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: 04-05 (6), 04-06 (5), 04-07 (4), 04-08 (3), 04-09 (2) — by astronomy; check the weather when the night is within four days.

2035-04-05astronomy score per night — click a bar for that night2035-05-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2035-04-08 Sun	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.7	0%	60.2°
2035-04-09 Mon	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.65	3%	47.6°
2035-04-10 Tue	1	—	unknown	—	42.9° 17:45	7.59	8%	36.0°
2035-04-11 Wed	1	—	unknown	—	42.9° 17:40	7.53	16%	26.9°
2035-04-12 Thu	1	—	unknown	—	42.9° 17:35	7.48	26%	23.6°
2035-04-13 Fri	0	—	unknown	—	42.9° 17:30	7.42	37%	27.9°
2035-04-14 Sat	0	—	unknown	—	42.9° 17:30	7.36	48%	37.2°
2035-04-15 Sun	0	—	unknown	—	42.9° 17:25	7.3	59%	48.3°
2035-04-16 Mon	0	—	unknown	—	42.9° 17:20	7.25	70%	60.2°
2035-04-17 Tue	0	—	unknown	—	42.9° 17:15	7.19	79%	72.2°
2035-04-18 Wed	0	—	unknown	—	42.9° 17:10	7.13	87%	84.2°
2035-04-19 Thu	0	—	unknown	—	42.9° 17:10	7.07	93%	96.1°
2035-04-20 Fri	0	—	unknown	—	42.9° 17:05	7.01	97%	107.8°
2035-04-21 Sat	0	—	unknown	—	42.9° 17:00	6.96	100%	119.1°
2035-04-22 Sun	0	—	unknown	—	42.9° 16:55	6.9	100%	129.9°
2035-04-23 Mon	0	—	unknown	—	42.9° 16:50	6.84	98%	139.9°
2035-04-24 Tue	0	—	unknown	—	42.9° 16:50	6.78	94%	148.6°
2035-04-25 Wed	0	—	unknown	—	42.9° 16:45	6.72	90%	154.7°
2035-04-26 Thu	0	—	unknown	—	42.9° 16:40	6.67	83%	156.2°
2035-04-27 Fri	0	—	unknown	—	42.9° 16:35	6.61	75%	152.6°
2035-04-28 Sat	0	—	unknown	—	42.9° 16:35	6.55	67%	145.3°
2035-04-29 Sun	0	—	unknown	—	42.9° 16:30	6.49	57%	136.1°
2035-04-30 Mon	0	—	unknown	—	42.9° 16:25	6.43	48%	125.8°
2035-05-01 Tue	0	—	unknown	—	42.9° 16:20	6.37	38%	114.8°
2035-05-02 Wed	0	—	unknown	—	42.9° 16:15	6.32	28%	103.2°
2035-05-03 Thu	0	—	unknown	—	42.9° 16:15	6.26	19%	91.1°
2035-05-04 Fri	0	—	unknown	—	42.9° 16:10	6.2	11%	78.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-04-05&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.