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: 11-03 (89), 11-04 (89), 11-05 (89), 11-06 (89), 11-07 (89) — by astronomy; check the weather when the night is within four days.

2037-10-20astronomy score per night — click a bar for that night2037-11-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-10-20 Tue	82	—	unknown	02:15–06:10 (good, 3.92 h)	42.9° 05:00	10.05	90%	88.8°
2037-10-21 Wed	72	—	unknown	03:30–06:10 (good, 2.67 h)	42.9° 04:55	10.09	95%	78.2°
2037-10-22 Thu	43	—	unknown	05:25–06:10 (good, 0.75 h)	42.9° 04:50	10.13	98%	67.6°
2037-10-23 Fri	32	—	unknown	01:40–06:15 (marginal, 4.58 h)	42.9° 04:45	10.17	100%	57.3°
2037-10-24 Sat	22	—	unknown	02:00–05:15 (marginal, 4.25 h)	42.9° 03:45	10.21	99%	47.2°
2037-10-25 Sun	15	—	unknown	03:05–05:15 (marginal, 2.17 h)	42.9° 03:40	10.25	97%	38.0°
2037-10-26 Mon	12	—	unknown	04:50–05:15 (marginal, 0.42 h)	42.9° 03:35	10.29	93%	30.5°
2037-10-27 Tue	13	—	unknown	04:25–05:15 (marginal, 0.83 h)	42.9° 03:30	10.33	87%	26.4°
2037-10-28 Wed	18	—	unknown	00:20–05:20 (marginal, 5.0 h)	42.9° 03:25	10.37	79%	27.5°
2037-10-29 Thu	29	—	unknown	23:55–05:20 (marginal, 5.42 h)	42.9° 03:25	10.4	70%	33.6°
2037-10-30 Fri	45	—	unknown	23:35–05:20 (marginal, 5.75 h)	42.9° 03:20	10.44	60%	42.7°
2037-10-31 Sat	64	—	unknown	00:25–05:05 (good, 4.67 h)	42.9° 03:15	10.48	50%	53.6°
2037-11-01 Sun	78	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.51	38%	65.5°
2037-11-02 Mon	86	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.55	28%	78.1°
2037-11-03 Tue	89	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:05	10.58	18%	91.1°
2037-11-04 Wed	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 03:00	10.62	10%	104.4°
2037-11-05 Thu	89	—	unknown	23:40–05:25 (good, 5.75 h)	42.9° 02:55	10.65	4%	117.5°
2037-11-06 Fri	89	—	unknown	23:40–05:30 (good, 5.83 h)	42.9° 02:50	10.69	1%	130.2°
2037-11-07 Sat	89	—	unknown	23:35–05:30 (good, 5.92 h)	42.9° 02:50	10.72	0%	141.6°
2037-11-08 Sun	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:45	10.75	3%	150.3°
2037-11-09 Mon	89	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.79	8%	153.9°
2037-11-10 Tue	89	—	unknown	23:20–05:30 (good, 6.17 h)	42.9° 02:35	10.82	15%	150.9°
2037-11-11 Wed	89	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:30	10.85	23%	143.4°
2037-11-12 Thu	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.88	32%	133.9°
2037-11-13 Fri	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.91	42%	123.6°
2037-11-14 Sat	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:20	10.94	52%	113.0°
2037-11-15 Sun	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:15	10.97	61%	102.4°
2037-11-16 Mon	89	—	unknown	23:20–05:30 (good, 6.17 h)	42.9° 02:15	11.0	70%	91.8°
2037-11-17 Tue	88	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:10	11.02	78%	81.2°
2037-11-18 Wed	86	—	unknown	01:05–05:25 (good, 4.33 h)	42.9° 02:05	11.05	86%	70.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-10-20&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.