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.

2035-04-18astronomy score per night — click a bar for that night2035-05-17

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-04-18 Wed	—	unknown	—	42.9° 17:10	7.13	87%	84.2°
2035-04-19 Thu	—	unknown	—	42.9° 17:10	7.07	93%	96.1°
2035-04-20 Fri	—	unknown	—	42.9° 17:05	7.01	97%	107.8°
2035-04-21 Sat	—	unknown	—	42.9° 17:00	6.96	100%	119.1°
2035-04-22 Sun	—	unknown	—	42.9° 16:55	6.9	100%	129.9°
2035-04-23 Mon	—	unknown	—	42.9° 16:50	6.84	98%	139.9°
2035-04-24 Tue	—	unknown	—	42.9° 16:50	6.78	94%	148.6°
2035-04-25 Wed	—	unknown	—	42.9° 16:45	6.72	90%	154.7°
2035-04-26 Thu	—	unknown	—	42.9° 16:40	6.67	83%	156.2°
2035-04-27 Fri	—	unknown	—	42.9° 16:35	6.61	75%	152.6°
2035-04-28 Sat	—	unknown	—	42.9° 16:35	6.55	67%	145.3°
2035-04-29 Sun	—	unknown	—	42.9° 16:30	6.49	57%	136.1°
2035-04-30 Mon	—	unknown	—	42.9° 16:25	6.43	48%	125.8°
2035-05-01 Tue	—	unknown	—	42.9° 16:20	6.37	38%	114.8°
2035-05-02 Wed	—	unknown	—	42.9° 16:15	6.32	28%	103.2°
2035-05-03 Thu	—	unknown	—	42.9° 16:15	6.26	19%	91.1°
2035-05-04 Fri	—	unknown	—	42.9° 16:10	6.2	11%	78.6°
2035-05-05 Sat	—	unknown	—	42.9° 16:05	6.14	5%	65.8°
2035-05-06 Sun	—	unknown	—	42.9° 16:00	6.09	1%	52.9°
2035-05-07 Mon	—	unknown	—	42.9° 15:55	6.03	0%	40.6°
2035-05-08 Tue	—	unknown	—	42.9° 15:55	5.97	2%	30.0°
2035-05-09 Wed	—	unknown	—	42.9° 15:50	5.92	7%	24.0°
2035-05-10 Thu	—	unknown	—	42.9° 15:45	5.86	14%	26.0°
2035-05-11 Fri	—	unknown	—	42.9° 15:40	5.81	23%	34.4°
2035-05-12 Sat	—	unknown	—	42.9° 15:40	5.75	33%	45.4°
2035-05-13 Sun	—	unknown	—	42.9° 15:35	5.7	44%	57.4°
2035-05-14 Mon	—	unknown	—	42.9° 15:30	5.64	55%	69.5°
2035-05-15 Tue	—	unknown	—	42.9° 15:25	5.59	66%	81.6°
2035-05-16 Wed	—	unknown	—	42.9° 15:20	5.53	75%	93.4°
2035-05-17 Thu	—	unknown	—	42.9° 15:20	5.48	83%	105.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-04-18&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.