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: 12-15 (89), 12-16 (89), 12-17 (89), 12-18 (89), 12-19 (89) — by astronomy; check the weather when the night is within four days.

2036-12-15astronomy score per night — click a bar for that night2037-01-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-12-15 Mon	89	—	unknown	21:05–03:35 (good, 6.5 h)	42.9° 00:20	11.49	3%	150.1°
2036-12-16 Tue	89	—	unknown	21:00–03:35 (good, 6.58 h)	42.9° 00:15	11.5	1%	154.7°
2036-12-17 Wed	89	—	unknown	20:55–03:30 (good, 6.58 h)	42.9° 00:10	11.5	0%	153.8°
2036-12-18 Thu	89	—	unknown	20:50–03:25 (good, 6.58 h)	42.9° 00:05	11.5	2%	147.9°
2036-12-19 Fri	89	—	unknown	20:50–03:20 (good, 6.5 h)	42.9° 00:00	11.51	5%	139.3°
2036-12-20 Sat	89	—	unknown	20:45–03:15 (good, 6.5 h)	42.9° 00:00	11.51	10%	129.6°
2036-12-21 Sun	89	—	unknown	20:40–03:15 (good, 6.58 h)	42.9° 23:55	11.51	16%	119.3°
2036-12-22 Mon	89	—	unknown	20:40–03:10 (good, 6.5 h)	42.9° 23:50	11.51	24%	108.8°
2036-12-23 Tue	89	—	unknown	20:40–03:05 (good, 6.42 h)	42.9° 23:45	11.5	32%	98.2°
2036-12-24 Wed	89	—	unknown	20:40–03:00 (good, 6.33 h)	42.9° 23:40	11.5	42%	87.4°
2036-12-25 Thu	88	—	unknown	20:45–02:55 (good, 6.17 h)	42.9° 23:40	11.5	51%	76.6°
2036-12-26 Fri	85	—	unknown	21:20–02:55 (good, 5.58 h)	42.9° 23:35	11.49	61%	65.6°
2036-12-27 Sat	76	—	unknown	23:45–02:50 (good, 3.08 h)	42.9° 23:30	11.49	70%	54.7°
2036-12-28 Sun	44	—	unknown	20:15–03:15 (marginal, 7.0 h)	42.9° 23:25	11.48	79%	44.0°
2036-12-29 Mon	27	—	unknown	20:50–02:55 (marginal, 6.08 h)	42.9° 23:20	11.47	87%	34.2°
2036-12-30 Tue	16	—	unknown	01:15–02:15 (marginal, 1.0 h)	42.9° 23:20	11.47	94%	26.9°
2036-12-31 Wed	10	—	unknown	—	42.9° 23:15	11.46	98%	25.2°
2037-01-01 Thu	11	—	unknown	—	42.9° 23:10	11.45	100%	30.5°
2037-01-02 Fri	21	—	unknown	19:50–23:20 (marginal, 3.5 h)	42.9° 23:05	11.44	99%	40.5°
2037-01-03 Sat	37	—	unknown	19:25–02:00 (marginal, 6.58 h)	42.9° 23:05	11.42	95%	52.5°
2037-01-04 Sun	73	—	unknown	20:20–21:15 (good, 0.92 h)	42.9° 23:00	11.41	89%	65.5°
2037-01-05 Mon	85	—	unknown	19:40–00:45 (good, 5.08 h)	42.9° 22:55	11.4	80%	78.7°
2037-01-06 Tue	88	—	unknown	19:35–01:45 (good, 6.17 h)	42.9° 22:50	11.38	70%	91.8°
2037-01-07 Wed	89	—	unknown	19:35–01:55 (good, 6.33 h)	42.9° 22:45	11.37	59%	104.6°
2037-01-08 Thu	89	—	unknown	19:30–01:55 (good, 6.42 h)	42.9° 22:45	11.35	48%	117.0°
2037-01-09 Fri	89	—	unknown	19:25–02:00 (good, 6.58 h)	42.9° 22:40	11.34	37%	128.7°
2037-01-10 Sat	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.32	27%	139.4°
2037-01-11 Sun	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.3	19%	148.4°
2037-01-12 Mon	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:25	11.28	11%	154.1°
2037-01-13 Tue	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.26	6%	154.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-12-15&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.