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.

2047-04-19astronomy score per night — click a bar for that night2047-05-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-04-19 Fri	—	unknown	—	42.9° 17:10	7.07	23%	110.0°
2047-04-20 Sat	—	unknown	—	42.9° 17:05	7.01	16%	99.7°
2047-04-21 Sun	—	unknown	—	42.9° 17:00	6.95	10%	89.5°
2047-04-22 Mon	—	unknown	—	42.9° 16:55	6.89	5%	79.3°
2047-04-23 Tue	—	unknown	—	42.9° 16:50	6.83	2%	69.3°
2047-04-24 Wed	—	unknown	—	42.9° 16:50	6.78	0%	59.6°
2047-04-25 Thu	—	unknown	—	42.9° 16:45	6.72	1%	50.3°
2047-04-26 Fri	—	unknown	—	42.9° 16:40	6.66	3%	42.0°
2047-04-27 Sat	—	unknown	—	42.9° 16:35	6.6	7%	35.3°
2047-04-28 Sun	—	unknown	—	42.9° 16:35	6.54	12%	31.3°
2047-04-29 Mon	—	unknown	—	42.9° 16:30	6.48	19%	31.3°
2047-04-30 Tue	—	unknown	—	42.9° 16:25	6.43	28%	35.4°
2047-05-01 Wed	—	unknown	—	42.9° 16:20	6.37	37%	42.7°
2047-05-02 Thu	—	unknown	—	42.9° 16:15	6.31	48%	52.0°
2047-05-03 Fri	—	unknown	—	42.9° 16:15	6.25	58%	62.6°
2047-05-04 Sat	—	unknown	—	42.9° 16:10	6.19	69%	74.2°
2047-05-05 Sun	—	unknown	—	42.9° 16:05	6.14	79%	86.4°
2047-05-06 Mon	—	unknown	—	42.9° 16:00	6.08	88%	99.0°
2047-05-07 Tue	—	unknown	—	42.9° 15:55	6.02	95%	111.7°
2047-05-08 Wed	—	unknown	—	42.9° 15:55	5.97	99%	124.0°
2047-05-09 Thu	—	unknown	—	42.9° 15:50	5.91	100%	135.3°
2047-05-10 Fri	—	unknown	—	42.9° 15:45	5.85	98%	144.3°
2047-05-11 Sat	—	unknown	—	42.9° 15:40	5.8	93%	149.1°
2047-05-12 Sun	—	unknown	—	42.9° 15:40	5.74	86%	147.9°
2047-05-13 Mon	—	unknown	—	42.9° 15:35	5.69	78%	141.8°
2047-05-14 Tue	—	unknown	—	42.9° 15:30	5.64	68%	133.1°
2047-05-15 Wed	—	unknown	—	42.9° 15:25	5.58	58%	123.2°
2047-05-16 Thu	—	unknown	—	42.9° 15:20	5.53	48%	112.9°
2047-05-17 Fri	—	unknown	—	42.9° 15:20	5.48	38%	102.6°
2047-05-18 Sat	—	unknown	—	42.9° 15:15	5.42	29%	92.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-04-19&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.