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: 12-17 (100), 12-18 (100), 12-19 (100), 12-20 (100), 12-21 (100) — by astronomy; check the weather when the night is within four days.

2027-12-15astronomy score per night — click a bar for that night2028-01-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-15 Wed	87	—	unknown	18:35–21:10 (good, 2.58 h)	72.5° 22:30	11.49	93%	54.5°
2027-12-16 Thu	98	—	unknown	18:35–00:45 (good, 6.17 h)	72.5° 22:30	11.5	86%	69.2°
2027-12-17 Fri	100	—	unknown	18:35–02:35 (good, 8.0 h)	72.5° 22:25	11.5	77%	83.8°
2027-12-18 Sat	100	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:20	11.5	66%	98.2°
2027-12-19 Sun	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:15	11.51	55%	112.3°
2027-12-20 Mon	100	—	unknown	18:35–03:20 (good, 8.75 h)	72.5° 22:10	11.51	44%	126.2°
2027-12-21 Tue	100	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:10	11.51	33%	139.9°
2027-12-22 Wed	100	—	unknown	18:35–03:15 (good, 8.67 h)	72.5° 22:05	11.51	24%	153.3°
2027-12-23 Thu	100	—	unknown	18:40–03:10 (good, 8.5 h)	72.5° 22:00	11.51	15%	166.4°
2027-12-24 Fri	100	—	unknown	18:40–03:05 (good, 8.42 h)	72.5° 21:55	11.5	8%	179.2°
2027-12-25 Sat	100	—	unknown	18:40–03:05 (good, 8.42 h)	72.5° 21:55	11.5	4%	167.8°
2027-12-26 Sun	100	—	unknown	18:40–03:00 (good, 8.33 h)	72.5° 21:50	11.5	1%	155.2°
2027-12-27 Mon	100	—	unknown	18:40–02:55 (good, 8.25 h)	72.5° 21:45	11.49	0%	142.8°
2027-12-28 Tue	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:40	11.49	1%	130.6°
2027-12-29 Wed	100	—	unknown	18:40–02:50 (good, 8.17 h)	72.5° 21:35	11.48	4%	118.6°
2027-12-30 Thu	100	—	unknown	18:40–02:45 (good, 8.08 h)	72.5° 21:35	11.47	9%	106.6°
2027-12-31 Fri	100	—	unknown	18:45–02:40 (good, 7.92 h)	72.5° 21:30	11.46	15%	94.8°
2028-01-01 Sat	100	—	unknown	18:45–02:35 (good, 7.83 h)	72.5° 21:25	11.45	22%	82.9°
2028-01-02 Sun	100	—	unknown	18:45–02:30 (good, 7.75 h)	72.5° 21:20	11.44	30%	71.1°
2028-01-03 Mon	98	—	unknown	18:45–02:30 (good, 7.75 h)	72.5° 21:15	11.43	39%	59.2°
2028-01-04 Tue	90	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:15	11.42	49%	47.1°
2028-01-05 Wed	81	—	unknown	20:40–02:20 (good, 5.67 h)	72.5° 21:10	11.41	58%	34.7°
2028-01-06 Thu	56	—	unknown	18:45–02:40 (marginal, 7.92 h)	72.5° 21:05	11.4	68%	22.0°
2028-01-07 Fri	40	—	unknown	18:50–02:25 (marginal, 7.58 h)	72.5° 21:00	11.38	78%	8.8°
2028-01-08 Sat	26	—	unknown	18:50–02:05 (marginal, 7.25 h)	72.5° 21:00	11.37	86%	4.8°
2028-01-09 Sun	20	—	unknown	18:50–20:15 (marginal, 1.42 h)	72.5° 20:55	11.35	93%	18.9°
2028-01-10 Mon	22	—	unknown	18:50–20:55 (marginal, 2.08 h)	72.5° 20:50	11.33	98%	33.4°
2028-01-11 Tue	39	—	unknown	18:50–00:40 (marginal, 5.83 h)	72.5° 20:45	11.31	100%	48.2°
2028-01-12 Wed	65	—	unknown	18:55–20:20 (good, 1.42 h)	72.5° 20:40	11.3	99%	63.3°
2028-01-13 Thu	100	—	unknown	18:55–23:20 (good, 4.42 h)	72.5° 20:40	11.28	95%	78.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-15&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.