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.

2042-04-28astronomy score per night — click a bar for that night2042-05-27

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-04-28 Mon	—	unknown	—	42.9° 16:30	6.53	68%	71.7°
2042-04-29 Tue	—	unknown	—	42.9° 16:30	6.47	76%	81.6°
2042-04-30 Wed	—	unknown	—	42.9° 16:25	6.41	84%	91.5°
2042-05-01 Thu	—	unknown	—	42.9° 16:20	6.36	90%	101.4°
2042-05-02 Fri	—	unknown	—	42.9° 16:15	6.3	95%	111.2°
2042-05-03 Sat	—	unknown	—	42.9° 16:10	6.24	98%	120.6°
2042-05-04 Sun	—	unknown	—	42.9° 16:10	6.18	100%	129.6°
2042-05-05 Mon	—	unknown	—	42.9° 16:05	6.13	100%	137.6°
2042-05-06 Tue	—	unknown	—	42.9° 16:00	6.07	97%	143.7°
2042-05-07 Wed	—	unknown	—	42.9° 15:55	6.01	93%	146.8°
2042-05-08 Thu	—	unknown	—	42.9° 15:50	5.96	87%	145.9°
2042-05-09 Fri	—	unknown	—	42.9° 15:50	5.9	79%	140.9°
2042-05-10 Sat	—	unknown	—	42.9° 15:45	5.84	70%	133.1°
2042-05-11 Sun	—	unknown	—	42.9° 15:40	5.79	60%	123.5°
2042-05-12 Mon	—	unknown	—	42.9° 15:35	5.73	49%	112.7°
2042-05-13 Tue	—	unknown	—	42.9° 15:35	5.68	37%	101.2°
2042-05-14 Wed	—	unknown	—	42.9° 15:30	5.62	27%	89.2°
2042-05-15 Thu	—	unknown	—	42.9° 15:25	5.57	17%	77.1°
2042-05-16 Fri	—	unknown	—	42.9° 15:20	5.52	9%	65.0°
2042-05-17 Sat	—	unknown	—	42.9° 15:15	5.47	3%	53.6°
2042-05-18 Sun	—	unknown	—	42.9° 15:15	5.41	0%	43.5°
2042-05-19 Mon	—	unknown	—	42.9° 15:10	5.36	0%	36.1°
2042-05-20 Tue	—	unknown	—	42.9° 15:05	5.31	3%	33.0°
2042-05-21 Wed	—	unknown	—	42.9° 15:00	5.26	8%	35.0°
2042-05-22 Thu	—	unknown	—	42.9° 14:55	5.22	15%	41.1°
2042-05-23 Fri	—	unknown	—	42.9° 14:55	5.17	23%	49.4°
2042-05-24 Sat	—	unknown	—	42.9° 14:50	5.12	32%	58.7°
2042-05-25 Sun	—	unknown	—	42.9° 14:45	5.08	42%	68.5°
2042-05-26 Mon	—	unknown	—	42.9° 14:40	5.03	52%	78.5°
2042-05-27 Tue	—	unknown	—	42.9° 14:40	4.99	61%	88.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-28&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.