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: 10-18 (89), 10-19 (89), 10-20 (89), 10-21 (89), 10-22 (89) — by astronomy; check the weather when the night is within four days.

2042-10-18astronomy score per night — click a bar for that night2042-11-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-10-18 Sat	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.95	20%	146.4°
2042-10-19 Sun	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	10.0	28%	145.5°
2042-10-20 Mon	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.04	38%	140.8°
2042-10-21 Tue	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.08	48%	133.4°
2042-10-22 Wed	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:50	10.12	58%	124.1°
2042-10-23 Thu	89	—	unknown	01:40–06:15 (good, 4.58 h)	42.9° 04:50	10.16	69%	113.5°
2042-10-24 Fri	89	—	unknown	01:45–06:15 (good, 4.5 h)	42.9° 04:45	10.2	79%	102.1°
2042-10-25 Sat	89	—	unknown	01:55–05:15 (good, 4.33 h)	42.9° 03:40	10.24	88%	90.0°
2042-10-26 Sun	76	—	unknown	02:25–05:15 (good, 2.83 h)	42.9° 03:35	10.28	94%	77.6°
2042-10-27 Mon	41	—	unknown	00:15–05:15 (marginal, 5.0 h)	42.9° 03:30	10.32	99%	65.2°
2042-10-28 Tue	27	—	unknown	00:40–05:20 (marginal, 4.67 h)	42.9° 03:30	10.36	100%	53.5°
2042-10-29 Wed	17	—	unknown	02:30–05:20 (marginal, 2.83 h)	42.9° 03:25	10.4	98%	43.3°
2042-10-30 Thu	13	—	unknown	04:20–05:20 (marginal, 1.0 h)	42.9° 03:20	10.43	93%	36.1°
2042-10-31 Fri	14	—	unknown	00:30–05:20 (marginal, 4.83 h)	42.9° 03:15	10.47	86%	33.4°
2042-11-01 Sat	23	—	unknown	23:55–05:25 (marginal, 5.5 h)	42.9° 03:15	10.51	78%	36.0°
2042-11-02 Sun	37	—	unknown	23:30–05:25 (marginal, 5.92 h)	42.9° 03:10	10.54	68%	42.5°
2042-11-03 Mon	55	—	unknown	00:30–02:50 (good, 2.33 h)	42.9° 03:05	10.58	58%	51.1°
2042-11-04 Tue	70	—	unknown	00:05–05:25 (good, 5.33 h)	42.9° 03:00	10.61	47%	60.6°
2042-11-05 Wed	81	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 02:55	10.65	38%	70.4°
2042-11-06 Thu	86	—	unknown	23:40–05:30 (good, 5.83 h)	42.9° 02:55	10.68	28%	80.5°
2042-11-07 Fri	89	—	unknown	23:35–05:30 (good, 5.92 h)	42.9° 02:50	10.71	20%	90.5°
2042-11-08 Sat	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:45	10.75	13%	100.4°
2042-11-09 Sun	89	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.78	8%	110.1°
2042-11-10 Mon	89	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:35	10.81	3%	119.5°
2042-11-11 Tue	89	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.84	1%	128.3°
2042-11-12 Wed	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.87	0%	136.2°
2042-11-13 Thu	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.9	1%	142.5°
2042-11-14 Fri	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.93	4%	146.2°
2042-11-15 Sat	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.96	9%	146.1°
2042-11-16 Sun	89	—	unknown	23:00–05:35 (good, 6.58 h)	42.9° 02:15	10.99	15%	142.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-10-18&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.