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: 04-03 (4), 04-04 (2), 04-05 (2), 04-06 (2), 04-07 (2) — by astronomy; check the weather when the night is within four days.

2047-04-03astronomy score per night — click a bar for that night2047-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-04-03 Wed	4	—	unknown	21:25–21:50 (marginal, 0.42 h)	42.9° 18:10	7.98	53%	37.4°
2047-04-04 Thu	2	—	unknown	21:30–21:40 (marginal, 0.17 h)	42.9° 18:05	7.92	63%	45.4°
2047-04-05 Fri	2	—	unknown	21:30–21:35 (marginal, 0.08 h)	42.9° 18:05	7.87	74%	55.5°
2047-04-06 Sat	2	—	unknown	21:30–21:35 (marginal, 0.08 h)	42.9° 18:00	7.81	83%	66.8°
2047-04-07 Sun	2	—	unknown	—	42.9° 17:55	7.75	91%	79.0°
2047-04-08 Mon	1	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.7	96%	91.7°
2047-04-09 Tue	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.64	99%	104.7°
2047-04-10 Wed	1	—	unknown	—	42.9° 17:45	7.58	99%	117.4°
2047-04-11 Thu	1	—	unknown	—	42.9° 17:40	7.53	96%	129.4°
2047-04-12 Fri	1	—	unknown	—	42.9° 17:35	7.47	91%	139.7°
2047-04-13 Sat	1	—	unknown	—	42.9° 17:30	7.41	83%	146.9°
2047-04-14 Sun	1	—	unknown	—	42.9° 17:30	7.36	73%	149.1°
2047-04-15 Mon	0	—	unknown	—	42.9° 17:25	7.3	63%	145.9°
2047-04-16 Tue	0	—	unknown	—	42.9° 17:20	7.24	52%	138.9°
2047-04-17 Wed	0	—	unknown	—	42.9° 17:15	7.18	42%	129.9°
2047-04-18 Thu	0	—	unknown	—	42.9° 17:10	7.12	32%	120.1°
2047-04-19 Fri	0	—	unknown	—	42.9° 17:10	7.07	23%	110.0°
2047-04-20 Sat	0	—	unknown	—	42.9° 17:05	7.01	16%	99.7°
2047-04-21 Sun	0	—	unknown	—	42.9° 17:00	6.95	10%	89.5°
2047-04-22 Mon	0	—	unknown	—	42.9° 16:55	6.89	5%	79.3°
2047-04-23 Tue	0	—	unknown	—	42.9° 16:50	6.83	2%	69.3°
2047-04-24 Wed	0	—	unknown	—	42.9° 16:50	6.78	0%	59.6°
2047-04-25 Thu	0	—	unknown	—	42.9° 16:45	6.72	1%	50.3°
2047-04-26 Fri	0	—	unknown	—	42.9° 16:40	6.66	3%	42.0°
2047-04-27 Sat	0	—	unknown	—	42.9° 16:35	6.6	7%	35.3°
2047-04-28 Sun	0	—	unknown	—	42.9° 16:35	6.54	12%	31.3°
2047-04-29 Mon	0	—	unknown	—	42.9° 16:30	6.48	19%	31.3°
2047-04-30 Tue	0	—	unknown	—	42.9° 16:25	6.43	28%	35.4°
2047-05-01 Wed	0	—	unknown	—	42.9° 16:20	6.37	37%	42.7°
2047-05-02 Thu	0	—	unknown	—	42.9° 16:15	6.31	48%	52.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-04-03&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.