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 (69), 02-27 (69), 02-28 (66), 03-01 (65), 03-02 (63) — by astronomy; check the weather when the night is within four days.

2030-02-26astronomy score per night — click a bar for that night2030-03-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-02-26 Tue	69	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.78	30%	150.8°
2030-02-27 Wed	69	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.74	20%	145.4°
2030-02-28 Thu	66	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.69	12%	136.8°
2030-03-01 Fri	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.65	6%	126.5°
2030-03-02 Sat	63	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:15	9.6	2%	115.5°
2030-03-03 Sun	61	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.55	0%	104.3°
2030-03-04 Mon	60	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:10	9.51	1%	93.1°
2030-03-05 Tue	58	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.46	3%	82.1°
2030-03-06 Wed	55	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.41	7%	71.3°
2030-03-07 Thu	49	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.37	13%	61.0°
2030-03-08 Fri	43	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:50	9.32	20%	51.2°
2030-03-09 Sat	36	—	unknown	19:55–21:50 (good, 1.92 h)	42.9° 18:50	9.27	28%	42.3°
2030-03-10 Sun	29	—	unknown	19:55–21:35 (good, 1.67 h)	42.9° 18:45	9.22	37%	34.7°
2030-03-11 Mon	21	—	unknown	20:00–22:30 (marginal, 2.5 h)	42.9° 18:40	9.17	46%	29.7°
2030-03-12 Tue	15	—	unknown	20:00–22:15 (marginal, 2.25 h)	42.9° 18:35	9.12	56%	28.5°
2030-03-13 Wed	12	—	unknown	20:00–22:00 (marginal, 2.0 h)	42.9° 18:30	9.07	65%	31.9°
2030-03-14 Thu	10	—	unknown	20:00–21:45 (marginal, 1.75 h)	42.9° 18:30	9.02	74%	38.8°
2030-03-15 Fri	9	—	unknown	20:05–21:40 (marginal, 1.58 h)	42.9° 18:25	8.97	83%	48.1°
2030-03-16 Sat	10	—	unknown	20:05–21:40 (marginal, 1.58 h)	42.9° 18:20	8.92	90%	58.8°
2030-03-17 Sun	13	—	unknown	20:05–21:45 (marginal, 1.67 h)	42.9° 18:15	8.87	96%	70.4°
2030-03-18 Mon	17	—	unknown	20:05–21:55 (marginal, 1.83 h)	42.9° 18:15	8.82	99%	82.8°
2030-03-19 Tue	20	—	unknown	20:10–21:00 (good, 0.83 h)	42.9° 18:10	8.77	100%	95.5°
2030-03-20 Wed	24	—	unknown	20:10–21:05 (good, 0.92 h)	42.9° 18:05	8.72	98%	108.3°
2030-03-21 Thu	30	—	unknown	20:10–21:10 (good, 1.0 h)	42.9° 18:00	8.67	93%	120.9°
2030-03-22 Fri	28	—	unknown	20:10–21:15 (good, 1.08 h)	42.9° 17:55	8.62	86%	132.7°
2030-03-23 Sat	27	—	unknown	20:15–21:10 (good, 0.92 h)	42.9° 17:55	8.56	77%	142.9°
2030-03-24 Sun	25	—	unknown	20:15–21:10 (good, 0.92 h)	42.9° 17:50	8.51	66%	150.0°
2030-03-25 Mon	24	—	unknown	20:15–21:05 (good, 0.83 h)	42.9° 17:45	8.46	55%	151.6°
2030-03-26 Tue	22	—	unknown	20:15–21:00 (good, 0.75 h)	42.9° 17:40	8.41	44%	147.2°
2030-03-27 Wed	20	—	unknown	20:20–20:55 (good, 0.58 h)	42.9° 17:35	8.35	34%	139.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-02-26&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.