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: 08-25 (4), 08-24 (2), 08-20 (1), 08-21 (1), 08-22 (1) — by astronomy; check the weather when the night is within four days.

2041-07-27astronomy score per night — click a bar for that night2041-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-07-27 Sat	0	—	unknown	—	42.9° 10:35	5.6	0%	51.9°
2041-07-28 Sun	0	—	unknown	—	42.9° 10:30	5.65	1%	61.1°
2041-07-29 Mon	0	—	unknown	—	42.9° 10:25	5.7	3%	70.8°
2041-07-30 Tue	0	—	unknown	—	42.9° 10:20	5.76	8%	80.7°
2041-07-31 Wed	0	—	unknown	—	42.9° 10:15	5.81	13%	90.7°
2041-08-01 Thu	0	—	unknown	—	42.9° 10:15	5.87	20%	100.7°
2041-08-02 Fri	0	—	unknown	—	42.9° 10:10	5.92	28%	110.7°
2041-08-03 Sat	0	—	unknown	—	42.9° 10:05	5.98	38%	120.5°
2041-08-04 Sun	0	—	unknown	—	42.9° 10:00	6.03	47%	129.8°
2041-08-05 Mon	0	—	unknown	—	42.9° 10:00	6.09	57%	138.3°
2041-08-06 Tue	0	—	unknown	—	42.9° 09:55	6.15	68%	144.9°
2041-08-07 Wed	0	—	unknown	—	42.9° 09:50	6.2	77%	147.9°
2041-08-08 Thu	0	—	unknown	—	42.9° 09:45	6.26	86%	146.0°
2041-08-09 Fri	0	—	unknown	—	42.9° 09:40	6.32	93%	139.3°
2041-08-10 Sat	0	—	unknown	—	42.9° 09:40	6.38	98%	129.4°
2041-08-11 Sun	0	—	unknown	—	42.9° 09:35	6.43	100%	117.8°
2041-08-12 Mon	0	—	unknown	—	42.9° 09:30	6.49	99%	105.3°
2041-08-13 Tue	0	—	unknown	—	42.9° 09:25	6.55	95%	92.6°
2041-08-14 Wed	0	—	unknown	—	42.9° 09:20	6.61	88%	79.9°
2041-08-15 Thu	0	—	unknown	—	42.9° 09:20	6.66	79%	67.7°
2041-08-16 Fri	0	—	unknown	—	42.9° 09:15	6.72	69%	56.4°
2041-08-17 Sat	0	—	unknown	—	42.9° 09:10	6.78	59%	46.3°
2041-08-18 Sun	0	—	unknown	—	42.9° 09:05	6.84	48%	38.3°
2041-08-19 Mon	0	—	unknown	—	42.9° 09:05	6.89	38%	33.2°
2041-08-20 Tue	1	—	unknown	—	42.9° 09:00	6.95	28%	32.3°
2041-08-21 Wed	1	—	unknown	—	42.9° 08:55	7.01	20%	35.5°
2041-08-22 Thu	1	—	unknown	—	42.9° 08:50	7.07	12%	41.7°
2041-08-23 Fri	1	—	unknown	—	42.9° 08:45	7.12	7%	49.7°
2041-08-24 Sat	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.18	3%	58.7°
2041-08-25 Sun	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.24	1%	68.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-07-27&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.