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: 12-21 (89), 12-22 (89), 12-23 (89), 12-24 (89), 12-25 (89) — by astronomy; check the weather when the night is within four days.

2033-12-21astronomy score per night — click a bar for that night2034-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2033-12-21 Wed	89	—	unknown	20:40–03:15 (good, 6.58 h)	42.9° 23:55	11.51	0%	154.8°
2033-12-22 Thu	89	—	unknown	20:35–03:10 (good, 6.58 h)	42.9° 23:50	11.51	2%	148.4°
2033-12-23 Fri	89	—	unknown	20:35–03:05 (good, 6.5 h)	42.9° 23:45	11.5	5%	138.9°
2033-12-24 Sat	89	—	unknown	20:30–03:00 (good, 6.5 h)	42.9° 23:45	11.5	11%	127.9°
2033-12-25 Sun	89	—	unknown	20:25–03:00 (good, 6.58 h)	42.9° 23:40	11.5	18%	116.0°
2033-12-26 Mon	89	—	unknown	20:25–02:55 (good, 6.5 h)	42.9° 23:35	11.49	28%	103.7°
2033-12-27 Tue	89	—	unknown	20:30–02:50 (good, 6.33 h)	42.9° 23:30	11.49	38%	91.1°
2033-12-28 Wed	88	—	unknown	20:35–02:45 (good, 6.17 h)	42.9° 23:25	11.48	49%	78.3°
2033-12-29 Thu	83	—	unknown	21:20–02:45 (good, 5.42 h)	42.9° 23:25	11.48	60%	65.5°
2033-12-30 Fri	60	—	unknown	00:50–02:05 (good, 1.25 h)	42.9° 23:20	11.47	71%	52.9°
2033-12-31 Sat	38	—	unknown	20:10–03:00 (marginal, 6.83 h)	42.9° 23:15	11.46	81%	41.0°
2034-01-01 Sun	21	—	unknown	22:55–02:30 (marginal, 3.58 h)	42.9° 23:10	11.45	89%	30.8°
2034-01-02 Mon	13	—	unknown	—	42.9° 23:10	11.44	95%	24.5°
2034-01-03 Tue	11	—	unknown	—	42.9° 23:05	11.43	99%	25.2°
2034-01-04 Wed	14	—	unknown	20:05–21:00 (marginal, 0.92 h)	42.9° 23:00	11.41	100%	32.3°
2034-01-05 Thu	26	—	unknown	19:30–00:20 (marginal, 4.83 h)	42.9° 22:55	11.4	98%	42.4°
2034-01-06 Fri	42	—	unknown	19:05–02:00 (marginal, 6.92 h)	42.9° 22:50	11.39	95%	53.5°
2034-01-07 Sat	81	—	unknown	19:35–21:55 (good, 2.33 h)	42.9° 22:50	11.37	89%	65.0°
2034-01-08 Sun	86	—	unknown	19:30–00:25 (good, 4.92 h)	42.9° 22:45	11.36	82%	76.5°
2034-01-09 Mon	88	—	unknown	19:25–01:30 (good, 6.08 h)	42.9° 22:40	11.34	74%	87.8°
2034-01-10 Tue	89	—	unknown	19:20–01:40 (good, 6.33 h)	42.9° 22:35	11.32	65%	98.8°
2034-01-11 Wed	89	—	unknown	19:20–01:45 (good, 6.42 h)	42.9° 22:30	11.3	56%	109.7°
2034-01-12 Thu	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:30	11.29	46%	120.3°
2034-01-13 Fri	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.27	37%	130.6°
2034-01-14 Sat	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.24	28%	140.3°
2034-01-15 Sun	89	—	unknown	19:00–01:35 (good, 6.58 h)	42.9° 22:15	11.22	20%	148.9°
2034-01-16 Mon	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:15	11.2	13%	154.9°
2034-01-17 Tue	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:10	11.18	7%	155.9°
2034-01-18 Wed	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:05	11.16	3%	151.0°
2034-01-19 Thu	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:00	11.13	0%	142.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2033-12-21&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.