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: 01-19 (89), 01-20 (89), 01-21 (89), 01-22 (89), 01-23 (89) — by astronomy; check the weather when the night is within four days.

2044-01-19astronomy score per night — click a bar for that night2044-02-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-01-19 Tue	89	—	unknown	19:00–01:05 (good, 6.08 h)	42.9° 22:05	11.14	70%	100.8°
2044-01-20 Wed	89	—	unknown	19:00–01:10 (good, 6.17 h)	42.9° 22:00	11.12	60%	111.1°
2044-01-21 Thu	89	—	unknown	19:00–01:10 (good, 6.17 h)	42.9° 21:55	11.09	50%	120.8°
2044-01-22 Fri	89	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.07	41%	129.6°
2044-01-23 Sat	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.04	32%	137.2°
2044-01-24 Sun	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.01	24%	142.9°
2044-01-25 Mon	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	10.98	16%	146.0°
2044-01-26 Tue	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:35	10.95	10%	145.5°
2044-01-27 Wed	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.93	5%	141.6°
2044-01-28 Thu	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:30	10.9	2%	135.1°
2044-01-29 Fri	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.86	0%	126.8°
2044-01-30 Sat	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.83	1%	117.4°
2044-01-31 Sun	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.8	3%	107.3°
2044-02-01 Mon	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.77	8%	96.7°
2044-02-02 Tue	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:10	10.74	14%	85.8°
2044-02-03 Wed	87	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.7	22%	74.9°
2044-02-04 Thu	81	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.67	32%	64.0°
2044-02-05 Fri	66	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:55	10.63	43%	53.6°
2044-02-06 Sat	48	—	unknown	19:20–00:40 (marginal, 5.33 h)	42.9° 20:50	10.6	54%	44.3°
2044-02-07 Sun	31	—	unknown	19:20–00:30 (marginal, 5.17 h)	42.9° 20:50	10.56	65%	37.2°
2044-02-08 Mon	20	—	unknown	19:20–00:05 (marginal, 4.75 h)	42.9° 20:45	10.53	76%	33.9°
2044-02-09 Tue	14	—	unknown	19:25–23:35 (marginal, 4.17 h)	42.9° 20:40	10.49	85%	35.9°
2044-02-10 Wed	15	—	unknown	19:25–22:20 (marginal, 2.92 h)	42.9° 20:35	10.45	92%	42.4°
2044-02-11 Thu	20	—	unknown	19:25–23:25 (marginal, 4.0 h)	42.9° 20:35	10.42	98%	51.7°
2044-02-12 Fri	28	—	unknown	19:25–23:40 (marginal, 4.25 h)	42.9° 20:30	10.38	100%	62.4°
2044-02-13 Sat	41	—	unknown	19:25–20:05 (good, 0.67 h)	42.9° 20:25	10.34	99%	73.8°
2044-02-14 Sun	54	—	unknown	19:30–22:10 (good, 2.67 h)	42.9° 20:20	10.3	96%	85.2°
2044-02-15 Mon	78	—	unknown	19:30–23:10 (good, 3.67 h)	42.9° 20:15	10.26	92%	96.3°
2044-02-16 Tue	83	—	unknown	19:30–23:15 (good, 3.75 h)	42.9° 20:15	10.22	85%	107.1°
2044-02-17 Wed	85	—	unknown	19:30–23:20 (good, 3.83 h)	42.9° 20:10	10.18	77%	117.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-01-19&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.