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: 03-01 (72), 02-29 (71), 03-02 (71), 03-03 (70), 03-04 (67) — by astronomy; check the weather when the night is within four days.

2040-02-23astronomy score per night — click a bar for that night2040-03-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2040-03-13 Tue	47	—	unknown	20:00–21:55 (good, 1.92 h)	72.5° 16:40	9.05	1%	55.3°
2040-03-14 Wed	45	—	unknown	20:00–21:50 (good, 1.83 h)	72.5° 16:40	9.0	4%	41.9°
2040-03-15 Thu	40	—	unknown	20:05–21:45 (good, 1.67 h)	72.5° 16:35	8.95	10%	28.8°
2040-03-16 Fri	34	—	unknown	20:05–21:35 (good, 1.5 h)	72.5° 16:30	8.9	16%	16.3°
2040-03-17 Sat	28	—	unknown	20:05–21:25 (good, 1.33 h)	72.5° 16:25	8.84	24%	5.7°
2040-03-18 Sun	23	—	unknown	20:05–21:15 (good, 1.17 h)	72.5° 16:25	8.79	33%	10.1°
2040-03-19 Mon	17	—	unknown	19:35–21:55 (marginal, 2.33 h)	72.5° 16:20	8.74	42%	21.5°
2040-03-20 Tue	13	—	unknown	20:10–21:45 (marginal, 1.58 h)	72.5° 16:15	8.69	52%	33.2°
2040-03-21 Wed	11	—	unknown	20:10–21:35 (marginal, 1.42 h)	72.5° 16:10	8.64	61%	44.9°
2040-03-22 Thu	10	—	unknown	20:10–21:30 (marginal, 1.33 h)	72.5° 16:05	8.59	70%	56.7°
2040-03-23 Fri	10	—	unknown	20:15–21:30 (marginal, 1.25 h)	72.5° 16:05	8.53	78%	68.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-02-23&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.