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: 03-25 (24), 03-26 (22), 03-27 (19), 03-28 (16), 03-29 (13) — by astronomy; check the weather when the night is within four days.

2039-03-25astronomy score per night — click a bar for that night2039-04-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-03-25 Fri	24	—	unknown	20:15–21:05 (good, 0.83 h)	42.9° 17:45	8.47	2%	65.3°
2039-03-26 Sat	22	—	unknown	20:15–21:00 (good, 0.75 h)	42.9° 17:40	8.42	5%	55.1°
2039-03-27 Sun	19	—	unknown	21:20–21:55 (good, 0.58 h)	42.9° 18:40	8.36	10%	45.7°
2039-03-28 Mon	16	—	unknown	21:20–21:45 (good, 0.42 h)	42.9° 18:35	8.31	16%	37.4°
2039-03-29 Tue	13	—	unknown	21:20–21:35 (good, 0.25 h)	42.9° 18:30	8.25	23%	31.2°
2039-03-30 Wed	10	—	unknown	20:45–22:15 (marginal, 1.5 h)	42.9° 18:25	8.2	32%	28.4°
2039-03-31 Thu	7	—	unknown	21:25–22:10 (marginal, 0.75 h)	42.9° 18:25	8.15	41%	30.0°
2039-04-01 Fri	5	—	unknown	21:25–22:00 (marginal, 0.58 h)	42.9° 18:20	8.09	50%	35.4°
2039-04-02 Sat	4	—	unknown	21:25–21:50 (marginal, 0.42 h)	42.9° 18:15	8.04	60%	43.4°
2039-04-03 Sun	3	—	unknown	21:25–21:40 (marginal, 0.25 h)	42.9° 18:10	7.98	70%	53.1°
2039-04-04 Mon	2	—	unknown	21:30–21:40 (marginal, 0.17 h)	42.9° 18:05	7.93	79%	63.8°
2039-04-05 Tue	2	—	unknown	21:30–21:40 (marginal, 0.17 h)	42.9° 18:05	7.87	87%	75.4°
2039-04-06 Wed	2	—	unknown	21:30–21:45 (marginal, 0.25 h)	42.9° 18:00	7.81	93%	87.5°
2039-04-07 Thu	2	—	unknown	21:35–21:45 (marginal, 0.17 h)	42.9° 17:55	7.76	98%	100.0°
2039-04-08 Fri	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:50	7.7	100%	112.7°
2039-04-09 Sat	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	42.9° 17:45	7.64	99%	125.1°
2039-04-10 Sun	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.59	95%	136.7°
2039-04-11 Mon	1	—	unknown	—	42.9° 17:40	7.53	89%	146.1°
2039-04-12 Tue	1	—	unknown	—	42.9° 17:35	7.47	80%	151.2°
2039-04-13 Wed	1	—	unknown	—	42.9° 17:30	7.42	70%	150.0°
2039-04-14 Thu	1	—	unknown	—	42.9° 17:30	7.36	59%	143.4°
2039-04-15 Fri	0	—	unknown	—	42.9° 17:25	7.3	48%	133.9°
2039-04-16 Sat	0	—	unknown	—	42.9° 17:20	7.24	37%	123.3°
2039-04-17 Sun	0	—	unknown	—	42.9° 17:15	7.19	27%	112.2°
2039-04-18 Mon	0	—	unknown	—	42.9° 17:10	7.13	19%	101.0°
2039-04-19 Tue	0	—	unknown	—	42.9° 17:10	7.07	12%	89.9°
2039-04-20 Wed	0	—	unknown	—	42.9° 17:05	7.01	6%	78.9°
2039-04-21 Thu	0	—	unknown	—	42.9° 17:00	6.95	2%	68.2°
2039-04-22 Fri	0	—	unknown	—	42.9° 16:55	6.9	0%	58.0°
2039-04-23 Sat	0	—	unknown	—	42.9° 16:50	6.84	0%	48.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-03-25&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.