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: 04-08 (3), 04-09 (3), 04-10 (2), 04-11 (1), 04-12 (1) — by astronomy; check the weather when the night is within four days.

2043-04-08astronomy score per night — click a bar for that night2043-05-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-04-08 Wed	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.7	1%	77.7°
2043-04-09 Thu	3	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:45	7.64	0%	65.6°
2043-04-10 Fri	2	—	unknown	—	42.9° 17:45	7.59	2%	54.0°
2043-04-11 Sat	1	—	unknown	—	42.9° 17:40	7.53	7%	43.9°
2043-04-12 Sun	1	—	unknown	—	42.9° 17:35	7.47	14%	36.6°
2043-04-13 Mon	1	—	unknown	—	42.9° 17:30	7.41	23%	33.8°
2043-04-14 Tue	0	—	unknown	—	42.9° 17:30	7.36	34%	36.1°
2043-04-15 Wed	0	—	unknown	—	42.9° 17:25	7.3	45%	42.5°
2043-04-16 Thu	0	—	unknown	—	42.9° 17:20	7.24	55%	51.1°
2043-04-17 Fri	0	—	unknown	—	42.9° 17:15	7.18	66%	60.7°
2043-04-18 Sat	0	—	unknown	—	42.9° 17:10	7.13	75%	70.8°
2043-04-19 Sun	0	—	unknown	—	42.9° 17:10	7.07	83%	81.0°
2043-04-20 Mon	0	—	unknown	—	42.9° 17:05	7.01	90%	91.2°
2043-04-21 Tue	0	—	unknown	—	42.9° 17:00	6.95	95%	101.3°
2043-04-22 Wed	0	—	unknown	—	42.9° 16:55	6.89	98%	111.1°
2043-04-23 Thu	0	—	unknown	—	42.9° 16:50	6.84	100%	120.4°
2043-04-24 Fri	0	—	unknown	—	42.9° 16:50	6.78	100%	129.2°
2043-04-25 Sat	0	—	unknown	—	42.9° 16:45	6.72	98%	136.8°
2043-04-26 Sun	0	—	unknown	—	42.9° 16:40	6.66	94%	142.7°
2043-04-27 Mon	0	—	unknown	—	42.9° 16:35	6.6	88%	146.0°
2043-04-28 Tue	0	—	unknown	—	42.9° 16:35	6.54	82%	145.7°
2043-04-29 Wed	0	—	unknown	—	42.9° 16:30	6.49	74%	141.9°
2043-04-30 Thu	0	—	unknown	—	42.9° 16:25	6.43	64%	135.3°
2043-05-01 Fri	0	—	unknown	—	42.9° 16:20	6.37	55%	126.8°
2043-05-02 Sat	0	—	unknown	—	42.9° 16:15	6.31	44%	117.1°
2043-05-03 Sun	0	—	unknown	—	42.9° 16:15	6.25	34%	106.4°
2043-05-04 Mon	0	—	unknown	—	42.9° 16:10	6.2	24%	95.0°
2043-05-05 Tue	0	—	unknown	—	42.9° 16:05	6.14	15%	83.2°
2043-05-06 Wed	0	—	unknown	—	42.9° 16:00	6.08	7%	71.1°
2043-05-07 Thu	0	—	unknown	—	42.9° 15:55	6.03	2%	59.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-04-08&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.