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: 10-18 (89), 10-19 (89), 10-17 (88), 10-16 (82), 10-15 (70) — by astronomy; check the weather when the night is within four days.

2044-09-20astronomy score per night — click a bar for that night2044-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-09-20 Tue	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.67	0%	88.4°
2044-09-21 Wed	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:50	8.72	0%	99.9°
2044-09-22 Thu	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.77	3%	111.0°
2044-09-23 Fri	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.82	7%	121.3°
2044-09-24 Sat	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.87	13%	130.6°
2044-09-25 Sun	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.92	21%	138.4°
2044-09-26 Mon	56	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:30	8.97	29%	143.9°
2044-09-27 Tue	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.02	38%	146.2°
2044-09-28 Wed	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.07	48%	144.9°
2044-09-29 Thu	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.11	57%	140.4°
2044-09-30 Fri	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.16	66%	133.6°
2044-10-01 Sat	65	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.21	75%	125.3°
2044-10-02 Sun	65	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:10	9.26	83%	116.1°
2044-10-03 Mon	63	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:05	9.31	90%	106.1°
2044-10-04 Tue	59	—	unknown	03:15–05:55 (good, 2.67 h)	42.9° 06:00	9.35	95%	95.6°
2044-10-05 Wed	40	—	unknown	04:10–05:55 (good, 1.75 h)	42.9° 05:55	9.4	99%	84.8°
2044-10-06 Thu	30	—	unknown	02:30–06:25 (marginal, 3.92 h)	42.9° 05:55	9.45	100%	73.9°
2044-10-07 Fri	22	—	unknown	02:40–05:55 (marginal, 3.25 h)	42.9° 05:50	9.49	99%	63.0°
2044-10-08 Sat	16	—	unknown	02:50–05:55 (marginal, 3.08 h)	42.9° 05:45	9.54	96%	52.6°
2044-10-09 Sun	13	—	unknown	02:55–06:00 (marginal, 3.08 h)	42.9° 05:40	9.58	90%	43.4°
2044-10-10 Mon	13	—	unknown	02:40–06:00 (marginal, 3.33 h)	42.9° 05:35	9.63	82%	36.5°
2044-10-11 Tue	17	—	unknown	02:15–06:00 (marginal, 3.75 h)	42.9° 05:35	9.67	72%	33.7°
2044-10-12 Wed	27	—	unknown	01:55–06:00 (marginal, 4.08 h)	42.9° 05:30	9.72	61%	36.0°
2044-10-13 Thu	40	—	unknown	03:35–05:05 (good, 1.5 h)	42.9° 05:25	9.76	50%	42.5°
2044-10-14 Fri	55	—	unknown	02:25–06:05 (good, 3.67 h)	42.9° 05:20	9.81	39%	51.6°
2044-10-15 Sat	70	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.85	28%	62.0°
2044-10-16 Sun	82	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.89	18%	73.2°
2044-10-17 Mon	88	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.93	11%	84.6°
2044-10-18 Tue	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	9.98	5%	95.9°
2044-10-19 Wed	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:00	10.02	1%	107.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-09-20&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.