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: 12-17 (89), 12-18 (89), 12-19 (89), 12-20 (89), 12-21 (89) — by astronomy; check the weather when the night is within four days.

2030-12-03astronomy score per night — click a bar for that night2031-01-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-12-03 Tue	87	—	unknown	22:25–04:25 (good, 6.0 h)	42.9° 01:05	11.36	70%	81.6°
2030-12-04 Wed	83	—	unknown	00:00–04:20 (good, 4.33 h)	42.9° 01:05	11.38	78%	70.6°
2030-12-05 Thu	60	—	unknown	04:10–04:20 (good, 0.17 h)	42.9° 01:00	11.39	86%	60.0°
2030-12-06 Fri	37	—	unknown	22:00–04:40 (marginal, 6.67 h)	42.9° 00:55	11.41	92%	50.0°
2030-12-07 Sat	23	—	unknown	00:00–04:15 (marginal, 4.25 h)	42.9° 00:50	11.42	96%	40.8°
2030-12-08 Sun	14	—	unknown	03:05–03:40 (marginal, 0.58 h)	42.9° 00:45	11.43	99%	33.2°
2030-12-09 Mon	10	—	unknown	—	42.9° 00:45	11.44	100%	28.2°
2030-12-10 Tue	10	—	unknown	—	42.9° 00:40	11.45	99%	27.4°
2030-12-11 Wed	14	—	unknown	21:45–22:25 (marginal, 0.67 h)	42.9° 00:35	11.46	96%	31.1°
2030-12-12 Thu	25	—	unknown	21:10–02:00 (marginal, 4.83 h)	42.9° 00:30	11.47	92%	38.0°
2030-12-13 Fri	39	—	unknown	20:50–03:35 (marginal, 6.75 h)	42.9° 00:25	11.48	86%	46.7°
2030-12-14 Sat	63	—	unknown	21:10–21:20 (good, 0.17 h)	42.9° 00:25	11.49	79%	56.6°
2030-12-15 Sun	83	—	unknown	21:05–01:50 (good, 4.75 h)	42.9° 00:20	11.49	70%	67.1°
2030-12-16 Mon	88	—	unknown	21:00–03:05 (good, 6.08 h)	42.9° 00:15	11.5	61%	78.1°
2030-12-17 Tue	89	—	unknown	20:55–03:15 (good, 6.33 h)	42.9° 00:10	11.5	51%	89.5°
2030-12-18 Wed	89	—	unknown	20:55–03:20 (good, 6.42 h)	42.9° 00:10	11.5	40%	101.2°
2030-12-19 Thu	89	—	unknown	20:50–03:20 (good, 6.5 h)	42.9° 00:05	11.51	30%	113.2°
2030-12-20 Fri	89	—	unknown	20:45–03:20 (good, 6.58 h)	42.9° 00:00	11.51	20%	125.2°
2030-12-21 Sat	89	—	unknown	20:40–03:15 (good, 6.58 h)	42.9° 23:55	11.51	11%	136.8°
2030-12-22 Sun	89	—	unknown	20:40–03:10 (good, 6.5 h)	42.9° 23:50	11.51	5%	146.7°
2030-12-23 Mon	89	—	unknown	20:35–03:05 (good, 6.5 h)	42.9° 23:50	11.51	1%	152.5°
2030-12-24 Tue	89	—	unknown	20:30–03:05 (good, 6.58 h)	42.9° 23:45	11.5	0%	151.1°
2030-12-25 Wed	89	—	unknown	20:25–03:00 (good, 6.58 h)	42.9° 23:40	11.5	2%	143.3°
2030-12-26 Thu	89	—	unknown	20:20–02:55 (good, 6.58 h)	42.9° 23:35	11.5	7%	132.5°
2030-12-27 Fri	89	—	unknown	20:20–02:50 (good, 6.5 h)	42.9° 23:30	11.49	14%	120.6°
2030-12-28 Sat	89	—	unknown	20:20–02:45 (good, 6.42 h)	42.9° 23:30	11.48	23%	108.4°
2030-12-29 Sun	89	—	unknown	20:20–02:45 (good, 6.42 h)	42.9° 23:25	11.48	33%	96.3°
2030-12-30 Mon	88	—	unknown	20:25–02:40 (good, 6.25 h)	42.9° 23:20	11.47	44%	84.6°
2030-12-31 Tue	85	—	unknown	20:30–02:35 (good, 6.08 h)	42.9° 23:15	11.46	54%	73.3°
2031-01-01 Wed	77	—	unknown	21:55–02:30 (good, 4.58 h)	42.9° 23:15	11.45	64%	62.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-12-03&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.