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: 01-03 (89), 01-04 (89), 01-05 (89), 01-06 (89), 01-07 (89) — by astronomy; check the weather when the night is within four days.

2031-12-22astronomy score per night — click a bar for that night2032-01-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-12-22 Mon	81	—	unknown	23:00–03:10 (good, 4.17 h)	42.9° 23:55	11.51	70%	63.7°
2031-12-23 Tue	51	—	unknown	20:30–03:40 (marginal, 7.17 h)	42.9° 23:50	11.51	79%	52.6°
2031-12-24 Wed	33	—	unknown	20:50–03:25 (marginal, 6.58 h)	42.9° 23:45	11.5	87%	42.4°
2031-12-25 Thu	19	—	unknown	00:00–02:55 (marginal, 2.92 h)	42.9° 23:40	11.5	93%	33.6°
2031-12-26 Fri	12	—	unknown	—	42.9° 23:35	11.5	97%	27.5°
2031-12-27 Sat	10	—	unknown	—	42.9° 23:35	11.49	99%	25.7°
2031-12-28 Sun	12	—	unknown	—	42.9° 23:30	11.49	100%	29.1°
2031-12-29 Mon	19	—	unknown	20:15–22:50 (marginal, 2.58 h)	42.9° 23:25	11.48	98%	36.0°
2031-12-30 Tue	31	—	unknown	19:50–02:05 (marginal, 6.25 h)	42.9° 23:20	11.47	96%	44.8°
2031-12-31 Wed	49	—	unknown	19:30–02:30 (marginal, 7.0 h)	42.9° 23:15	11.46	91%	54.5°
2032-01-01 Thu	82	—	unknown	20:00–23:00 (good, 3.0 h)	42.9° 23:15	11.45	85%	64.7°
2032-01-02 Fri	86	—	unknown	19:55–01:05 (good, 5.17 h)	42.9° 23:10	11.44	77%	75.2°
2032-01-03 Sat	89	—	unknown	19:50–02:00 (good, 6.17 h)	42.9° 23:05	11.43	69%	86.0°
2032-01-04 Sun	89	—	unknown	19:50–02:05 (good, 6.25 h)	42.9° 23:00	11.42	60%	96.9°
2032-01-05 Mon	89	—	unknown	19:45–02:10 (good, 6.42 h)	42.9° 23:00	11.41	50%	108.1°
2032-01-06 Tue	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:55	11.39	40%	119.3°
2032-01-07 Wed	89	—	unknown	19:35–02:10 (good, 6.58 h)	42.9° 22:50	11.38	30%	130.5°
2032-01-08 Thu	89	—	unknown	19:30–02:05 (good, 6.58 h)	42.9° 22:45	11.36	20%	141.2°
2032-01-09 Fri	89	—	unknown	19:30–02:00 (good, 6.5 h)	42.9° 22:40	11.35	12%	150.0°
2032-01-10 Sat	89	—	unknown	19:25–01:55 (good, 6.5 h)	42.9° 22:40	11.33	5%	154.4°
2032-01-11 Sun	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.31	1%	151.3°
2032-01-12 Mon	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.3	0%	142.3°
2032-01-13 Tue	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.28	2%	130.5°
2032-01-14 Wed	89	—	unknown	19:10–01:40 (good, 6.5 h)	42.9° 22:20	11.26	7%	117.5°
2032-01-15 Thu	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.23	14%	104.4°
2032-01-16 Fri	89	—	unknown	19:05–01:35 (good, 6.5 h)	42.9° 22:15	11.21	23%	91.3°
2032-01-17 Sat	87	—	unknown	19:10–01:30 (good, 6.33 h)	42.9° 22:10	11.19	33%	78.6°
2032-01-18 Sun	83	—	unknown	19:20–01:25 (good, 6.08 h)	42.9° 22:05	11.17	44%	66.5°
2032-01-19 Mon	66	—	unknown	20:35–01:00 (good, 4.42 h)	42.9° 22:05	11.14	55%	55.0°
2032-01-20 Tue	51	—	unknown	19:00–01:50 (marginal, 6.83 h)	42.9° 22:00	11.12	65%	44.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-12-22&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.