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: 03-09 (51), 03-10 (50), 03-11 (47), 03-12 (43), 03-13 (37) — by astronomy; check the weather when the night is within four days.

2035-03-09astronomy score per night — click a bar for that night2035-04-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-03-09 Fri	51	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.28	0%	93.4°
2035-03-10 Sat	50	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.23	1%	80.9°
2035-03-11 Sun	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.18	5%	68.2°
2035-03-12 Mon	43	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.13	11%	55.7°
2035-03-13 Tue	37	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:35	9.09	19%	43.6°
2035-03-14 Wed	29	—	unknown	20:00–21:30 (good, 1.5 h)	42.9° 18:30	9.04	29%	32.8°
2035-03-15 Thu	22	—	unknown	20:05–21:05 (good, 1.0 h)	42.9° 18:25	8.99	40%	25.2°
2035-03-16 Fri	15	—	unknown	20:05–22:05 (marginal, 2.0 h)	42.9° 18:20	8.94	51%	23.9°
2035-03-17 Sat	11	—	unknown	20:05–21:45 (marginal, 1.67 h)	42.9° 18:20	8.88	62%	29.7°
2035-03-18 Sun	9	—	unknown	20:05–21:35 (marginal, 1.5 h)	42.9° 18:15	8.83	73%	39.5°
2035-03-19 Mon	9	—	unknown	20:05–21:30 (marginal, 1.42 h)	42.9° 18:10	8.78	82%	51.0°
2035-03-20 Tue	9	—	unknown	20:10–21:30 (marginal, 1.33 h)	42.9° 18:05	8.73	90%	63.1°
2035-03-21 Wed	11	—	unknown	20:10–21:35 (marginal, 1.42 h)	42.9° 18:00	8.68	96%	75.3°
2035-03-22 Thu	14	—	unknown	20:10–21:40 (marginal, 1.5 h)	42.9° 18:00	8.63	99%	87.5°
2035-03-23 Fri	17	—	unknown	20:10–20:45 (good, 0.58 h)	42.9° 17:55	8.58	100%	99.6°
2035-03-24 Sat	19	—	unknown	20:15–20:55 (good, 0.67 h)	42.9° 17:50	8.52	99%	111.3°
2035-03-25 Sun	23	—	unknown	21:15–21:55 (good, 0.67 h)	42.9° 18:45	8.47	96%	122.6°
2035-03-26 Mon	22	—	unknown	21:15–22:00 (good, 0.75 h)	42.9° 18:40	8.42	91%	133.2°
2035-03-27 Tue	21	—	unknown	21:20–22:00 (good, 0.67 h)	42.9° 18:40	8.36	85%	142.9°
2035-03-28 Wed	19	—	unknown	21:20–21:55 (good, 0.58 h)	42.9° 18:35	8.31	77%	151.0°
2035-03-29 Thu	17	—	unknown	21:20–21:50 (good, 0.5 h)	42.9° 18:30	8.26	69%	155.9°
2035-03-30 Fri	15	—	unknown	21:20–21:45 (good, 0.42 h)	42.9° 18:25	8.2	60%	155.8°
2035-03-31 Sat	13	—	unknown	21:25–21:40 (good, 0.25 h)	42.9° 18:25	8.15	50%	150.7°
2035-04-01 Sun	12	—	unknown	21:25–21:40 (good, 0.25 h)	42.9° 18:20	8.09	41%	142.6°
2035-04-02 Mon	10	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:15	8.04	31%	132.8°
2035-04-03 Tue	9	—	unknown	21:25–21:30 (good, 0.08 h)	42.9° 18:10	7.98	22%	122.0°
2035-04-04 Wed	7	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.93	14%	110.5°
2035-04-05 Thu	6	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.87	8%	98.4°
2035-04-06 Fri	5	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.82	3%	85.9°
2035-04-07 Sat	4	—	unknown	20:55–21:15 (marginal, 0.33 h)	42.9° 17:55	7.76	0%	73.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-03-09&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.