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.

2042-07-15astronomy score per night — click a bar for that night2042-08-13

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-07-15 Tue	—	unknown	—	42.9° 11:20	5.0	2%	36.2°
2042-07-16 Wed	—	unknown	—	42.9° 11:15	5.05	0%	43.0°
2042-07-17 Thu	—	unknown	—	42.9° 11:15	5.09	1%	51.7°
2042-07-18 Fri	—	unknown	—	42.9° 11:10	5.14	3%	61.4°
2042-07-19 Sat	—	unknown	—	42.9° 11:05	5.18	8%	71.4°
2042-07-20 Sun	—	unknown	—	42.9° 11:00	5.23	14%	81.6°
2042-07-21 Mon	—	unknown	—	42.9° 11:00	5.28	21%	91.7°
2042-07-22 Tue	—	unknown	—	42.9° 10:55	5.33	29%	101.7°
2042-07-23 Wed	—	unknown	—	42.9° 10:50	5.38	38%	111.4°
2042-07-24 Thu	—	unknown	—	42.9° 10:45	5.43	47%	120.8°
2042-07-25 Fri	—	unknown	—	42.9° 10:40	5.48	57%	129.7°
2042-07-26 Sat	—	unknown	—	42.9° 10:40	5.53	66%	137.6°
2042-07-27 Sun	—	unknown	—	42.9° 10:35	5.58	75%	143.7°
2042-07-28 Mon	—	unknown	—	42.9° 10:30	5.64	84%	146.8°
2042-07-29 Tue	—	unknown	—	42.9° 10:25	5.69	90%	145.7°
2042-07-30 Wed	—	unknown	—	42.9° 10:20	5.74	96%	140.4°
2042-07-31 Thu	—	unknown	—	42.9° 10:20	5.8	99%	132.1°
2042-08-01 Fri	—	unknown	—	42.9° 10:15	5.85	100%	121.9°
2042-08-02 Sat	—	unknown	—	42.9° 10:10	5.91	98%	110.6°
2042-08-03 Sun	—	unknown	—	42.9° 10:05	5.97	93%	98.6°
2042-08-04 Mon	—	unknown	—	42.9° 10:05	6.02	86%	86.4°
2042-08-05 Tue	—	unknown	—	42.9° 10:00	6.08	77%	74.4°
2042-08-06 Wed	—	unknown	—	42.9° 09:55	6.13	67%	62.7°
2042-08-07 Thu	—	unknown	—	42.9° 09:50	6.19	56%	51.9°
2042-08-08 Fri	—	unknown	—	42.9° 09:45	6.25	44%	42.7°
2042-08-09 Sat	—	unknown	—	42.9° 09:45	6.3	34%	36.0°
2042-08-10 Sun	—	unknown	—	42.9° 09:40	6.36	24%	33.2°
2042-08-11 Mon	—	unknown	—	42.9° 09:35	6.42	15%	35.1°
2042-08-12 Tue	—	unknown	—	42.9° 09:30	6.48	8%	40.9°
2042-08-13 Wed	—	unknown	—	42.9° 09:25	6.53	4%	49.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-07-15&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.