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: 01-22 (89), 01-23 (89), 01-24 (89), 01-25 (89), 01-26 (89) — by astronomy; check the weather when the night is within four days.

2041-01-19astronomy score per night — click a bar for that night2041-02-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-01-19 Sat	79	—	unknown	19:00–21:25 (good, 2.42 h)	42.9° 22:00	11.12	94%	71.6°
2041-01-20 Sun	86	—	unknown	19:00–23:35 (good, 4.58 h)	42.9° 21:55	11.1	88%	81.7°
2041-01-21 Mon	88	—	unknown	19:05–00:40 (good, 5.58 h)	42.9° 21:50	11.07	82%	91.9°
2041-01-22 Tue	89	—	unknown	19:05–00:50 (good, 5.75 h)	42.9° 21:50	11.05	74%	102.1°
2041-01-23 Wed	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:45	11.02	65%	112.4°
2041-01-24 Thu	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:40	10.99	55%	122.5°
2041-01-25 Fri	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:35	10.96	45%	132.2°
2041-01-26 Sat	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.93	34%	140.8°
2041-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.9	24%	147.0°
2041-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.87	15%	148.6°
2041-01-29 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.84	8%	144.6°
2041-01-30 Wed	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:15	10.81	3%	136.2°
2041-01-31 Thu	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:15	10.78	0%	125.1°
2041-02-01 Fri	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.75	1%	112.8°
2041-02-02 Sat	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.71	5%	100.1°
2041-02-03 Sun	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.68	11%	87.3°
2041-02-04 Mon	88	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.64	19%	75.0°
2041-02-05 Tue	84	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:55	10.61	29%	63.3°
2041-02-06 Wed	69	—	unknown	19:20–23:55 (good, 4.58 h)	42.9° 20:50	10.57	39%	52.6°
2041-02-07 Thu	52	—	unknown	20:00–23:35 (good, 3.58 h)	42.9° 20:45	10.54	50%	43.3°
2041-02-08 Fri	36	—	unknown	19:20–00:25 (marginal, 5.08 h)	42.9° 20:40	10.5	60%	36.0°
2041-02-09 Sat	24	—	unknown	19:25–00:10 (marginal, 4.75 h)	42.9° 20:35	10.46	69%	31.9°
2041-02-10 Sun	16	—	unknown	19:25–23:45 (marginal, 4.33 h)	42.9° 20:35	10.43	78%	31.8°
2041-02-11 Mon	14	—	unknown	19:25–23:20 (marginal, 3.92 h)	42.9° 20:30	10.39	85%	35.6°
2041-02-12 Tue	14	—	unknown	19:25–22:40 (marginal, 3.25 h)	42.9° 20:25	10.35	91%	42.2°
2041-02-13 Wed	18	—	unknown	19:30–23:10 (marginal, 3.67 h)	42.9° 20:20	10.31	96%	50.4°
2041-02-14 Thu	24	—	unknown	19:30–23:25 (marginal, 3.92 h)	42.9° 20:20	10.27	99%	59.5°
2041-02-15 Fri	32	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:15	10.23	100%	69.1°
2041-02-16 Sat	41	—	unknown	19:30–20:45 (good, 1.25 h)	42.9° 20:10	10.19	99%	79.1°
2041-02-17 Sun	52	—	unknown	19:35–22:15 (good, 2.67 h)	42.9° 20:05	10.15	97%	89.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-19&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.