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: 01-31 (100), 02-01 (100), 02-02 (100), 02-03 (100), 02-04 (100) — by astronomy; check the weather when the night is within four days.

2040-01-23astronomy score per night — click a bar for that night2040-02-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-23 Mon	31	—	unknown	19:05–01:20 (marginal, 6.25 h)	72.5° 20:00	11.04	76%	7.0°
2040-01-24 Tue	22	—	unknown	19:05–01:00 (marginal, 5.92 h)	72.5° 19:55	11.01	84%	17.4°
2040-01-25 Wed	18	—	unknown	19:05–21:15 (marginal, 2.17 h)	72.5° 19:50	10.98	90%	28.9°
2040-01-26 Thu	23	—	unknown	19:05–23:00 (marginal, 3.92 h)	72.5° 19:45	10.96	95%	40.6°
2040-01-27 Fri	32	—	unknown	19:10–00:30 (marginal, 5.33 h)	72.5° 19:45	10.93	98%	52.4°
2040-01-28 Sat	46	—	unknown	19:10–19:15 (good, 0.08 h)	72.5° 19:40	10.9	100%	64.3°
2040-01-29 Sun	63	—	unknown	19:10–21:45 (good, 2.58 h)	72.5° 19:35	10.87	100%	76.4°
2040-01-30 Mon	80	—	unknown	19:10–23:10 (good, 4.0 h)	72.5° 19:30	10.83	97%	88.7°
2040-01-31 Tue	100	—	unknown	19:15–00:15 (good, 5.0 h)	72.5° 19:30	10.8	93%	101.1°
2040-02-01 Wed	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:25	10.77	88%	113.6°
2040-02-02 Thu	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:20	10.74	80%	126.4°
2040-02-03 Fri	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:15	10.7	71%	139.3°
2040-02-04 Sat	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:10	10.67	61%	152.5°
2040-02-05 Sun	100	—	unknown	19:20–00:20 (good, 5.0 h)	72.5° 19:10	10.64	50%	165.6°
2040-02-06 Mon	100	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.6	39%	174.9°
2040-02-07 Tue	100	—	unknown	19:20–00:10 (good, 4.83 h)	72.5° 19:00	10.56	28%	164.5°
2040-02-08 Wed	100	—	unknown	19:20–00:05 (good, 4.75 h)	72.5° 18:55	10.53	18%	150.4°
2040-02-09 Thu	100	—	unknown	19:25–00:05 (good, 4.67 h)	72.5° 18:50	10.49	10%	135.9°
2040-02-10 Fri	100	—	unknown	19:25–00:00 (good, 4.58 h)	72.5° 18:50	10.45	4%	121.1°
2040-02-11 Sat	100	—	unknown	19:25–23:55 (good, 4.5 h)	72.5° 18:45	10.42	1%	106.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-23&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.