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: 01-16 (89), 01-17 (89), 01-18 (89), 01-19 (89), 01-20 (89) — by astronomy; check the weather when the night is within four days.

2047-01-07astronomy score per night — click a bar for that night2047-02-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-01-07 Mon	31	—	unknown	19:55–02:25 (marginal, 6.5 h)	42.9° 22:50	11.37	83%	40.7°
2047-01-08 Tue	19	—	unknown	22:55–01:55 (marginal, 3.0 h)	42.9° 22:45	11.36	90%	34.4°
2047-01-09 Wed	12	—	unknown	—	42.9° 22:40	11.34	95%	31.5°
2047-01-10 Thu	12	—	unknown	—	42.9° 22:35	11.33	98%	33.1°
2047-01-11 Fri	18	—	unknown	19:25–21:45 (marginal, 2.33 h)	42.9° 22:35	11.31	100%	39.0°
2047-01-12 Sat	29	—	unknown	19:00–00:45 (marginal, 5.75 h)	42.9° 22:30	11.29	99%	47.9°
2047-01-13 Sun	49	—	unknown	18:55–01:40 (marginal, 6.75 h)	42.9° 22:25	11.27	96%	58.4°
2047-01-14 Mon	83	—	unknown	19:10–22:30 (good, 3.33 h)	42.9° 22:20	11.25	90%	69.9°
2047-01-15 Tue	88	—	unknown	19:05–00:40 (good, 5.58 h)	42.9° 22:20	11.23	82%	81.9°
2047-01-16 Wed	89	—	unknown	19:00–01:10 (good, 6.17 h)	42.9° 22:15	11.21	72%	94.0°
2047-01-17 Thu	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:10	11.18	61%	106.1°
2047-01-18 Fri	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:05	11.16	50%	117.8°
2047-01-19 Sat	89	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:00	11.13	39%	128.8°
2047-01-20 Sun	89	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 22:00	11.11	28%	138.4°
2047-01-21 Mon	89	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.08	19%	145.5°
2047-01-22 Tue	89	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.06	11%	148.6°
2047-01-23 Wed	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.03	5%	146.5°
2047-01-24 Thu	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	11.0	1%	140.4°
2047-01-25 Fri	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	10.98	0%	131.8°
2047-01-26 Sat	89	—	unknown	19:10–00:55 (good, 5.75 h)	42.9° 21:35	10.95	1%	122.0°
2047-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.92	4%	111.8°
2047-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.89	8%	101.4°
2047-01-29 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:25	10.86	14%	91.1°
2047-01-30 Wed	88	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.82	22%	80.9°
2047-01-31 Thu	84	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.79	30%	70.9°
2047-02-01 Fri	74	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.76	39%	61.2°
2047-02-02 Sat	62	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 21:05	10.73	48%	51.9°
2047-02-03 Sun	46	—	unknown	19:15–00:55 (marginal, 5.67 h)	42.9° 21:05	10.69	58%	43.5°
2047-02-04 Mon	31	—	unknown	19:15–00:40 (marginal, 5.42 h)	42.9° 21:00	10.66	67%	36.4°
2047-02-05 Tue	20	—	unknown	19:20–00:15 (marginal, 4.92 h)	42.9° 20:55	10.62	76%	32.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-01-07&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.