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: 11-28 (100), 11-29 (100), 11-30 (100), 12-01 (100), 12-02 (100) — by astronomy; check the weather when the night is within four days.

2027-11-28astronomy score per night — click a bar for that night2027-12-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-11-28 Sun	100	—	unknown	18:35–04:50 (good, 10.25 h)	72.5° 23:40	11.27	1%	164.1°
2027-11-29 Mon	100	—	unknown	18:35–04:45 (good, 10.17 h)	72.5° 23:35	11.29	3%	151.4°
2027-11-30 Tue	100	—	unknown	18:35–04:40 (good, 10.08 h)	72.5° 23:30	11.31	8%	139.0°
2027-12-01 Wed	100	—	unknown	18:35–04:40 (good, 10.08 h)	72.5° 23:25	11.33	14%	126.9°
2027-12-02 Thu	100	—	unknown	18:35–04:35 (good, 10.0 h)	72.5° 23:25	11.34	21%	114.9°
2027-12-03 Fri	100	—	unknown	18:35–04:30 (good, 9.92 h)	72.5° 23:20	11.36	29%	103.0°
2027-12-04 Sat	100	—	unknown	18:35–04:25 (good, 9.83 h)	72.5° 23:15	11.38	38%	91.2°
2027-12-05 Sun	100	—	unknown	18:35–04:20 (good, 9.75 h)	72.5° 23:10	11.39	47%	79.3°
2027-12-06 Mon	100	—	unknown	18:40–04:20 (good, 9.67 h)	72.5° 23:05	11.4	57%	67.3°
2027-12-07 Tue	95	—	unknown	20:20–04:15 (good, 7.92 h)	72.5° 23:05	11.42	66%	55.2°
2027-12-08 Wed	86	—	unknown	00:00–04:10 (good, 4.17 h)	72.5° 23:00	11.43	75%	42.7°
2027-12-09 Thu	63	—	unknown	04:00–04:05 (good, 0.08 h)	72.5° 22:55	11.44	83%	29.9°
2027-12-10 Fri	38	—	unknown	18:35–04:15 (marginal, 9.67 h)	72.5° 22:50	11.45	90%	16.7°
2027-12-11 Sat	26	—	unknown	01:05–03:50 (marginal, 2.75 h)	72.5° 22:50	11.46	96%	3.1°
2027-12-12 Sun	22	—	unknown	18:35–20:10 (marginal, 1.58 h)	72.5° 22:45	11.47	99%	10.9°
2027-12-13 Mon	26	—	unknown	18:35–21:20 (marginal, 2.75 h)	72.5° 22:40	11.48	100%	25.3°
2027-12-14 Tue	45	—	unknown	18:35–00:50 (marginal, 6.25 h)	72.5° 22:35	11.48	98%	39.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-11-28&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.