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.

Best nights for Seven Sisters: 02-12 (100), 02-13 (100), 02-14 (100), 02-15 (95), 02-16 (87) — by astronomy; check the weather when the night is within four days.

2040-02-12astronomy score per night — click a bar for that night2040-03-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-02-12 Sun	100	—	unknown	19:25–23:50 (good, 4.42 h)	72.5° 18:40	10.38	0%	91.6°
2040-02-13 Mon	100	—	unknown	19:25–23:45 (good, 4.33 h)	72.5° 18:35	10.34	3%	77.2°
2040-02-14 Tue	100	—	unknown	19:30–23:45 (good, 4.25 h)	72.5° 18:35	10.3	7%	63.2°
2040-02-15 Wed	95	—	unknown	19:30–23:40 (good, 4.17 h)	72.5° 18:30	10.26	14%	49.6°
2040-02-16 Thu	87	—	unknown	19:30–23:35 (good, 4.08 h)	72.5° 18:25	10.22	22%	36.5°
2040-02-17 Fri	71	—	unknown	19:30–23:20 (good, 3.83 h)	72.5° 18:20	10.18	31%	23.9°
2040-02-18 Sat	55	—	unknown	19:35–23:05 (good, 3.5 h)	72.5° 18:15	10.14	41%	12.0°
2040-02-19 Sun	42	—	unknown	19:35–21:30 (good, 1.92 h)	72.5° 18:15	10.1	50%	5.1°
2040-02-20 Mon	30	—	unknown	19:35–23:40 (marginal, 4.08 h)	72.5° 18:10	10.06	60%	14.0°
2040-02-21 Tue	22	—	unknown	19:35–23:20 (marginal, 3.75 h)	72.5° 18:05	10.02	69%	25.4°
2040-02-22 Wed	18	—	unknown	19:35–23:05 (marginal, 3.5 h)	72.5° 18:00	9.97	77%	37.1°
2040-02-23 Thu	20	—	unknown	19:40–23:00 (marginal, 3.33 h)	72.5° 17:55	9.93	84%	48.9°
2040-02-24 Fri	23	—	unknown	19:40–23:00 (marginal, 3.33 h)	72.5° 17:55	9.89	91%	60.8°
2040-02-25 Sat	30	—	unknown	19:10–23:05 (marginal, 3.92 h)	72.5° 17:50	9.84	96%	72.8°
2040-02-26 Sun	39	—	unknown	19:40–20:55 (good, 1.25 h)	72.5° 17:45	9.8	99%	85.1°
2040-02-27 Mon	48	—	unknown	19:45–22:05 (good, 2.33 h)	72.5° 17:40	9.75	100%	97.6°
2040-02-28 Tue	58	—	unknown	19:45–22:30 (good, 2.75 h)	72.5° 17:40	9.71	99%	110.3°
2040-02-29 Wed	71	—	unknown	19:45–22:35 (good, 2.83 h)	72.5° 17:35	9.66	96%	123.2°
2040-03-01 Thu	72	—	unknown	19:45–22:30 (good, 2.75 h)	72.5° 17:30	9.62	91%	136.3°
2040-03-02 Fri	71	—	unknown	19:50–22:30 (good, 2.67 h)	72.5° 17:25	9.57	84%	149.5°
2040-03-03 Sat	70	—	unknown	19:50–22:35 (good, 2.75 h)	72.5° 17:20	9.53	75%	162.8°
2040-03-04 Sun	67	—	unknown	19:50–22:30 (good, 2.67 h)	72.5° 17:20	9.48	65%	174.4°
2040-03-05 Mon	65	—	unknown	19:50–22:25 (good, 2.58 h)	72.5° 17:15	9.43	54%	168.0°
2040-03-06 Tue	62	—	unknown	19:55–22:20 (good, 2.42 h)	72.5° 17:10	9.39	43%	154.4°
2040-03-07 Wed	60	—	unknown	19:55–22:15 (good, 2.33 h)	72.5° 17:05	9.34	32%	140.4°
2040-03-08 Thu	58	—	unknown	19:55–22:15 (good, 2.33 h)	72.5° 17:00	9.29	22%	126.1°
2040-03-09 Fri	56	—	unknown	19:55–22:10 (good, 2.25 h)	72.5° 17:00	9.24	13%	111.8°
2040-03-10 Sat	54	—	unknown	19:55–22:05 (good, 2.17 h)	72.5° 16:55	9.19	6%	97.4°
2040-03-11 Sun	51	—	unknown	20:00–22:00 (good, 2.0 h)	72.5° 16:50	9.15	2%	83.2°
2040-03-12 Mon	50	—	unknown	20:00–21:55 (good, 1.92 h)	72.5° 16:45	9.1	0%	69.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-02-12&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.