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: 10-28 (89), 10-29 (89), 10-30 (89), 10-31 (89), 11-01 (89) — by astronomy; check the weather when the night is within four days.

2043-10-21astronomy score per night — click a bar for that night2043-11-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-10-21 Wed	14	—	unknown	02:05–06:10 (marginal, 4.08 h)	42.9° 04:55	10.07	84%	34.4°
2043-10-22 Thu	21	—	unknown	01:35–06:10 (marginal, 4.58 h)	42.9° 04:55	10.11	74%	34.7°
2043-10-23 Fri	34	—	unknown	01:10–06:15 (marginal, 5.08 h)	42.9° 04:50	10.15	63%	39.9°
2043-10-24 Sat	50	—	unknown	02:05–04:15 (good, 3.17 h)	42.9° 03:45	10.19	52%	48.0°
2043-10-25 Sun	67	—	unknown	00:45–05:15 (good, 4.5 h)	42.9° 03:40	10.23	41%	57.7°
2043-10-26 Mon	81	—	unknown	00:25–05:15 (good, 4.83 h)	42.9° 03:35	10.27	31%	68.0°
2043-10-27 Tue	86	—	unknown	00:20–05:15 (good, 4.92 h)	42.9° 03:35	10.31	22%	78.5°
2043-10-28 Wed	89	—	unknown	00:15–05:20 (good, 5.08 h)	42.9° 03:30	10.35	14%	89.0°
2043-10-29 Thu	89	—	unknown	00:10–05:20 (good, 5.17 h)	42.9° 03:25	10.39	8%	99.4°
2043-10-30 Fri	89	—	unknown	00:05–05:20 (good, 5.25 h)	42.9° 03:20	10.42	3%	109.4°
2043-10-31 Sat	89	—	unknown	00:05–05:20 (good, 5.25 h)	42.9° 03:20	10.46	1%	119.1°
2043-11-01 Sun	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.5	0%	128.0°
2043-11-02 Mon	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.53	1%	135.9°
2043-11-03 Tue	89	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:05	10.57	4%	142.1°
2043-11-04 Wed	89	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:00	10.6	8%	145.7°
2043-11-05 Thu	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 03:00	10.64	14%	145.9°
2043-11-06 Fri	89	—	unknown	23:40–05:30 (good, 5.83 h)	42.9° 02:55	10.67	22%	142.6°
2043-11-07 Sat	89	—	unknown	23:35–05:30 (good, 5.92 h)	42.9° 02:50	10.71	30%	136.6°
2043-11-08 Sun	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:45	10.74	39%	128.8°
2043-11-09 Mon	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:40	10.77	49%	119.6°
2043-11-10 Tue	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:40	10.8	59%	109.5°
2043-11-11 Wed	89	—	unknown	23:35–05:35 (good, 6.0 h)	42.9° 02:35	10.84	69%	98.8°
2043-11-12 Thu	89	—	unknown	23:45–05:35 (good, 5.83 h)	42.9° 02:30	10.87	79%	87.4°
2043-11-13 Fri	86	—	unknown	01:10–05:35 (good, 4.42 h)	42.9° 02:25	10.9	87%	75.8°
2043-11-14 Sat	74	—	unknown	05:05–05:35 (good, 0.5 h)	42.9° 02:20	10.93	94%	64.0°
2043-11-15 Sun	34	—	unknown	23:30–05:35 (marginal, 6.08 h)	42.9° 02:20	10.96	98%	52.7°
2043-11-16 Mon	21	—	unknown	02:00–05:35 (marginal, 3.58 h)	42.9° 02:15	10.98	100%	42.8°
2043-11-17 Tue	13	—	unknown	—	42.9° 02:10	11.01	98%	35.8°
2043-11-18 Wed	13	—	unknown	—	42.9° 02:05	11.04	94%	33.8°
2043-11-19 Thu	22	—	unknown	22:50–04:50 (marginal, 6.0 h)	42.9° 02:05	11.07	87%	37.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-10-21&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.