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: 03-21 (30), 03-10 (29), 03-22 (28), 03-23 (27), 03-24 (25) — by astronomy; check the weather when the night is within four days.

2030-03-10astronomy score per night — click a bar for that night2030-04-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2030-03-28 Thu	19	—	unknown	20:20–20:55 (good, 0.58 h)	42.9° 17:35	8.3	24%	129.2°
2030-03-29 Fri	17	—	unknown	20:20–20:50 (good, 0.5 h)	42.9° 17:30	8.24	16%	118.4°
2030-03-30 Sat	15	—	unknown	20:20–20:45 (good, 0.42 h)	42.9° 17:25	8.19	9%	107.4°
2030-03-31 Sun	12	—	unknown	21:25–21:40 (good, 0.25 h)	42.9° 18:20	8.14	4%	96.3°
2030-04-01 Mon	11	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:20	8.08	1%	85.3°
2030-04-02 Tue	10	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:15	8.03	0%	74.5°
2030-04-03 Wed	8	—	unknown	21:25–21:30 (good, 0.08 h)	42.9° 18:10	7.97	1%	64.1°
2030-04-04 Thu	6	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.91	4%	54.1°
2030-04-05 Fri	5	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.86	8%	44.8°
2030-04-06 Sat	4	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.8	14%	36.7°
2030-04-07 Sun	3	—	unknown	21:35–21:45 (marginal, 0.17 h)	42.9° 17:55	7.75	21%	30.6°
2030-04-08 Mon	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.69	29%	28.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-03-10&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.