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: 01-19 (100), 01-20 (100), 01-21 (100), 01-22 (100), 01-23 (100) — by astronomy; check the weather when the night is within four days.

2041-01-13astronomy score per night — click a bar for that night2041-02-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-01-13 Sun	21	—	unknown	22:15–01:25 (marginal, 3.17 h)	72.5° 20:35	11.26	90%	17.4°
2041-01-14 Mon	18	—	unknown	18:55–20:15 (marginal, 1.33 h)	72.5° 20:30	11.24	95%	29.4°
2041-01-15 Tue	27	—	unknown	18:55–22:55 (marginal, 4.0 h)	72.5° 20:30	11.22	98%	41.4°
2041-01-16 Wed	41	—	unknown	18:55–01:10 (marginal, 6.25 h)	72.5° 20:25	11.2	100%	53.3°
2041-01-17 Thu	59	—	unknown	19:00–20:10 (good, 1.17 h)	72.5° 20:20	11.17	100%	65.2°
2041-01-18 Fri	75	—	unknown	19:00–22:40 (good, 3.67 h)	72.5° 20:15	11.15	97%	77.0°
2041-01-19 Sat	100	—	unknown	19:00–00:00 (good, 5.0 h)	72.5° 20:10	11.12	94%	88.8°
2041-01-20 Sun	100	—	unknown	19:00–00:55 (good, 5.92 h)	72.5° 20:10	11.1	88%	100.6°
2041-01-21 Mon	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 20:05	11.07	82%	112.5°
2041-01-22 Tue	100	—	unknown	19:05–01:05 (good, 6.0 h)	72.5° 20:00	11.05	74%	124.5°
2041-01-23 Wed	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 19:55	11.02	65%	136.7°
2041-01-24 Thu	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 19:50	10.99	55%	149.1°
2041-01-25 Fri	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 19:50	10.96	45%	161.8°
2041-01-26 Sat	100	—	unknown	19:10–00:55 (good, 5.75 h)	72.5° 19:45	10.93	34%	174.3°
2041-01-27 Sun	100	—	unknown	19:10–00:50 (good, 5.67 h)	72.5° 19:40	10.9	24%	170.4°
2041-01-28 Mon	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:35	10.87	15%	156.5°
2041-01-29 Tue	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:35	10.84	8%	142.0°
2041-01-30 Wed	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:30	10.81	3%	127.0°
2041-01-31 Thu	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:25	10.78	0%	111.8°
2041-02-01 Fri	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:20	10.75	1%	96.6°
2041-02-02 Sat	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:15	10.71	5%	81.4°
2041-02-03 Sun	100	—	unknown	19:15–00:25 (good, 5.17 h)	72.5° 19:15	10.68	11%	66.5°
2041-02-04 Mon	96	—	unknown	19:20–00:20 (good, 5.0 h)	72.5° 19:10	10.64	19%	52.0°
2041-02-05 Tue	86	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.61	29%	38.0°
2041-02-06 Wed	75	—	unknown	19:20–23:55 (good, 4.58 h)	72.5° 19:00	10.57	39%	24.4°
2041-02-07 Thu	56	—	unknown	19:20–23:35 (good, 4.25 h)	72.5° 18:55	10.54	50%	11.6°
2041-02-08 Fri	40	—	unknown	19:20–00:25 (marginal, 5.08 h)	72.5° 18:55	10.5	60%	3.7°
2041-02-09 Sat	28	—	unknown	19:25–00:10 (marginal, 4.75 h)	72.5° 18:50	10.46	69%	14.5°
2041-02-10 Sun	19	—	unknown	19:25–23:50 (marginal, 4.42 h)	72.5° 18:45	10.43	78%	26.5°
2041-02-11 Mon	19	—	unknown	19:25–23:35 (marginal, 4.17 h)	72.5° 18:40	10.39	85%	38.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-13&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.