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: 08-27 (3), 08-26 (2), 08-24 (1), 08-25 (1) — by astronomy; check the weather when the night is within four days.

2035-07-29astronomy score per night — click a bar for that night2035-08-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-07-29 Sun	0	—	unknown	—	42.9° 10:25	5.67	30%	31.8°
2035-07-30 Mon	0	—	unknown	—	42.9° 10:25	5.73	20%	24.7°
2035-07-31 Tue	0	—	unknown	—	42.9° 10:20	5.78	11%	24.7°
2035-08-01 Wed	0	—	unknown	—	42.9° 10:15	5.84	5%	32.1°
2035-08-02 Thu	0	—	unknown	—	42.9° 10:10	5.89	1%	43.2°
2035-08-03 Fri	0	—	unknown	—	42.9° 10:05	5.95	0%	55.8°
2035-08-04 Sat	0	—	unknown	—	42.9° 10:05	6.0	2%	68.8°
2035-08-05 Sun	0	—	unknown	—	42.9° 10:00	6.06	7%	81.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-07-29&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.