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: 10-17 (89), 10-18 (89), 10-19 (89), 10-20 (89), 10-16 (88) — by astronomy; check the weather when the night is within four days.

2036-09-21astronomy score per night — click a bar for that night2036-10-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-09-21 Sun	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:50	8.71	5%	119.9°
2036-09-22 Mon	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.76	11%	131.9°
2036-09-23 Tue	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.81	19%	142.6°
2036-09-24 Wed	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.86	27%	151.0°
2036-09-25 Thu	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.91	37%	155.3°
2036-09-26 Fri	56	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:30	8.96	47%	153.9°
2036-09-27 Sat	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.01	56%	148.0°
2036-09-28 Sun	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.06	66%	139.6°
2036-09-29 Mon	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.11	74%	130.0°
2036-09-30 Tue	63	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:15	9.16	82%	119.9°
2036-10-01 Wed	62	—	unknown	03:10–05:50 (good, 2.67 h)	42.9° 06:10	9.21	89%	109.3°
2036-10-02 Thu	58	—	unknown	03:20–05:50 (good, 2.5 h)	42.9° 06:10	9.25	94%	98.5°
2036-10-03 Fri	42	—	unknown	03:45–05:50 (good, 2.08 h)	42.9° 06:05	9.3	98%	87.4°
2036-10-04 Sat	33	—	unknown	05:10–05:55 (good, 0.75 h)	42.9° 06:00	9.35	100%	76.3°
2036-10-05 Sun	25	—	unknown	02:40–05:55 (marginal, 3.25 h)	42.9° 05:55	9.4	100%	65.1°
2036-10-06 Mon	18	—	unknown	02:50–05:55 (marginal, 3.08 h)	42.9° 05:55	9.44	98%	54.0°
2036-10-07 Tue	13	—	unknown	03:05–05:55 (marginal, 2.83 h)	42.9° 05:50	9.49	93%	43.3°
2036-10-08 Wed	11	—	unknown	03:30–05:55 (marginal, 2.42 h)	42.9° 05:45	9.53	87%	33.7°
2036-10-09 Thu	13	—	unknown	02:45–06:00 (marginal, 3.25 h)	42.9° 05:40	9.58	79%	26.6°
2036-10-10 Fri	18	—	unknown	02:15–06:00 (marginal, 3.75 h)	42.9° 05:35	9.63	70%	24.8°
2036-10-11 Sat	26	—	unknown	01:55–06:00 (marginal, 4.08 h)	42.9° 05:35	9.67	59%	29.6°
2036-10-12 Sun	40	—	unknown	03:00–05:35 (good, 2.58 h)	42.9° 05:30	9.71	48%	38.7°
2036-10-13 Mon	56	—	unknown	02:30–06:05 (good, 3.58 h)	42.9° 05:25	9.76	37%	49.9°
2036-10-14 Tue	70	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.8	26%	62.3°
2036-10-15 Wed	82	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:15	9.85	17%	75.2°
2036-10-16 Thu	88	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.89	9%	88.4°
2036-10-17 Fri	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.93	3%	101.6°
2036-10-18 Sat	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	9.97	1%	114.5°
2036-10-19 Sun	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.02	0%	126.9°
2036-10-20 Mon	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.06	3%	138.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-09-21&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.