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.

2030-12-14astronomy score per night — click a bar for that night2031-01-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-01-02 Thu	54	—	unknown	19:45–03:00 (marginal, 7.25 h)	42.9° 23:10	11.44	72%	52.3°
2031-01-03 Fri	37	—	unknown	20:00–02:45 (marginal, 6.75 h)	42.9° 23:05	11.43	81%	42.9°
2031-01-04 Sat	23	—	unknown	21:25–02:25 (marginal, 5.0 h)	42.9° 23:00	11.42	88%	34.8°
2031-01-05 Sun	14	—	unknown	01:40–01:45 (marginal, 0.08 h)	42.9° 22:55	11.4	93%	29.1°
2031-01-06 Mon	11	—	unknown	—	42.9° 22:55	11.39	97%	27.1°
2031-01-07 Tue	11	—	unknown	—	42.9° 22:50	11.38	99%	29.8°
2031-01-08 Wed	17	—	unknown	19:40–21:45 (marginal, 2.08 h)	42.9° 22:45	11.36	100%	36.1°
2031-01-09 Thu	28	—	unknown	19:10–00:35 (marginal, 5.42 h)	42.9° 22:40	11.34	99%	44.6°
2031-01-10 Fri	44	—	unknown	18:50–01:45 (marginal, 6.92 h)	42.9° 22:35	11.33	96%	54.2°
2031-01-11 Sat	82	—	unknown	19:20–21:35 (good, 2.25 h)	42.9° 22:35	11.31	91%	64.7°
2031-01-12 Sun	86	—	unknown	19:15–00:05 (good, 4.83 h)	42.9° 22:30	11.29	84%	75.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-12-14&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.