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: 01-20 (89), 01-21 (89), 01-22 (89), 01-23 (89), 01-24 (89) — by astronomy; check the weather when the night is within four days.

2033-01-16astronomy score per night — click a bar for that night2033-02-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2033-01-16 Sun	38	—	unknown	18:55–01:10 (marginal, 6.25 h)	42.9° 22:10	11.2	98%	52.9°
2033-01-17 Mon	75	—	unknown	19:00–19:35 (good, 0.58 h)	42.9° 22:10	11.17	94%	63.5°
2033-01-18 Tue	86	—	unknown	19:00–23:05 (good, 4.08 h)	42.9° 22:05	11.15	89%	74.2°
2033-01-19 Wed	88	—	unknown	19:00–00:35 (good, 5.58 h)	42.9° 22:00	11.12	83%	85.0°
2033-01-20 Thu	89	—	unknown	19:00–00:55 (good, 5.92 h)	42.9° 21:55	11.1	75%	95.7°
2033-01-21 Fri	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:50	11.07	67%	106.5°
2033-01-22 Sat	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:50	11.05	58%	117.2°
2033-01-23 Sun	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.02	48%	127.7°
2033-01-24 Mon	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	10.99	38%	137.9°
2033-01-25 Tue	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:35	10.96	29%	147.2°
2033-01-26 Wed	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.93	20%	153.9°
2033-01-27 Thu	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.91	12%	155.3°
2033-01-28 Fri	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.87	6%	150.0°
2033-01-29 Sat	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.84	2%	140.1°
2033-01-30 Sun	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:15	10.81	0%	128.1°
2033-01-31 Mon	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:15	10.78	2%	115.0°
2033-02-01 Tue	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.75	6%	101.5°
2033-02-02 Wed	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.71	13%	87.9°
2033-02-03 Thu	87	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.68	22%	74.6°
2033-02-04 Fri	81	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.65	32%	61.7°
2033-02-05 Sat	64	—	unknown	19:20–23:55 (good, 4.58 h)	42.9° 20:55	10.61	43%	49.6°
2033-02-06 Sun	46	—	unknown	19:20–00:40 (marginal, 5.33 h)	42.9° 20:50	10.58	54%	38.6°
2033-02-07 Mon	30	—	unknown	19:20–00:25 (marginal, 5.08 h)	42.9° 20:45	10.54	65%	29.7°
2033-02-08 Tue	21	—	unknown	19:20–00:05 (marginal, 4.75 h)	42.9° 20:40	10.5	74%	24.7°
2033-02-09 Wed	14	—	unknown	19:25–23:35 (marginal, 4.17 h)	42.9° 20:35	10.47	82%	25.5°
2033-02-10 Thu	12	—	unknown	19:25–20:40 (marginal, 1.25 h)	42.9° 20:35	10.43	89%	31.5°
2033-02-11 Fri	15	—	unknown	19:25–22:00 (marginal, 2.58 h)	42.9° 20:30	10.39	95%	40.1°
2033-02-12 Sat	20	—	unknown	19:25–23:20 (marginal, 3.92 h)	42.9° 20:25	10.35	98%	50.1°
2033-02-13 Sun	28	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:20	10.31	100%	60.5°
2033-02-14 Mon	38	—	unknown	19:30–19:55 (good, 0.42 h)	42.9° 20:20	10.27	100%	71.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2033-01-16&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.