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: 01-12 (89), 01-13 (89), 01-14 (89), 01-15 (89), 01-29 (89) — by astronomy; check the weather when the night is within four days.

2043-01-12astronomy score per night — click a bar for that night2043-02-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-01-12 Mon	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.29	3%	121.8°
2043-01-13 Tue	89	—	unknown	19:10–01:45 (good, 6.58 h)	42.9° 22:25	11.27	8%	111.2°
2043-01-14 Wed	89	—	unknown	19:10–01:40 (good, 6.5 h)	42.9° 22:20	11.25	15%	99.9°
2043-01-15 Thu	89	—	unknown	19:10–01:35 (good, 6.42 h)	42.9° 22:20	11.23	24%	88.3°
2043-01-16 Fri	87	—	unknown	19:15–01:35 (good, 6.33 h)	42.9° 22:15	11.21	34%	76.7°
2043-01-17 Sat	83	—	unknown	19:25–01:30 (good, 6.08 h)	42.9° 22:10	11.18	45%	65.3°
2043-01-18 Sun	65	—	unknown	20:55–01:00 (good, 4.08 h)	42.9° 22:05	11.16	56%	54.5°
2043-01-19 Mon	47	—	unknown	19:00–01:50 (marginal, 6.83 h)	42.9° 22:00	11.14	67%	44.8°
2043-01-20 Tue	29	—	unknown	19:00–01:30 (marginal, 6.5 h)	42.9° 22:00	11.11	78%	37.3°
2043-01-21 Wed	18	—	unknown	20:55–00:55 (marginal, 4.0 h)	42.9° 21:55	11.09	86%	33.6°
2043-01-22 Thu	13	—	unknown	—	42.9° 21:50	11.06	93%	34.9°
2043-01-23 Fri	16	—	unknown	19:05–21:10 (marginal, 2.08 h)	42.9° 21:45	11.03	98%	40.6°
2043-01-24 Sat	24	—	unknown	19:05–23:40 (marginal, 4.58 h)	42.9° 21:40	11.0	100%	49.1°
2043-01-25 Sun	36	—	unknown	19:05–00:40 (marginal, 5.58 h)	42.9° 21:40	10.98	99%	58.9°
2043-01-26 Mon	51	—	unknown	19:05–01:00 (marginal, 5.92 h)	42.9° 21:35	10.95	97%	69.3°
2043-01-27 Tue	85	—	unknown	19:10–22:50 (good, 3.67 h)	42.9° 21:30	10.92	92%	79.9°
2043-01-28 Wed	88	—	unknown	19:10–00:15 (good, 5.08 h)	42.9° 21:25	10.89	86%	90.3°
2043-01-29 Thu	89	—	unknown	19:10–00:25 (good, 5.25 h)	42.9° 21:25	10.86	79%	100.5°
2043-01-30 Fri	89	—	unknown	19:10–00:25 (good, 5.25 h)	42.9° 21:20	10.83	70%	110.4°
2043-01-31 Sat	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:15	10.79	62%	119.8°
2043-02-01 Sun	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.76	52%	128.6°
2043-02-02 Mon	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.73	43%	136.4°
2043-02-03 Tue	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:05	10.69	34%	142.6°
2043-02-04 Wed	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.66	25%	146.1°
2043-02-05 Thu	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.63	17%	145.9°
2043-02-06 Fri	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.59	10%	141.8°
2043-02-07 Sat	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.55	5%	134.6°
2043-02-08 Sun	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.52	1%	125.4°
2043-02-09 Mon	89	—	unknown	19:25–00:00 (good, 4.58 h)	42.9° 20:40	10.48	0%	114.9°
2043-02-10 Tue	89	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.44	2%	103.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-01-12&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.