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: 12-16 (100), 12-17 (100), 12-18 (100), 12-19 (100), 12-20 (100) — by astronomy; check the weather when the night is within four days.

2039-12-16astronomy score per night — click a bar for that night2040-01-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-12-16 Fri	100	—	unknown	18:35–03:40 (good, 9.08 h)	72.5° 22:30	11.5	2%	137.4°
2039-12-17 Sat	100	—	unknown	18:35–03:35 (good, 9.0 h)	72.5° 22:25	11.5	8%	122.4°
2039-12-18 Sun	100	—	unknown	18:35–03:30 (good, 8.92 h)	72.5° 22:20	11.5	15%	107.8°
2039-12-19 Mon	100	—	unknown	18:35–03:30 (good, 8.92 h)	72.5° 22:15	11.51	24%	93.5°
2039-12-20 Tue	100	—	unknown	18:35–03:25 (good, 8.83 h)	72.5° 22:15	11.51	34%	79.7°
2039-12-21 Wed	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:10	11.51	45%	66.3°
2039-12-22 Thu	96	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:05	11.51	55%	53.4°
2039-12-23 Fri	87	—	unknown	21:10–03:10 (good, 6.0 h)	72.5° 22:00	11.51	65%	40.9°
2039-12-24 Sat	71	—	unknown	02:50–03:10 (good, 0.33 h)	72.5° 21:55	11.5	74%	28.7°
2039-12-25 Sun	46	—	unknown	18:40–03:20 (marginal, 8.67 h)	72.5° 21:55	11.5	82%	16.9°
2039-12-26 Mon	32	—	unknown	18:40–03:05 (marginal, 8.42 h)	72.5° 21:50	11.5	89%	6.7°
2039-12-27 Tue	24	—	unknown	18:40–20:30 (marginal, 1.83 h)	72.5° 21:45	11.49	94%	9.4°
2039-12-28 Wed	22	—	unknown	18:40–20:25 (marginal, 1.75 h)	72.5° 21:40	11.49	98%	20.4°
2039-12-29 Thu	25	—	unknown	18:40–21:05 (marginal, 2.42 h)	72.5° 21:35	11.48	100%	31.9°
2039-12-30 Fri	40	—	unknown	18:40–00:15 (marginal, 5.58 h)	72.5° 21:35	11.47	100%	43.7°
2039-12-31 Sat	61	—	unknown	18:45–19:45 (good, 1.0 h)	72.5° 21:30	11.46	98%	55.5°
2040-01-01 Sun	95	—	unknown	18:45–22:15 (good, 3.5 h)	72.5° 21:25	11.45	95%	67.4°
2040-01-02 Mon	100	—	unknown	18:45–00:25 (good, 5.67 h)	72.5° 21:20	11.44	90%	79.4°
2040-01-03 Tue	100	—	unknown	18:45–01:45 (good, 7.0 h)	72.5° 21:20	11.43	83%	91.5°
2040-01-04 Wed	100	—	unknown	18:45–02:10 (good, 7.42 h)	72.5° 21:15	11.42	75%	103.9°
2040-01-05 Thu	100	—	unknown	18:45–02:10 (good, 7.42 h)	72.5° 21:10	11.41	66%	116.5°
2040-01-06 Fri	100	—	unknown	18:45–02:10 (good, 7.42 h)	72.5° 21:05	11.39	56%	129.3°
2040-01-07 Sat	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.38	45%	142.5°
2040-01-08 Sun	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.36	34%	155.9°
2040-01-09 Mon	100	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.35	24%	169.2°
2040-01-10 Tue	100	—	unknown	18:50–02:00 (good, 7.17 h)	72.5° 20:50	11.33	15%	172.7°
2040-01-11 Wed	100	—	unknown	18:50–01:55 (good, 7.08 h)	72.5° 20:45	11.31	7%	159.3°
2040-01-12 Thu	100	—	unknown	18:55–01:55 (good, 7.0 h)	72.5° 20:40	11.29	2%	144.5°
2040-01-13 Fri	100	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:40	11.27	0%	129.4°
2040-01-14 Sat	100	—	unknown	18:55–01:45 (good, 6.83 h)	72.5° 20:35	11.25	1%	114.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-12-16&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.