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: 09-04 (17), 09-03 (15), 09-02 (14), 09-01 (11), 08-31 (10) — by astronomy; check the weather when the night is within four days.

2035-08-06astronomy score per night — click a bar for that night2035-09-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-08-06 Mon	0	—	unknown	—	42.9° 09:55	6.12	13%	94.5°
2035-08-07 Tue	0	—	unknown	—	42.9° 09:50	6.17	22%	106.8°
2035-08-08 Wed	0	—	unknown	—	42.9° 09:50	6.23	31%	118.5°
2035-08-09 Thu	0	—	unknown	—	42.9° 09:45	6.29	40%	129.5°
2035-08-10 Fri	0	—	unknown	—	42.9° 09:40	6.34	50%	139.6°
2035-08-11 Sat	0	—	unknown	—	42.9° 09:35	6.4	60%	148.3°
2035-08-12 Sun	0	—	unknown	—	42.9° 09:30	6.46	69%	154.5°
2035-08-13 Mon	0	—	unknown	—	42.9° 09:30	6.52	77%	156.3°
2035-08-14 Tue	0	—	unknown	—	42.9° 09:25	6.57	85%	152.8°
2035-08-15 Wed	0	—	unknown	—	42.9° 09:20	6.63	91%	145.6°
2035-08-16 Thu	0	—	unknown	—	42.9° 09:15	6.69	96%	136.4°
2035-08-17 Fri	0	—	unknown	—	42.9° 09:10	6.75	99%	126.1°
2035-08-18 Sat	0	—	unknown	—	42.9° 09:10	6.8	100%	115.2°
2035-08-19 Sun	0	—	unknown	—	42.9° 09:05	6.86	99%	103.9°
2035-08-20 Mon	0	—	unknown	—	42.9° 09:00	6.92	96%	92.2°
2035-08-21 Tue	0	—	unknown	—	42.9° 08:55	6.98	91%	80.3°
2035-08-22 Wed	0	—	unknown	—	42.9° 08:55	7.03	85%	68.4°
2035-08-23 Thu	0	—	unknown	—	42.9° 08:50	7.09	76%	56.4°
2035-08-24 Fri	1	—	unknown	—	42.9° 08:45	7.15	66%	44.8°
2035-08-25 Sat	1	—	unknown	—	42.9° 08:40	7.21	55%	34.2°
2035-08-26 Sun	2	—	unknown	04:55–05:05 (marginal, 0.17 h)	42.9° 08:35	7.26	44%	26.1°
2035-08-27 Mon	3	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.32	32%	23.8°
2035-08-28 Tue	4	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.38	22%	28.9°
2035-08-29 Wed	7	—	unknown	04:40–05:10 (marginal, 0.5 h)	42.9° 08:25	7.43	13%	38.8°
2035-08-30 Thu	8	—	unknown	04:35–05:45 (marginal, 1.17 h)	42.9° 08:20	7.49	6%	50.7°
2035-08-31 Fri	10	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:15	7.55	2%	63.4°
2035-09-01 Sat	11	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.6	0%	76.4°
2035-09-02 Sun	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.66	1%	89.2°
2035-09-03 Mon	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.71	4%	101.8°
2035-09-04 Tue	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.77	10%	113.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-08-06&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.