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: 12-28 (89), 12-29 (89), 12-30 (89), 12-31 (89), 01-01 (89) — by astronomy; check the weather when the night is within four days.

2037-12-21astronomy score per night — click a bar for that night2038-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-12-21 Mon	10	—	unknown	—	42.9° 23:55	11.51	100%	26.3°
2037-12-22 Tue	10	—	unknown	—	42.9° 23:50	11.51	100%	30.0°
2037-12-23 Wed	19	—	unknown	20:40–23:15 (marginal, 2.58 h)	42.9° 23:45	11.5	98%	38.1°
2037-12-24 Thu	33	—	unknown	20:10–02:35 (marginal, 6.42 h)	42.9° 23:45	11.5	94%	48.5°
2037-12-25 Fri	51	—	unknown	19:55–03:00 (marginal, 7.08 h)	42.9° 23:40	11.5	87%	60.1°
2037-12-26 Sat	82	—	unknown	20:20–00:45 (good, 4.42 h)	42.9° 23:35	11.49	78%	72.3°
2037-12-27 Sun	87	—	unknown	20:15–02:20 (good, 6.08 h)	42.9° 23:30	11.49	68%	84.9°
2037-12-28 Mon	89	—	unknown	20:15–02:30 (good, 6.25 h)	42.9° 23:25	11.48	57%	97.5°
2037-12-29 Tue	89	—	unknown	20:10–02:35 (good, 6.42 h)	42.9° 23:25	11.48	46%	110.1°
2037-12-30 Wed	89	—	unknown	20:05–02:35 (good, 6.5 h)	42.9° 23:20	11.47	35%	122.4°
2037-12-31 Thu	89	—	unknown	20:00–02:35 (good, 6.58 h)	42.9° 23:15	11.46	24%	134.0°
2038-01-01 Fri	89	—	unknown	20:00–02:30 (good, 6.5 h)	42.9° 23:10	11.45	15%	144.3°
2038-01-02 Sat	89	—	unknown	19:55–02:25 (good, 6.5 h)	42.9° 23:10	11.44	8%	151.6°
2038-01-03 Sun	89	—	unknown	19:50–02:25 (good, 6.58 h)	42.9° 23:05	11.43	3%	153.7°
2038-01-04 Mon	89	—	unknown	19:45–02:20 (good, 6.58 h)	42.9° 23:00	11.41	0%	149.5°
2038-01-05 Tue	89	—	unknown	19:40–02:15 (good, 6.58 h)	42.9° 22:55	11.4	0%	141.3°
2038-01-06 Wed	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:50	11.39	2%	131.3°
2038-01-07 Thu	89	—	unknown	19:35–02:05 (good, 6.5 h)	42.9° 22:50	11.37	6%	120.6°
2038-01-08 Fri	89	—	unknown	19:30–02:05 (good, 6.58 h)	42.9° 22:45	11.36	12%	109.7°
2038-01-09 Sat	89	—	unknown	19:30–02:00 (good, 6.5 h)	42.9° 22:40	11.34	18%	98.8°
2038-01-10 Sun	89	—	unknown	19:30–01:55 (good, 6.42 h)	42.9° 22:35	11.32	26%	88.0°
2038-01-11 Mon	88	—	unknown	19:30–01:50 (good, 6.33 h)	42.9° 22:30	11.3	35%	77.4°
2038-01-12 Tue	86	—	unknown	19:40–01:50 (good, 6.17 h)	42.9° 22:30	11.28	44%	66.9°
2038-01-13 Wed	81	—	unknown	20:25–01:45 (good, 5.33 h)	42.9° 22:25	11.27	54%	56.7°
2038-01-14 Thu	59	—	unknown	23:35–01:05 (good, 1.5 h)	42.9° 22:20	11.24	63%	46.8°
2038-01-15 Fri	41	—	unknown	19:00–02:00 (marginal, 7.0 h)	42.9° 22:15	11.22	72%	37.7°
2038-01-16 Sat	26	—	unknown	19:25–01:40 (marginal, 6.25 h)	42.9° 22:15	11.2	81%	30.3°
2038-01-17 Sun	17	—	unknown	23:20–01:10 (marginal, 1.83 h)	42.9° 22:10	11.18	88%	26.4°
2038-01-18 Mon	12	—	unknown	—	42.9° 22:05	11.15	94%	28.0°
2038-01-19 Tue	14	—	unknown	19:10–20:05 (marginal, 0.92 h)	42.9° 22:00	11.13	98%	34.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-12-21&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.