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: 04-10 (2), 04-11 (1), 04-12 (1), 04-13 (1), 04-14 (1) — by astronomy; check the weather when the night is within four days.

2034-04-10astronomy score per night — click a bar for that night2034-05-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-04-10 Mon	2	—	unknown	—	42.9° 17:40	7.58	60%	151.9°
2034-04-11 Tue	1	—	unknown	—	42.9° 17:40	7.52	50%	143.8°
2034-04-12 Wed	1	—	unknown	—	42.9° 17:35	7.46	40%	133.6°
2034-04-13 Thu	1	—	unknown	—	42.9° 17:30	7.4	30%	122.2°
2034-04-14 Fri	1	—	unknown	—	42.9° 17:25	7.35	20%	109.9°
2034-04-15 Sat	0	—	unknown	—	42.9° 17:25	7.29	12%	96.9°
2034-04-16 Sun	0	—	unknown	—	42.9° 17:20	7.23	5%	83.4°
2034-04-17 Mon	0	—	unknown	—	42.9° 17:15	7.17	1%	69.8°
2034-04-18 Tue	0	—	unknown	—	42.9° 17:10	7.12	0%	56.2°
2034-04-19 Wed	0	—	unknown	—	42.9° 17:05	7.06	2%	43.2°
2034-04-20 Thu	0	—	unknown	—	42.9° 17:05	7.0	7%	32.0°
2034-04-21 Fri	0	—	unknown	—	42.9° 17:00	6.94	14%	24.6°
2034-04-22 Sat	0	—	unknown	—	42.9° 16:55	6.88	23%	24.5°
2034-04-23 Sun	0	—	unknown	—	42.9° 16:50	6.83	33%	31.1°
2034-04-24 Mon	0	—	unknown	—	42.9° 16:45	6.77	44%	40.9°
2034-04-25 Tue	0	—	unknown	—	42.9° 16:45	6.71	55%	51.8°
2034-04-26 Wed	0	—	unknown	—	42.9° 16:40	6.65	65%	63.1°
2034-04-27 Thu	0	—	unknown	—	42.9° 16:35	6.59	74%	74.4°
2034-04-28 Fri	0	—	unknown	—	42.9° 16:30	6.53	82%	85.6°
2034-04-29 Sat	0	—	unknown	—	42.9° 16:30	6.48	89%	96.7°
2034-04-30 Sun	0	—	unknown	—	42.9° 16:25	6.42	94%	107.6°
2034-05-01 Mon	0	—	unknown	—	42.9° 16:20	6.36	98%	118.3°
2034-05-02 Tue	0	—	unknown	—	42.9° 16:15	6.3	100%	128.7°
2034-05-03 Wed	0	—	unknown	—	42.9° 16:10	6.24	100%	138.5°
2034-05-04 Thu	0	—	unknown	—	42.9° 16:10	6.19	98%	147.3°
2034-05-05 Fri	0	—	unknown	—	42.9° 16:05	6.13	95%	153.9°
2034-05-06 Sat	0	—	unknown	—	42.9° 16:00	6.07	90%	156.4°
2034-05-07 Sun	0	—	unknown	—	42.9° 15:55	6.02	83%	153.4°
2034-05-08 Mon	0	—	unknown	—	42.9° 15:50	5.96	75%	146.1°
2034-05-09 Tue	0	—	unknown	—	42.9° 15:50	5.9	66%	136.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-04-10&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.