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: 10-16 (87), 10-15 (83), 10-14 (73), 10-13 (59), 09-28 (58) — by astronomy; check the weather when the night is within four days.

2047-09-17astronomy score per night — click a bar for that night2047-10-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-09-17 Tue	38	—	unknown	03:55–05:30 (good, 1.58 h)	42.9° 07:10	8.47	5%	68.3°
2047-09-18 Wed	41	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.52	1%	80.4°
2047-09-19 Thu	42	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.58	0%	92.9°
2047-09-20 Fri	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.63	2%	105.6°
2047-09-21 Sat	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.68	7%	118.1°
2047-09-22 Sun	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.73	14%	129.8°
2047-09-23 Mon	50	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:45	8.78	23%	140.0°
2047-09-24 Tue	51	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.83	34%	147.3°
2047-09-25 Wed	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.88	45%	149.8°
2047-09-26 Thu	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.93	56%	146.7°
2047-09-27 Fri	56	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	8.98	66%	139.6°
2047-09-28 Sat	58	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:25	9.03	76%	130.4°
2047-09-29 Sun	58	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:25	9.08	84%	120.2°
2047-09-30 Mon	58	—	unknown	03:20–05:50 (good, 2.5 h)	42.9° 06:20	9.13	91%	109.6°
2047-10-01 Tue	53	—	unknown	03:25–05:50 (good, 2.42 h)	42.9° 06:15	9.18	96%	98.9°
2047-10-02 Wed	37	—	unknown	04:05–05:50 (good, 1.75 h)	42.9° 06:10	9.22	99%	88.2°
2047-10-03 Thu	29	—	unknown	05:35–05:50 (good, 0.25 h)	42.9° 06:10	9.27	100%	77.7°
2047-10-04 Fri	22	—	unknown	02:45–05:50 (marginal, 3.08 h)	42.9° 06:05	9.32	99%	67.5°
2047-10-05 Sat	17	—	unknown	02:55–05:55 (marginal, 3.0 h)	42.9° 06:00	9.37	96%	57.6°
2047-10-06 Sun	14	—	unknown	03:05–05:55 (marginal, 2.83 h)	42.9° 05:55	9.41	92%	48.4°
2047-10-07 Mon	12	—	unknown	03:05–05:55 (marginal, 2.83 h)	42.9° 05:50	9.46	86%	40.3°
2047-10-08 Tue	12	—	unknown	02:50–05:55 (marginal, 3.08 h)	42.9° 05:50	9.5	79%	33.8°
2047-10-09 Wed	16	—	unknown	02:30–06:00 (marginal, 3.5 h)	42.9° 05:45	9.55	71%	30.4°
2047-10-10 Thu	23	—	unknown	02:10–06:00 (marginal, 3.83 h)	42.9° 05:40	9.6	62%	30.9°
2047-10-11 Fri	33	—	unknown	01:55–06:00 (marginal, 4.08 h)	42.9° 05:35	9.64	53%	35.5°
2047-10-12 Sat	46	—	unknown	02:45–06:00 (good, 3.25 h)	42.9° 05:30	9.69	43%	43.1°
2047-10-13 Sun	59	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:30	9.73	33%	52.5°
2047-10-14 Mon	73	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:25	9.77	23%	63.3°
2047-10-15 Tue	83	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.82	14%	74.9°
2047-10-16 Wed	87	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.86	7%	87.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-09-17&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.