	151.9°
2031-03-17 Mon	38	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:20	8.89	31%	145.0°
2031-03-18 Tue	36	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:15	8.84	21%	134.9°
2031-03-19 Wed	34	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:10	8.78	13%	123.4°
2031-03-20 Thu	32	—	unknown	20:10–21:25 (good, 1.25 h)	42.9° 18:05	8.73	6%	111.2°
2031-03-21 Fri	30	—	unknown	20:10–21:20 (good, 1.17 h)	42.9° 18:00	8.68	2%	98.9°
2031-03-22 Sat	29	—	unknown	20:10–21:15 (good, 1.08 h)	42.9° 18:00	8.63	0%	86.6°
2031-03-23 Sun	28	—	unknown	20:10–21:15 (good, 1.08 h)	42.9° 17:55	8.58	1%	74.7°
2031-03-24 Mon	25	—	unknown	20:15–21:10 (good, 0.92 h)	42.9° 17:50	8.52	4%	63.1°
2031-03-25 Tue	22	—	unknown	20:15–21:05 (good, 0.83 h)	42.9° 17:45	8.47	8%	52.2°
2031-03-26 Wed	19	—	unknown	20:15–20:55 (good, 0.67 h)	42.9° 17:40	8.42	15%	42.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-02-25&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.