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: 12-16 (89), 12-17 (89), 12-18 (89), 12-19 (89), 12-20 (89) — by astronomy; check the weather when the night is within four days.

2044-12-16astronomy score per night — click a bar for that night2045-01-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-12-16 Fri	89	—	unknown	21:00–03:35 (good, 6.58 h)	42.9° 00:15	11.5	6%	138.9°
2044-12-17 Sat	89	—	unknown	20:55–03:30 (good, 6.58 h)	42.9° 00:10	11.5	2%	144.3°
2044-12-18 Sun	89	—	unknown	20:50–03:25 (good, 6.58 h)	42.9° 00:05	11.51	0%	146.5°
2044-12-19 Mon	89	—	unknown	20:50–03:20 (good, 6.5 h)	42.9° 00:00	11.51	0%	145.1°
2044-12-20 Tue	89	—	unknown	20:45–03:15 (good, 6.5 h)	42.9° 00:00	11.51	2%	140.4°
2044-12-21 Wed	89	—	unknown	20:40–03:15 (good, 6.58 h)	42.9° 23:55	11.51	6%	133.5°
2044-12-22 Thu	89	—	unknown	20:35–03:10 (good, 6.58 h)	42.9° 23:50	11.51	11%	125.3°
2044-12-23 Fri	89	—	unknown	20:35–03:05 (good, 6.5 h)	42.9° 23:45	11.5	17%	116.2°
2044-12-24 Sat	89	—	unknown	20:30–03:00 (good, 6.5 h)	42.9° 23:40	11.5	25%	106.6°
2044-12-25 Sun	89	—	unknown	20:30–03:00 (good, 6.5 h)	42.9° 23:40	11.5	34%	96.6°
2044-12-26 Mon	89	—	unknown	20:35–02:55 (good, 6.33 h)	42.9° 23:35	11.49	44%	86.4°
2044-12-27 Tue	86	—	unknown	20:45–02:50 (good, 6.08 h)	42.9° 23:30	11.49	54%	75.9°
2044-12-28 Wed	81	—	unknown	21:50–02:45 (good, 4.92 h)	42.9° 23:25	11.48	64%	65.4°
2044-12-29 Thu	56	—	unknown	20:00–03:15 (marginal, 7.25 h)	42.9° 23:25	11.47	74%	55.1°
2044-12-30 Fri	36	—	unknown	20:15–03:00 (marginal, 6.75 h)	42.9° 23:20	11.47	83%	45.4°
2044-12-31 Sat	21	—	unknown	22:35–02:30 (marginal, 3.92 h)	42.9° 23:15	11.46	91%	37.6°
2045-01-01 Sun	12	—	unknown	—	42.9° 23:10	11.45	96%	33.6°
2045-01-02 Mon	12	—	unknown	—	42.9° 23:05	11.43	100%	35.2°
2045-01-03 Tue	19	—	unknown	19:55–22:55 (marginal, 3.0 h)	42.9° 23:05	11.42	100%	42.0°
2045-01-04 Wed	34	—	unknown	19:25–01:55 (marginal, 6.5 h)	42.9° 23:00	11.41	96%	51.8°
2045-01-05 Thu	60	—	unknown	19:40–19:50 (good, 0.17 h)	42.9° 22:55	11.4	91%	63.2°
2045-01-06 Fri	85	—	unknown	19:35–00:15 (good, 4.67 h)	42.9° 22:50	11.38	83%	75.1°
2045-01-07 Sat	88	—	unknown	19:35–01:40 (good, 6.08 h)	42.9° 22:45	11.37	73%	86.9°
2045-01-08 Sun	89	—	unknown	19:30–01:45 (good, 6.25 h)	42.9° 22:45	11.35	63%	98.5°
2045-01-09 Mon	89	—	unknown	19:25–01:50 (good, 6.42 h)	42.9° 22:40	11.33	52%	109.5°
2045-01-10 Tue	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.32	42%	119.8°
2045-01-11 Wed	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.3	32%	129.1°
2045-01-12 Thu	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:30	11.28	23%	137.2°
2045-01-13 Fri	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.26	16%	143.2°
2045-01-14 Sat	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.24	9%	146.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-12-16&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.