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.

2043-04-17astronomy score per night — click a bar for that night2043-05-16

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-04-17 Fri	—	unknown	—	42.9° 17:15	7.18	66%	60.7°
2043-04-18 Sat	—	unknown	—	42.9° 17:10	7.13	75%	70.8°
2043-04-19 Sun	—	unknown	—	42.9° 17:10	7.07	83%	81.0°
2043-04-20 Mon	—	unknown	—	42.9° 17:05	7.01	90%	91.2°
2043-04-21 Tue	—	unknown	—	42.9° 17:00	6.95	95%	101.3°
2043-04-22 Wed	—	unknown	—	42.9° 16:55	6.89	98%	111.1°
2043-04-23 Thu	—	unknown	—	42.9° 16:50	6.84	100%	120.4°
2043-04-24 Fri	—	unknown	—	42.9° 16:50	6.78	100%	129.2°
2043-04-25 Sat	—	unknown	—	42.9° 16:45	6.72	98%	136.8°
2043-04-26 Sun	—	unknown	—	42.9° 16:40	6.66	94%	142.7°
2043-04-27 Mon	—	unknown	—	42.9° 16:35	6.6	88%	146.0°
2043-04-28 Tue	—	unknown	—	42.9° 16:35	6.54	82%	145.7°
2043-04-29 Wed	—	unknown	—	42.9° 16:30	6.49	74%	141.9°
2043-04-30 Thu	—	unknown	—	42.9° 16:25	6.43	64%	135.3°
2043-05-01 Fri	—	unknown	—	42.9° 16:20	6.37	55%	126.8°
2043-05-02 Sat	—	unknown	—	42.9° 16:15	6.31	44%	117.1°
2043-05-03 Sun	—	unknown	—	42.9° 16:15	6.25	34%	106.4°
2043-05-04 Mon	—	unknown	—	42.9° 16:10	6.2	24%	95.0°
2043-05-05 Tue	—	unknown	—	42.9° 16:05	6.14	15%	83.2°
2043-05-06 Wed	—	unknown	—	42.9° 16:00	6.08	7%	71.1°
2043-05-07 Thu	—	unknown	—	42.9° 15:55	6.03	2%	59.2°
2043-05-08 Fri	—	unknown	—	42.9° 15:55	5.97	0%	48.2°
2043-05-09 Sat	—	unknown	—	42.9° 15:50	5.91	1%	39.3°
2043-05-10 Sun	—	unknown	—	42.9° 15:45	5.86	5%	34.2°
2043-05-11 Mon	—	unknown	—	42.9° 15:40	5.8	12%	34.6°
2043-05-12 Tue	—	unknown	—	42.9° 15:40	5.75	20%	39.9°
2043-05-13 Wed	—	unknown	—	42.9° 15:35	5.69	30%	48.1°
2043-05-14 Thu	—	unknown	—	42.9° 15:30	5.64	40%	57.8°
2043-05-15 Fri	—	unknown	—	42.9° 15:25	5.58	50%	68.0°
2043-05-16 Sat	—	unknown	—	42.9° 15:20	5.53	61%	78.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-04-17&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.