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.

2027-04-28astronomy score per night — click a bar for that night2027-05-27

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-28 Wed	—	unknown	—	42.9° 16:30	6.55	49%	126.9°
2027-04-29 Thu	—	unknown	—	42.9° 16:30	6.49	40%	117.7°
2027-04-30 Fri	—	unknown	—	42.9° 16:25	6.43	31%	107.9°
2027-05-01 Sat	—	unknown	—	42.9° 16:20	6.38	22%	97.7°
2027-05-02 Sun	—	unknown	—	42.9° 16:15	6.32	14%	87.1°
2027-05-03 Mon	—	unknown	—	42.9° 16:15	6.26	8%	76.2°
2027-05-04 Tue	—	unknown	—	42.9° 16:10	6.2	3%	65.2°
2027-05-05 Wed	—	unknown	—	42.9° 16:05	6.15	0%	54.6°
2027-05-06 Thu	—	unknown	—	42.9° 16:00	6.09	0%	44.7°
2027-05-07 Fri	—	unknown	—	42.9° 15:55	6.03	3%	36.9°
2027-05-08 Sat	—	unknown	—	42.9° 15:55	5.98	8%	32.8°
2027-05-09 Sun	—	unknown	—	42.9° 15:50	5.92	16%	34.1°
2027-05-10 Mon	—	unknown	—	42.9° 15:45	5.86	25%	40.3°
2027-05-11 Tue	—	unknown	—	42.9° 15:40	5.81	36%	49.4°
2027-05-12 Wed	—	unknown	—	42.9° 15:35	5.75	47%	60.0°
2027-05-13 Thu	—	unknown	—	42.9° 15:35	5.7	58%	71.3°
2027-05-14 Fri	—	unknown	—	42.9° 15:30	5.64	69%	82.8°
2027-05-15 Sat	—	unknown	—	42.9° 15:25	5.59	79%	94.3°
2027-05-16 Sun	—	unknown	—	42.9° 15:20	5.54	87%	105.5°
2027-05-17 Mon	—	unknown	—	42.9° 15:20	5.48	93%	116.4°
2027-05-18 Tue	—	unknown	—	42.9° 15:15	5.43	97%	126.4°
2027-05-19 Wed	—	unknown	—	42.9° 15:10	5.38	100%	135.4°
2027-05-20 Thu	—	unknown	—	42.9° 15:05	5.33	100%	142.5°
2027-05-21 Fri	—	unknown	—	42.9° 15:00	5.28	98%	146.7°
2027-05-22 Sat	—	unknown	—	42.9° 15:00	5.23	94%	147.1°
2027-05-23 Sun	—	unknown	—	42.9° 14:55	5.19	89%	143.8°
2027-05-24 Mon	—	unknown	—	42.9° 14:50	5.14	82%	137.7°
2027-05-25 Tue	—	unknown	—	42.9° 14:45	5.09	74%	129.8°
2027-05-26 Wed	—	unknown	—	42.9° 14:40	5.05	66%	120.9°
2027-05-27 Thu	—	unknown	—	42.9° 14:40	5.0	56%	111.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-28&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.