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: 01-25 (89), 01-26 (89), 01-27 (89), 01-28 (89), 01-29 (89) — by astronomy; check the weather when the night is within four days.

2046-01-20astronomy score per night — click a bar for that night2046-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-01-20 Sat	13	—	unknown	19:15–19:30 (marginal, 0.25 h)	42.9° 21:55	11.1	96%	35.3°
2046-01-21 Sun	19	—	unknown	19:00–22:05 (marginal, 3.08 h)	42.9° 21:55	11.08	100%	42.4°
2046-01-22 Mon	31	—	unknown	19:05–00:40 (marginal, 5.58 h)	42.9° 21:50	11.05	100%	52.5°
2046-01-23 Tue	48	—	unknown	19:05–01:05 (marginal, 6.0 h)	42.9° 21:45	11.02	97%	64.1°
2046-01-24 Wed	86	—	unknown	19:05–22:45 (good, 3.67 h)	42.9° 21:40	11.0	92%	76.4°
2046-01-25 Thu	89	—	unknown	19:05–00:25 (good, 5.33 h)	42.9° 21:35	10.97	84%	88.8°
2046-01-26 Fri	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:35	10.94	74%	101.0°
2046-01-27 Sat	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:30	10.91	64%	112.8°
2046-01-28 Sun	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.88	53%	123.7°
2046-01-29 Mon	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.85	42%	133.3°
2046-01-30 Tue	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:20	10.82	32%	141.2°
2046-01-31 Wed	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.79	22%	146.1°
2046-02-01 Thu	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.75	15%	147.1°
2046-02-02 Fri	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.72	8%	144.1°
2046-02-03 Sat	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.69	4%	138.0°
2046-02-04 Sun	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 21:00	10.65	1%	130.1°
2046-02-05 Mon	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.62	0%	121.2°
2046-02-06 Tue	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.58	1%	111.7°
2046-02-07 Wed	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.54	4%	102.0°
2046-02-08 Thu	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:40	10.51	8%	92.0°
2046-02-09 Fri	88	—	unknown	19:25–00:00 (good, 4.58 h)	42.9° 20:40	10.47	14%	82.1°
2046-02-10 Sat	85	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.43	21%	72.2°
2046-02-11 Sun	75	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.4	29%	62.5°
2046-02-12 Mon	61	—	unknown	19:25–23:30 (good, 4.08 h)	42.9° 20:25	10.36	38%	53.1°
2046-02-13 Tue	47	—	unknown	19:30–23:10 (good, 3.67 h)	42.9° 20:25	10.32	48%	44.5°
2046-02-14 Wed	33	—	unknown	19:30–00:05 (marginal, 4.58 h)	42.9° 20:20	10.28	58%	37.4°
2046-02-15 Thu	22	—	unknown	19:30–23:45 (marginal, 4.25 h)	42.9° 20:15	10.24	68%	33.2°
2046-02-16 Fri	15	—	unknown	19:30–23:20 (marginal, 3.83 h)	42.9° 20:10	10.2	78%	33.5°
2046-02-17 Sat	13	—	unknown	19:30–22:55 (marginal, 3.42 h)	42.9° 20:05	10.16	87%	38.7°
2046-02-18 Sun	15	—	unknown	19:35–22:55 (marginal, 3.33 h)	42.9° 20:05	10.12	94%	47.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-01-20&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.