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: 10-05 (70), 10-04 (69), 10-06 (68), 10-03 (67), 10-02 (66) — by astronomy; check the weather when the night is within four days.

2041-09-14astronomy score per night — click a bar for that night2041-10-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-09-14 Sat	8	—	unknown	04:05–05:30 (marginal, 1.42 h)	42.9° 07:20	8.34	74%	40.8°
2041-09-15 Sun	10	—	unknown	03:55–05:30 (marginal, 1.58 h)	42.9° 07:15	8.39	63%	34.5°
2041-09-16 Mon	14	—	unknown	03:35–05:30 (marginal, 1.92 h)	42.9° 07:10	8.44	53%	32.3°
2041-09-17 Tue	20	—	unknown	03:25–05:35 (marginal, 2.17 h)	42.9° 07:10	8.5	43%	34.5°
2041-09-18 Wed	26	—	unknown	04:15–05:35 (good, 1.33 h)	42.9° 07:05	8.55	33%	40.1°
2041-09-19 Thu	33	—	unknown	04:00–05:35 (good, 1.58 h)	42.9° 07:00	8.6	25%	47.7°
2041-09-20 Fri	39	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 06:55	8.65	17%	56.5°
2041-09-21 Sat	44	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:55	8.7	10%	65.8°
2041-09-22 Sun	47	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.75	5%	75.6°
2041-09-23 Mon	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.8	2%	85.5°
2041-09-24 Tue	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.85	0%	95.5°
2041-09-25 Wed	53	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:35	8.9	0%	105.5°
2041-09-26 Thu	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.95	2%	115.4°
2041-09-27 Fri	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.0	6%	124.9°
2041-09-28 Sat	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.05	12%	133.7°
2041-09-29 Sun	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.1	19%	141.3°
2041-09-30 Mon	63	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:15	9.15	27%	146.3°
2041-10-01 Tue	64	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.2	37%	147.4°
2041-10-02 Wed	66	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.24	48%	144.0°
2041-10-03 Thu	67	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.29	59%	136.8°
2041-10-04 Fri	69	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:00	9.34	70%	127.2°
2041-10-05 Sat	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.39	80%	116.0°
2041-10-06 Sun	68	—	unknown	02:55–05:55 (good, 3.0 h)	42.9° 05:55	9.43	88%	103.9°
2041-10-07 Mon	62	—	unknown	03:05–05:55 (good, 2.83 h)	42.9° 05:50	9.48	95%	91.4°
2041-10-08 Tue	39	—	unknown	04:35–05:55 (good, 1.33 h)	42.9° 05:45	9.53	99%	78.7°
2041-10-09 Wed	28	—	unknown	02:25–06:00 (marginal, 3.58 h)	42.9° 05:40	9.57	100%	66.3°
2041-10-10 Thu	19	—	unknown	02:40–06:00 (marginal, 3.33 h)	42.9° 05:40	9.62	98%	54.7°
2041-10-11 Fri	14	—	unknown	02:55–06:00 (marginal, 3.08 h)	42.9° 05:35	9.66	94%	44.4°
2041-10-12 Sat	12	—	unknown	02:50–06:00 (marginal, 3.17 h)	42.9° 05:30	9.71	87%	36.7°
2041-10-13 Sun	14	—	unknown	02:25–06:00 (marginal, 3.58 h)	42.9° 05:25	9.75	78%	32.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-14&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.