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: 04-07 (3), 04-08 (3), 04-09 (2), 04-10 (2), 04-11 (1) — by astronomy; check the weather when the night is within four days.

2042-04-07astronomy score per night — click a bar for that night2042-05-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-04-07 Mon	3	—	unknown	21:00–21:15 (marginal, 0.25 h)	42.9° 17:55	7.74	95%	131.8°
2042-04-08 Tue	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.69	90%	139.3°
2042-04-09 Wed	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.63	83%	144.8°
2042-04-10 Thu	2	—	unknown	—	42.9° 17:45	7.57	75%	147.0°
2042-04-11 Fri	1	—	unknown	—	42.9° 17:40	7.52	66%	145.0°
2042-04-12 Sat	1	—	unknown	—	42.9° 17:35	7.46	56%	139.2°
2042-04-13 Sun	1	—	unknown	—	42.9° 17:30	7.4	45%	130.8°
2042-04-14 Mon	1	—	unknown	—	42.9° 17:25	7.34	34%	120.7°
2042-04-15 Tue	0	—	unknown	—	42.9° 17:25	7.29	24%	109.3°
2042-04-16 Wed	0	—	unknown	—	42.9° 17:20	7.23	14%	97.3°
2042-04-17 Thu	0	—	unknown	—	42.9° 17:15	7.17	7%	84.8°
2042-04-18 Fri	0	—	unknown	—	42.9° 17:10	7.11	2%	72.3°
2042-04-19 Sat	0	—	unknown	—	42.9° 17:05	7.05	0%	60.1°
2042-04-20 Sun	0	—	unknown	—	42.9° 17:05	7.0	1%	49.0°
2042-04-21 Mon	0	—	unknown	—	42.9° 17:00	6.94	5%	39.9°
2042-04-22 Tue	0	—	unknown	—	42.9° 16:55	6.88	11%	34.2°
2042-04-23 Wed	0	—	unknown	—	42.9° 16:50	6.82	19%	33.3°
2042-04-24 Thu	0	—	unknown	—	42.9° 16:45	6.76	28%	37.1°
2042-04-25 Fri	0	—	unknown	—	42.9° 16:45	6.71	38%	44.1°
2042-04-26 Sat	0	—	unknown	—	42.9° 16:40	6.65	48%	52.7°
2042-04-27 Sun	0	—	unknown	—	42.9° 16:35	6.59	58%	62.0°
2042-04-28 Mon	0	—	unknown	—	42.9° 16:30	6.53	68%	71.7°
2042-04-29 Tue	0	—	unknown	—	42.9° 16:30	6.47	76%	81.6°
2042-04-30 Wed	0	—	unknown	—	42.9° 16:25	6.41	84%	91.5°
2042-05-01 Thu	0	—	unknown	—	42.9° 16:20	6.36	90%	101.4°
2042-05-02 Fri	0	—	unknown	—	42.9° 16:15	6.3	95%	111.2°
2042-05-03 Sat	0	—	unknown	—	42.9° 16:10	6.24	98%	120.6°
2042-05-04 Sun	0	—	unknown	—	42.9° 16:10	6.18	100%	129.6°
2042-05-05 Mon	0	—	unknown	—	42.9° 16:05	6.13	100%	137.6°
2042-05-06 Tue	0	—	unknown	—	42.9° 16:00	6.07	97%	143.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-07&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.