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.

2041-10-13astronomy score per night — click a bar for that night2041-11-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-10-13 Sun	14	—	unknown	02:25–06:00 (marginal, 3.58 h)	42.9° 05:25	9.75	78%	32.7°
2041-10-14 Mon	20	—	unknown	02:00–06:05 (marginal, 4.08 h)	42.9° 05:20	9.79	69%	33.4°
2041-10-15 Tue	31	—	unknown	01:40–06:05 (marginal, 4.42 h)	42.9° 05:20	9.84	60%	38.2°
2041-10-16 Wed	44	—	unknown	02:35–05:45 (good, 3.17 h)	42.9° 05:15	9.88	50%	45.4°
2041-10-17 Thu	57	—	unknown	02:15–06:05 (good, 3.83 h)	42.9° 05:10	9.92	40%	53.9°
2041-10-18 Fri	71	—	unknown	02:00–06:10 (good, 4.17 h)	42.9° 05:05	9.97	31%	63.2°
2041-10-19 Sat	82	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	10.01	22%	72.8°
2041-10-20 Sun	87	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.05	15%	82.7°
2041-10-21 Mon	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.09	9%	92.7°
2041-10-22 Tue	89	—	unknown	01:35–06:10 (good, 4.58 h)	42.9° 04:50	10.13	4%	102.7°
2041-10-23 Wed	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:45	10.17	1%	112.7°
2041-10-24 Thu	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.21	0%	122.4°
2041-10-25 Fri	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.25	1%	131.6°
2041-10-26 Sat	89	—	unknown	01:20–05:15 (good, 4.92 h)	42.9° 03:35	10.29	3%	139.6°
2041-10-27 Sun	89	—	unknown	00:15–05:15 (good, 5.0 h)	42.9° 03:30	10.33	8%	145.4°
2041-10-28 Mon	89	—	unknown	00:15–05:20 (good, 5.08 h)	42.9° 03:25	10.37	15%	147.5°
2041-10-29 Tue	89	—	unknown	00:10–05:20 (good, 5.17 h)	42.9° 03:25	10.4	23%	145.2°
2041-10-30 Wed	89	—	unknown	00:05–05:20 (good, 5.25 h)	42.9° 03:20	10.44	33%	138.8°
2041-10-31 Thu	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.48	44%	129.9°
2041-11-01 Fri	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.51	55%	119.4°
2041-11-02 Sat	89	—	unknown	00:05–05:25 (good, 5.33 h)	42.9° 03:10	10.55	66%	107.9°
2041-11-03 Sun	89	—	unknown	00:10–05:25 (good, 5.25 h)	42.9° 03:05	10.59	76%	95.9°
2041-11-04 Mon	89	—	unknown	00:35–05:25 (good, 4.83 h)	42.9° 03:00	10.62	86%	83.6°
2041-11-05 Tue	83	—	unknown	02:30–05:25 (good, 2.92 h)	42.9° 02:55	10.66	93%	71.4°
2041-11-06 Wed	44	—	unknown	23:45–05:30 (marginal, 5.75 h)	42.9° 02:50	10.69	98%	59.6°
2041-11-07 Thu	28	—	unknown	00:20–05:30 (marginal, 5.17 h)	42.9° 02:50	10.72	100%	48.8°
2041-11-08 Fri	18	—	unknown	03:05–05:30 (marginal, 2.42 h)	42.9° 02:45	10.76	99%	39.7°
2041-11-09 Sat	13	—	unknown	05:20–05:25 (marginal, 0.08 h)	42.9° 02:40	10.79	96%	33.9°
2041-11-10 Sun	13	—	unknown	—	42.9° 02:35	10.82	91%	32.6°
2041-11-11 Mon	22	—	unknown	23:20–05:25 (marginal, 6.08 h)	42.9° 02:30	10.85	84%	35.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-10-13&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.