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 Great Orion Nebula: 12-20 (89), 12-21 (89), 12-22 (89), 01-06 (89), 01-07 (89) — by astronomy; check the weather when the night is within four days.

2047-12-20astronomy score per night — click a bar for that night2048-01-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-12-20 Fri	89	—	unknown	20:50–03:20 (good, 6.5 h)	42.9° 00:00	11.51	20%	119.2°
2047-12-21 Sat	89	—	unknown	20:45–03:15 (good, 6.5 h)	42.9° 23:55	11.51	29%	108.0°
2047-12-22 Sun	89	—	unknown	20:50–03:10 (good, 6.33 h)	42.9° 23:55	11.51	39%	97.0°
2047-12-23 Mon	88	—	unknown	20:55–03:10 (good, 6.25 h)	42.9° 23:50	11.51	48%	86.1°
2047-12-24 Tue	85	—	unknown	21:00–03:05 (good, 6.08 h)	42.9° 23:45	11.5	58%	75.6°
2047-12-25 Wed	80	—	unknown	22:30–03:00 (good, 4.5 h)	42.9° 23:40	11.5	68%	65.4°
2047-12-26 Thu	55	—	unknown	20:15–03:30 (marginal, 7.25 h)	42.9° 23:35	11.5	76%	55.7°
2047-12-27 Fri	38	—	unknown	20:30–03:15 (marginal, 6.75 h)	42.9° 23:35	11.49	84%	46.6°
2047-12-28 Sat	24	—	unknown	21:45–02:55 (marginal, 5.17 h)	42.9° 23:30	11.49	90%	38.6°
2047-12-29 Sun	14	—	unknown	01:55–02:15 (marginal, 0.33 h)	42.9° 23:25	11.48	95%	32.6°
2047-12-30 Mon	9	—	unknown	—	42.9° 23:20	11.47	98%	29.9°
2047-12-31 Tue	11	—	unknown	—	42.9° 23:20	11.46	100%	31.4°
2048-01-01 Wed	17	—	unknown	20:10–22:00 (marginal, 1.83 h)	42.9° 23:15	11.45	100%	36.8°
2048-01-02 Thu	28	—	unknown	19:40–01:10 (marginal, 5.5 h)	42.9° 23:10	11.44	97%	44.8°
2048-01-03 Fri	43	—	unknown	19:20–02:15 (marginal, 6.92 h)	42.9° 23:05	11.43	93%	54.3°
2048-01-04 Sat	81	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 23:00	11.42	87%	64.8°
2048-01-05 Sun	86	—	unknown	19:45–00:55 (good, 5.17 h)	42.9° 23:00	11.41	79%	75.9°
2048-01-06 Mon	89	—	unknown	19:40–01:50 (good, 6.17 h)	42.9° 22:55	11.39	70%	87.4°
2048-01-07 Tue	89	—	unknown	19:35–01:55 (good, 6.33 h)	42.9° 22:50	11.38	59%	99.1°
2048-01-08 Wed	89	—	unknown	19:30–02:00 (good, 6.5 h)	42.9° 22:45	11.36	48%	110.9°
2048-01-09 Thu	89	—	unknown	19:30–02:00 (good, 6.5 h)	42.9° 22:40	11.35	37%	122.6°
2048-01-10 Fri	89	—	unknown	19:25–02:00 (good, 6.58 h)	42.9° 22:40	11.33	26%	133.7°
2048-01-11 Sat	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.31	17%	143.2°
2048-01-12 Sun	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.29	9%	149.2°
2048-01-13 Mon	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.27	3%	149.6°
2048-01-14 Tue	89	—	unknown	19:10–01:40 (good, 6.5 h)	42.9° 22:25	11.25	0%	144.0°
2048-01-15 Wed	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.23	0%	134.8°
2048-01-16 Thu	89	—	unknown	19:00–01:35 (good, 6.58 h)	42.9° 22:15	11.21	3%	124.0°
2048-01-17 Fri	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:10	11.19	8%	112.6°
2048-01-18 Sat	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:05	11.16	14%	101.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-12-20&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.