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: 09-13 (32), 09-12 (30), 09-11 (29), 09-10 (27), 09-09 (25) — by astronomy; check the weather when the night is within four days.

2035-08-15astronomy score per night — click a bar for that night2035-09-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2035-09-05 Wed	18	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.82	17%	125.5°
2035-09-06 Thu	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.88	25%	136.1°
2035-09-07 Fri	22	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.93	34%	145.6°
2035-09-08 Sat	24	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:45	7.99	43%	152.9°
2035-09-09 Sun	25	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:40	8.04	53%	156.3°
2035-09-10 Mon	27	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.1	62%	154.4°
2035-09-11 Tue	29	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.15	71%	148.2°
2035-09-12 Wed	30	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.2	80%	139.5°
2035-09-13 Thu	32	—	unknown	04:10–05:25 (good, 1.25 h)	42.9° 07:25	8.26	87%	129.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-08-15&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.