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: 12-31 (89), 01-01 (89), 01-02 (89), 01-03 (89), 01-04 (89) — by astronomy; check the weather when the night is within four days.

2034-12-21astronomy score per night — click a bar for that night2035-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-12-21 Thu	43	—	unknown	20:45–03:45 (marginal, 7.0 h)	42.9° 23:55	11.51	83%	46.3°
2034-12-22 Fri	24	—	unknown	22:40–03:20 (marginal, 4.67 h)	42.9° 23:50	11.51	91%	34.7°
2034-12-23 Sat	14	—	unknown	—	42.9° 23:50	11.51	97%	26.0°
2034-12-24 Sun	10	—	unknown	—	42.9° 23:45	11.5	100%	24.0°
2034-12-25 Mon	13	—	unknown	—	42.9° 23:40	11.5	99%	30.1°
2034-12-26 Tue	25	—	unknown	20:10–00:50 (marginal, 4.67 h)	42.9° 23:35	11.5	96%	40.7°
2034-12-27 Wed	43	—	unknown	19:45–02:40 (marginal, 6.92 h)	42.9° 23:30	11.49	91%	52.7°
2034-12-28 Thu	81	—	unknown	20:15–23:15 (good, 3.0 h)	42.9° 23:30	11.48	83%	65.2°
2034-12-29 Fri	86	—	unknown	20:10–01:35 (good, 5.42 h)	42.9° 23:25	11.48	74%	77.5°
2034-12-30 Sat	88	—	unknown	20:05–02:15 (good, 6.17 h)	42.9° 23:20	11.47	65%	89.5°
2034-12-31 Sun	89	—	unknown	20:00–02:25 (good, 6.42 h)	42.9° 23:15	11.46	55%	101.1°
2035-01-01 Mon	89	—	unknown	20:00–02:25 (good, 6.42 h)	42.9° 23:15	11.45	45%	112.3°
2035-01-02 Tue	89	—	unknown	19:55–02:25 (good, 6.5 h)	42.9° 23:10	11.44	36%	123.1°
2035-01-03 Wed	89	—	unknown	19:50–02:25 (good, 6.58 h)	42.9° 23:05	11.43	27%	133.3°
2035-01-04 Thu	89	—	unknown	19:45–02:20 (good, 6.58 h)	42.9° 23:00	11.42	19%	142.8°
2035-01-05 Fri	89	—	unknown	19:45–02:15 (good, 6.5 h)	42.9° 22:55	11.4	12%	150.7°
2035-01-06 Sat	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:55	11.39	7%	155.7°
2035-01-07 Sun	89	—	unknown	19:35–02:10 (good, 6.58 h)	42.9° 22:50	11.38	3%	155.7°
2035-01-08 Mon	89	—	unknown	19:30–02:05 (good, 6.58 h)	42.9° 22:45	11.36	1%	150.6°
2035-01-09 Tue	89	—	unknown	19:25–02:00 (good, 6.58 h)	42.9° 22:40	11.34	0%	142.4°
2035-01-10 Wed	89	—	unknown	19:25–01:55 (good, 6.5 h)	42.9° 22:35	11.33	2%	132.5°
2035-01-11 Thu	89	—	unknown	19:20–01:50 (good, 6.5 h)	42.9° 22:35	11.31	5%	121.7°
2035-01-12 Fri	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.29	11%	110.3°
2035-01-13 Sat	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:25	11.27	18%	98.6°
2035-01-14 Sun	89	—	unknown	19:15–01:40 (good, 6.42 h)	42.9° 22:20	11.25	26%	86.6°
2035-01-15 Mon	87	—	unknown	19:20–01:35 (good, 6.25 h)	42.9° 22:20	11.23	36%	74.4°
2035-01-16 Tue	83	—	unknown	19:30–01:35 (good, 6.08 h)	42.9° 22:15	11.21	47%	62.1°
2035-01-17 Wed	64	—	unknown	21:35–01:00 (good, 3.42 h)	42.9° 22:10	11.18	58%	49.9°
2035-01-18 Thu	44	—	unknown	19:00–01:50 (marginal, 6.83 h)	42.9° 22:05	11.16	69%	38.3°
2035-01-19 Fri	26	—	unknown	19:10–01:30 (marginal, 6.33 h)	42.9° 22:00	11.14	80%	28.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-12-21&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.