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.

2027-04-19astronomy score per night — click a bar for that night2027-05-18

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-19 Mon	—	unknown	—	72.5° 15:20	7.08	99%	137.5°
2027-04-20 Tue	—	unknown	—	72.5° 15:15	7.02	100%	150.9°
2027-04-21 Wed	—	unknown	—	72.5° 15:10	6.96	99%	164.0°
2027-04-22 Thu	—	unknown	—	72.5° 15:10	6.9	96%	176.8°
2027-04-23 Fri	—	unknown	—	72.5° 15:05	6.84	90%	170.5°
2027-04-24 Sat	—	unknown	—	72.5° 15:00	6.78	84%	158.2°
2027-04-25 Sun	—	unknown	—	72.5° 14:55	6.73	76%	146.1°
2027-04-26 Mon	—	unknown	—	72.5° 14:50	6.67	68%	134.1°
2027-04-27 Tue	—	unknown	—	72.5° 14:50	6.61	59%	122.3°
2027-04-28 Wed	—	unknown	—	72.5° 14:45	6.55	49%	110.4°
2027-04-29 Thu	—	unknown	—	72.5° 14:40	6.49	40%	98.5°
2027-04-30 Fri	—	unknown	—	72.5° 14:35	6.43	31%	86.4°
2027-05-01 Sat	—	unknown	—	72.5° 14:30	6.38	22%	74.1°
2027-05-02 Sun	—	unknown	—	72.5° 14:30	6.32	14%	61.5°
2027-05-03 Mon	—	unknown	—	72.5° 14:25	6.26	8%	48.5°
2027-05-04 Tue	—	unknown	—	72.5° 14:20	6.2	3%	35.1°
2027-05-05 Wed	—	unknown	—	72.5° 14:15	6.15	0%	21.4°
2027-05-06 Thu	—	unknown	—	72.5° 14:15	6.09	0%	7.4°
2027-05-07 Fri	—	unknown	—	72.5° 14:10	6.03	3%	6.9°
2027-05-08 Sat	—	unknown	—	72.5° 14:05	5.98	8%	21.3°
2027-05-09 Sun	—	unknown	—	72.5° 14:00	5.92	16%	35.8°
2027-05-10 Mon	—	unknown	—	72.5° 13:55	5.86	25%	50.2°
2027-05-11 Tue	—	unknown	—	72.5° 13:55	5.81	36%	64.5°
2027-05-12 Wed	—	unknown	—	72.5° 13:50	5.75	47%	78.7°
2027-05-13 Thu	—	unknown	—	72.5° 13:45	5.7	58%	92.8°
2027-05-14 Fri	—	unknown	—	72.5° 13:40	5.64	69%	106.6°
2027-05-15 Sat	—	unknown	—	72.5° 13:35	5.59	79%	120.2°
2027-05-16 Sun	—	unknown	—	72.5° 13:35	5.54	87%	133.7°
2027-05-17 Mon	—	unknown	—	72.5° 13:30	5.48	93%	146.9°
2027-05-18 Tue	—	unknown	—	72.5° 13:25	5.43	97%	159.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-19&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.