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: 01-05 (89), 01-06 (89), 01-07 (89), 01-08 (89), 01-23 (89) — by astronomy; check the weather when the night is within four days.

2030-01-05astronomy score per night — click a bar for that night2030-02-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-01-05 Sat	89	—	unknown	19:40–02:15 (good, 6.58 h)	42.9° 22:55	11.4	4%	129.4°
2030-01-06 Sun	89	—	unknown	19:40–02:10 (good, 6.5 h)	42.9° 22:50	11.39	10%	118.4°
2030-01-07 Mon	89	—	unknown	19:35–02:05 (good, 6.5 h)	42.9° 22:50	11.37	17%	107.2°
2030-01-08 Tue	89	—	unknown	19:35–02:05 (good, 6.5 h)	42.9° 22:45	11.36	25%	96.1°
2030-01-09 Wed	88	—	unknown	19:40–02:00 (good, 6.33 h)	42.9° 22:40	11.34	34%	85.2°
2030-01-10 Thu	85	—	unknown	19:45–01:55 (good, 6.17 h)	42.9° 22:35	11.32	44%	74.6°
2030-01-11 Fri	80	—	unknown	20:10–01:50 (good, 5.67 h)	42.9° 22:30	11.3	53%	64.4°
2030-01-12 Sat	62	—	unknown	22:25–01:20 (good, 2.92 h)	42.9° 22:30	11.29	63%	54.5°
2030-01-13 Sun	46	—	unknown	19:05–02:10 (marginal, 7.08 h)	42.9° 22:25	11.27	71%	45.4°
2030-01-14 Mon	30	—	unknown	19:20–01:55 (marginal, 6.58 h)	42.9° 22:20	11.25	80%	37.3°
2030-01-15 Tue	18	—	unknown	22:15–01:25 (marginal, 3.17 h)	42.9° 22:15	11.22	87%	31.3°
2030-01-16 Wed	12	—	unknown	—	42.9° 22:15	11.2	93%	28.8°
2030-01-17 Thu	12	—	unknown	—	42.9° 22:10	11.18	97%	30.9°
2030-01-18 Fri	17	—	unknown	19:00–21:10 (marginal, 2.17 h)	42.9° 22:05	11.16	99%	37.1°
2030-01-19 Sat	26	—	unknown	19:00–23:50 (marginal, 4.83 h)	42.9° 22:00	11.13	100%	45.9°
2030-01-20 Sun	41	—	unknown	19:00–01:05 (marginal, 6.08 h)	42.9° 21:55	11.11	98%	56.3°
2030-01-21 Mon	80	—	unknown	19:00–21:15 (good, 2.25 h)	42.9° 21:55	11.08	94%	67.5°
2030-01-22 Tue	87	—	unknown	19:05–23:35 (good, 4.5 h)	42.9° 21:50	11.05	88%	79.2°
2030-01-23 Wed	89	—	unknown	19:05–00:40 (good, 5.58 h)	42.9° 21:45	11.03	80%	91.3°
2030-01-24 Thu	89	—	unknown	19:05–00:45 (good, 5.67 h)	42.9° 21:40	11.0	70%	103.4°
2030-01-25 Fri	89	—	unknown	19:05–00:50 (good, 5.75 h)	42.9° 21:35	10.97	59%	115.4°
2030-01-26 Sat	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:35	10.94	48%	127.1°
2030-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.91	37%	137.8°
2030-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.88	26%	146.4°
2030-01-29 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.85	17%	151.1°
2030-01-30 Wed	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:20	10.82	9%	149.7°
2030-01-31 Thu	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.79	4%	143.1°
2030-02-01 Fri	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.76	1%	133.6°
2030-02-02 Sat	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.72	0%	122.9°
2030-02-03 Sun	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.69	2%	111.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-01-05&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.