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: 10-15 (87), 10-16 (87), 10-14 (86), 10-17 (86), 10-13 (83) — by astronomy; check the weather when the night is within four days.

2029-09-20astronomy score per night — click a bar for that night2029-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-09-20 Thu	33	—	unknown	04:05–05:35 (good, 1.5 h)	42.9° 06:55	8.65	97%	105.0°
2029-09-21 Fri	29	—	unknown	04:10–05:40 (good, 1.5 h)	42.9° 06:55	8.7	99%	94.4°
2029-09-22 Sat	23	—	unknown	05:20–05:40 (good, 0.33 h)	42.9° 06:50	8.75	100%	83.8°
2029-09-23 Sun	19	—	unknown	03:20–05:40 (marginal, 2.33 h)	42.9° 06:45	8.8	98%	73.4°
2029-09-24 Mon	15	—	unknown	03:25–05:40 (marginal, 2.25 h)	42.9° 06:40	8.85	95%	63.3°
2029-09-25 Tue	12	—	unknown	03:35–05:40 (marginal, 2.08 h)	42.9° 06:35	8.9	91%	53.6°
2029-09-26 Wed	11	—	unknown	03:35–05:45 (marginal, 2.17 h)	42.9° 06:35	8.95	84%	44.6°
2029-09-27 Thu	11	—	unknown	03:25–05:45 (marginal, 2.33 h)	42.9° 06:30	9.0	77%	36.8°
2029-09-28 Fri	13	—	unknown	03:10–05:45 (marginal, 2.58 h)	42.9° 06:25	9.05	69%	31.1°
2029-09-29 Sat	19	—	unknown	02:50–05:45 (marginal, 2.92 h)	42.9° 06:20	9.1	59%	29.1°
2029-09-30 Sun	27	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:15	9.14	50%	31.6°
2029-10-01 Mon	36	—	unknown	03:25–05:50 (good, 2.42 h)	42.9° 06:15	9.19	39%	38.0°
2029-10-02 Tue	47	—	unknown	03:10–05:50 (good, 2.67 h)	42.9° 06:10	9.24	29%	47.0°
2029-10-03 Wed	57	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.29	20%	57.7°
2029-10-04 Thu	65	—	unknown	02:45–05:50 (good, 3.08 h)	42.9° 06:00	9.34	12%	69.5°
2029-10-05 Fri	71	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.38	5%	82.0°
2029-10-06 Sat	72	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.43	1%	95.0°
2029-10-07 Sun	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.48	0%	108.1°
2029-10-08 Mon	75	—	unknown	02:30–05:55 (good, 3.42 h)	42.9° 05:45	9.52	2%	120.9°
2029-10-09 Tue	78	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:40	9.57	7%	132.9°
2029-10-10 Wed	79	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.61	14%	143.0°
2029-10-11 Thu	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.66	23%	149.6°
2029-10-12 Fri	82	—	unknown	02:15–06:00 (good, 3.75 h)	42.9° 05:30	9.7	33%	150.6°
2029-10-13 Sat	83	—	unknown	02:10–06:00 (good, 3.83 h)	42.9° 05:25	9.75	44%	146.1°
2029-10-14 Sun	86	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:20	9.79	55%	138.1°
2029-10-15 Mon	87	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.83	65%	128.5°
2029-10-16 Tue	87	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:15	9.88	74%	118.2°
2029-10-17 Wed	86	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:10	9.92	82%	107.7°
2029-10-18 Thu	82	—	unknown	02:20–06:10 (good, 3.83 h)	42.9° 05:05	9.96	89%	97.1°
2029-10-19 Fri	74	—	unknown	03:00–06:10 (good, 3.17 h)	42.9° 05:00	10.0	94%	86.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-09-20&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.