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: 12-20 (100), 12-21 (100), 12-22 (100), 12-23 (100), 12-24 (100) — by astronomy; check the weather when the night is within four days.

2030-12-20astronomy score per night — click a bar for that night2031-01-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-12-20 Fri	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:10	11.51	20%	156.4°
2030-12-21 Sat	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:10	11.51	11%	170.6°
2030-12-22 Sun	100	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:05	11.51	5%	172.9°
2030-12-23 Mon	100	—	unknown	18:40–03:10 (good, 8.5 h)	72.5° 22:00	11.51	1%	158.4°
2030-12-24 Tue	100	—	unknown	18:40–03:05 (good, 8.42 h)	72.5° 21:55	11.5	0%	143.2°
2030-12-25 Wed	100	—	unknown	18:40–03:05 (good, 8.42 h)	72.5° 21:50	11.5	2%	128.0°
2030-12-26 Thu	100	—	unknown	18:40–03:00 (good, 8.33 h)	72.5° 21:50	11.5	7%	113.1°
2030-12-27 Fri	100	—	unknown	18:40–02:55 (good, 8.25 h)	72.5° 21:45	11.49	14%	98.6°
2030-12-28 Sat	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:40	11.48	23%	84.5°
2030-12-29 Sun	100	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 21:35	11.48	33%	70.9°
2030-12-30 Mon	97	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 21:30	11.47	44%	57.8°
2030-12-31 Tue	89	—	unknown	18:45–02:40 (good, 7.92 h)	72.5° 21:30	11.46	54%	45.1°
2031-01-01 Wed	81	—	unknown	22:30–02:35 (good, 4.08 h)	72.5° 21:25	11.45	64%	32.7°
2031-01-02 Thu	53	—	unknown	18:45–02:55 (marginal, 8.17 h)	72.5° 21:20	11.44	72%	20.7°
2031-01-03 Fri	39	—	unknown	18:45–02:40 (marginal, 7.92 h)	72.5° 21:15	11.43	81%	9.1°
2031-01-04 Sat	27	—	unknown	18:45–02:25 (marginal, 7.67 h)	72.5° 21:15	11.42	88%	4.9°
2031-01-05 Sun	22	—	unknown	18:45–20:35 (marginal, 1.83 h)	72.5° 21:10	11.4	93%	15.7°
2031-01-06 Mon	21	—	unknown	18:50–20:35 (marginal, 1.75 h)	72.5° 21:05	11.39	97%	27.4°
2031-01-07 Tue	31	—	unknown	18:50–23:05 (marginal, 4.25 h)	72.5° 21:00	11.38	99%	39.2°
2031-01-08 Wed	48	—	unknown	18:50–01:45 (marginal, 6.92 h)	72.5° 20:55	11.36	100%	51.1°
2031-01-09 Thu	69	—	unknown	18:50–20:40 (good, 1.83 h)	72.5° 20:55	11.34	99%	63.1°
2031-01-10 Fri	100	—	unknown	18:50–23:15 (good, 4.42 h)	72.5° 20:50	11.33	96%	75.2°
2031-01-11 Sat	100	—	unknown	18:50–00:40 (good, 5.83 h)	72.5° 20:45	11.31	91%	87.4°
2031-01-12 Sun	100	—	unknown	18:55–01:30 (good, 6.58 h)	72.5° 20:40	11.29	84%	99.9°
2031-01-13 Mon	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:35	11.27	76%	112.5°
2031-01-14 Tue	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:35	11.25	67%	125.4°
2031-01-15 Wed	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:30	11.23	56%	138.5°
2031-01-16 Thu	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:25	11.21	46%	151.9°
2031-01-17 Fri	100	—	unknown	19:00–01:30 (good, 6.5 h)	72.5° 20:20	11.19	35%	165.6°
2031-01-18 Sat	100	—	unknown	19:00–01:30 (good, 6.5 h)	72.5° 20:15	11.16	24%	176.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-12-20&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.