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: 10-27 (86), 10-12 (82), 10-13 (82), 10-14 (81), 10-26 (81) — by astronomy; check the weather when the night is within four days.

2043-09-28astronomy score per night — click a bar for that night2043-10-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-09-28 Mon	51	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:25	9.03	18%	60.0°
2043-09-29 Tue	56	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.08	10%	70.5°
2043-09-30 Wed	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.13	5%	81.1°
2043-10-01 Thu	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.17	2%	91.7°
2043-10-02 Fri	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.22	0%	102.1°
2043-10-03 Sat	67	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.27	1%	112.2°
2043-10-04 Sun	68	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.32	3%	121.7°
2043-10-05 Mon	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.36	7%	130.4°
2043-10-06 Tue	72	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.41	13%	137.8°
2043-10-07 Wed	74	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:50	9.46	20%	143.3°
2043-10-08 Thu	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.5	28%	146.0°
2043-10-09 Fri	76	—	unknown	02:30–05:55 (good, 3.42 h)	42.9° 05:45	9.55	37%	145.2°
2043-10-10 Sat	78	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.59	46%	141.0°
2043-10-11 Sun	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.64	56%	134.2°
2043-10-12 Mon	82	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:30	9.68	66%	125.7°
2043-10-13 Tue	82	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:30	9.73	75%	116.0°
2043-10-14 Wed	81	—	unknown	02:25–06:05 (good, 3.67 h)	42.9° 05:25	9.77	84%	105.3°
2043-10-15 Thu	75	—	unknown	02:35–06:05 (good, 3.5 h)	42.9° 05:20	9.82	91%	94.0°
2043-10-16 Fri	65	—	unknown	03:40–06:05 (good, 2.42 h)	42.9° 05:15	9.86	96%	82.2°
2043-10-17 Sat	37	—	unknown	06:00–06:05 (good, 0.08 h)	42.9° 05:15	9.9	100%	70.3°
2043-10-18 Sun	25	—	unknown	02:05–06:05 (marginal, 4.0 h)	42.9° 05:10	9.94	100%	58.7°
2043-10-19 Mon	17	—	unknown	02:35–06:10 (marginal, 3.58 h)	42.9° 05:05	9.99	97%	47.9°
2043-10-20 Tue	13	—	unknown	03:55–06:10 (marginal, 2.25 h)	42.9° 05:00	10.03	91%	39.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-09-28&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.