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: 01-18 (89), 01-19 (89), 01-20 (89), 01-21 (89), 01-22 (89) — by astronomy; check the weather when the night is within four days.

2044-01-12astronomy score per night — click a bar for that night2044-02-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-01-12 Tue	12	—	unknown	—	42.9° 22:30	11.29	95%	33.9°
2044-01-13 Wed	14	—	unknown	19:40–20:15 (marginal, 0.58 h)	42.9° 22:25	11.27	99%	37.9°
2044-01-14 Thu	23	—	unknown	19:05–23:25 (marginal, 4.33 h)	42.9° 22:25	11.25	100%	46.0°
2044-01-15 Fri	37	—	unknown	18:55–01:20 (marginal, 6.42 h)	42.9° 22:20	11.23	98%	56.3°
2044-01-16 Sat	73	—	unknown	19:00–19:30 (good, 0.5 h)	42.9° 22:15	11.21	94%	67.4°
2044-01-17 Sun	86	—	unknown	19:00–23:45 (good, 4.75 h)	42.9° 22:10	11.19	87%	78.8°
2044-01-18 Mon	89	—	unknown	19:00–00:55 (good, 5.92 h)	42.9° 22:05	11.17	79%	90.0°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-01-12&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.