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.

2043-04-21astronomy score per night — click a bar for that night2043-05-20

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-04-21 Tue	—	unknown	—	79.2° 13:00	6.95	95%	146.6°
2043-04-22 Wed	—	unknown	—	79.2° 12:55	6.89	98%	156.0°
2043-04-23 Thu	—	unknown	—	79.2° 12:50	6.84	100%	162.1°
2043-04-24 Fri	—	unknown	—	79.2° 12:50	6.78	100%	161.7°
2043-04-25 Sat	—	unknown	—	79.2° 12:45	6.72	98%	155.0°
2043-04-26 Sun	—	unknown	—	79.2° 12:40	6.66	94%	145.5°
2043-04-27 Mon	—	unknown	—	79.2° 12:35	6.6	88%	135.0°
2043-04-28 Tue	—	unknown	—	79.2° 12:30	6.54	82%	123.9°
2043-04-29 Wed	—	unknown	—	79.2° 12:30	6.49	74%	112.5°
2043-04-30 Thu	—	unknown	—	79.2° 12:25	6.43	64%	100.8°
2043-05-01 Fri	—	unknown	—	79.2° 12:20	6.37	55%	88.8°
2043-05-02 Sat	—	unknown	—	79.2° 12:15	6.31	44%	76.5°
2043-05-03 Sun	—	unknown	—	79.2° 12:15	6.25	34%	63.8°
2043-05-04 Mon	—	unknown	—	79.2° 12:10	6.2	24%	50.9°
2043-05-05 Tue	—	unknown	—	79.2° 12:05	6.14	15%	37.9°
2043-05-06 Wed	—	unknown	—	79.2° 12:00	6.08	7%	25.9°
2043-05-07 Thu	—	unknown	—	79.2° 11:55	6.03	2%	17.7°
2043-05-08 Fri	—	unknown	—	79.2° 11:50	5.97	0%	20.0°
2043-05-09 Sat	—	unknown	—	79.2° 11:45	5.91	1%	30.6°
2043-05-10 Sun	—	unknown	—	79.2° 11:40	5.86	5%	43.8°
2043-05-11 Mon	—	unknown	—	79.2° 11:35	5.8	12%	57.4°
2043-05-12 Tue	—	unknown	—	79.2° 11:35	5.75	20%	71.1°
2043-05-13 Wed	—	unknown	—	79.2° 11:30	5.69	30%	84.4°
2043-05-14 Thu	—	unknown	—	79.2° 11:25	5.64	40%	97.3°
2043-05-15 Fri	—	unknown	—	79.2° 11:20	5.58	50%	109.7°
2043-05-16 Sat	—	unknown	—	79.2° 11:20	5.53	61%	121.7°
2043-05-17 Sun	—	unknown	—	79.2° 11:15	5.48	70%	133.3°
2043-05-18 Mon	—	unknown	—	79.2° 11:10	5.43	79%	144.1°
2043-05-19 Tue	—	unknown	—	79.2° 11:05	5.38	86%	153.9°
2043-05-20 Wed	—	unknown	—	79.2° 11:00	5.33	92%	161.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-04-21&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.