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 (1), 04-11 (1) — by astronomy; check the weather when the night is within four days.

2046-04-07astronomy score per night — click a bar for that night2046-05-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-04-07 Sat	3	—	unknown	21:00–21:15 (marginal, 0.25 h)	42.9° 17:55	7.74	2%	57.6°
2046-04-08 Sun	3	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.68	6%	48.5°
2046-04-09 Mon	2	—	unknown	—	42.9° 17:45	7.63	11%	40.5°
2046-04-10 Tue	1	—	unknown	—	42.9° 17:45	7.57	18%	34.7°
2046-04-11 Wed	1	—	unknown	—	42.9° 17:40	7.51	27%	32.4°
2046-04-12 Thu	0	—	unknown	—	42.9° 17:35	7.46	37%	34.6°
2046-04-13 Fri	0	—	unknown	—	42.9° 17:30	7.4	48%	40.8°
2046-04-14 Sat	0	—	unknown	—	42.9° 17:25	7.34	59%	49.8°
2046-04-15 Sun	0	—	unknown	—	42.9° 17:25	7.28	70%	60.5°
2046-04-16 Mon	0	—	unknown	—	42.9° 17:20	7.23	80%	72.2°
2046-04-17 Tue	0	—	unknown	—	42.9° 17:15	7.17	88%	84.6°
2046-04-18 Wed	0	—	unknown	—	42.9° 17:10	7.11	95%	97.2°
2046-04-19 Thu	0	—	unknown	—	42.9° 17:05	7.05	99%	109.7°
2046-04-20 Fri	0	—	unknown	—	42.9° 17:05	6.99	100%	121.6°
2046-04-21 Sat	0	—	unknown	—	42.9° 17:00	6.94	98%	132.4°
2046-04-22 Sun	0	—	unknown	—	42.9° 16:55	6.88	94%	141.2°
2046-04-23 Mon	0	—	unknown	—	42.9° 16:50	6.82	87%	146.6°
2046-04-24 Tue	0	—	unknown	—	42.9° 16:50	6.76	79%	147.5°
2046-04-25 Wed	0	—	unknown	—	42.9° 16:45	6.7	70%	143.8°
2046-04-26 Thu	0	—	unknown	—	42.9° 16:40	6.64	60%	137.2°
2046-04-27 Fri	0	—	unknown	—	42.9° 16:35	6.59	50%	128.8°
2046-04-28 Sat	0	—	unknown	—	42.9° 16:30	6.53	41%	119.6°
2046-04-29 Sun	0	—	unknown	—	42.9° 16:30	6.47	32%	110.0°
2046-04-30 Mon	0	—	unknown	—	42.9° 16:25	6.41	23%	100.2°
2046-05-01 Tue	0	—	unknown	—	42.9° 16:20	6.35	16%	90.2°
2046-05-02 Wed	0	—	unknown	—	42.9° 16:15	6.3	10%	80.2°
2046-05-03 Thu	0	—	unknown	—	42.9° 16:10	6.24	5%	70.1°
2046-05-04 Fri	0	—	unknown	—	42.9° 16:10	6.18	2%	60.3°
2046-05-05 Sat	0	—	unknown	—	42.9° 16:05	6.12	0%	50.9°
2046-05-06 Sun	0	—	unknown	—	42.9° 16:00	6.07	1%	42.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-04-07&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.