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: 10-21 (89), 10-22 (89), 10-23 (89), 10-24 (89), 10-25 (89) — by astronomy; check the weather when the night is within four days.

2039-10-21astronomy score per night — click a bar for that night2039-11-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-10-21 Fri	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 04:55	10.07	22%	150.4°
2039-10-22 Sat	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.11	32%	145.6°
2039-10-23 Sun	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:50	10.15	44%	137.0°
2039-10-24 Mon	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.19	55%	126.6°
2039-10-25 Tue	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:40	10.23	66%	115.4°
2039-10-26 Wed	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:35	10.27	75%	104.0°
2039-10-27 Thu	89	—	unknown	01:45–06:15 (good, 4.5 h)	42.9° 04:35	10.31	84%	92.5°
2039-10-28 Fri	88	—	unknown	02:25–06:20 (good, 3.92 h)	42.9° 04:30	10.35	91%	81.2°
2039-10-29 Sat	73	—	unknown	03:15–05:20 (good, 2.08 h)	42.9° 03:25	10.38	96%	70.2°
2039-10-30 Sun	39	—	unknown	00:10–05:20 (marginal, 5.17 h)	42.9° 03:20	10.42	99%	59.7°
2039-10-31 Mon	27	—	unknown	00:30–05:20 (marginal, 4.83 h)	42.9° 03:15	10.46	100%	49.8°
2039-11-01 Tue	18	—	unknown	02:30–05:20 (marginal, 2.83 h)	42.9° 03:15	10.5	99%	41.0°
2039-11-02 Wed	13	—	unknown	04:25–05:25 (marginal, 1.0 h)	42.9° 03:10	10.53	96%	34.0°
2039-11-03 Thu	12	—	unknown	—	42.9° 03:05	10.57	92%	30.0°
2039-11-04 Fri	15	—	unknown	00:15–01:25 (marginal, 1.17 h)	42.9° 03:00	10.6	86%	30.0°
2039-11-05 Sat	23	—	unknown	23:40–05:25 (marginal, 5.75 h)	42.9° 03:00	10.64	79%	34.0°
2039-11-06 Sun	36	—	unknown	23:20–05:30 (marginal, 6.17 h)	42.9° 02:55	10.67	71%	40.8°
2039-11-07 Mon	52	—	unknown	23:05–05:30 (marginal, 6.42 h)	42.9° 02:50	10.71	62%	49.3°
2039-11-08 Tue	67	—	unknown	23:55–04:40 (good, 4.75 h)	42.9° 02:45	10.74	52%	58.9°
2039-11-09 Wed	81	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:40	10.77	42%	69.3°
2039-11-10 Thu	86	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.8	33%	80.2°
2039-11-11 Fri	88	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.83	23%	91.6°
2039-11-12 Sat	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.87	15%	103.4°
2039-11-13 Sun	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.9	8%	115.4°
2039-11-14 Mon	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:20	10.93	3%	127.2°
2039-11-15 Tue	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.95	0%	138.1°
2039-11-16 Wed	89	—	unknown	23:00–05:35 (good, 6.58 h)	42.9° 02:15	10.98	1%	146.8°
2039-11-17 Thu	89	—	unknown	22:55–05:30 (good, 6.58 h)	42.9° 02:10	11.01	4%	150.6°
2039-11-18 Fri	89	—	unknown	22:55–05:25 (good, 6.5 h)	42.9° 02:05	11.04	10%	147.7°
2039-11-19 Sat	89	—	unknown	22:50–05:20 (good, 6.5 h)	42.9° 02:05	11.06	19%	139.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-10-21&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.