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: 10-08 (75), 10-07 (72), 10-06 (65), 10-05 (54), 09-21 (47) — by astronomy; check the weather when the night is within four days.

2045-09-09astronomy score per night — click a bar for that night2045-10-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-09-09 Sat	27	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.07	2%	71.0°
2045-09-10 Sun	28	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.13	0%	83.5°
2045-09-11 Mon	30	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:30	8.18	1%	96.0°
2045-09-12 Tue	31	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.23	5%	108.2°
2045-09-13 Wed	33	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:25	8.29	11%	119.7°
2045-09-14 Thu	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.34	20%	130.0°
2045-09-15 Fri	36	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.39	29%	138.6°
2045-09-16 Sat	38	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.45	39%	144.5°
2045-09-17 Sun	40	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:10	8.5	49%	146.9°
2045-09-18 Mon	42	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.55	58%	145.2°
2045-09-19 Tue	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.6	68%	140.2°
2045-09-20 Wed	45	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 06:55	8.65	76%	133.1°
2045-09-21 Thu	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:55	8.7	84%	124.6°
2045-09-22 Fri	47	—	unknown	03:45–05:40 (good, 1.92 h)	42.9° 06:50	8.75	90%	115.5°
2045-09-23 Sat	45	—	unknown	03:50–05:40 (good, 1.83 h)	42.9° 06:45	8.81	95%	105.9°
2045-09-24 Sun	34	—	unknown	03:55–05:40 (good, 1.75 h)	42.9° 06:40	8.86	98%	95.9°
2045-09-25 Mon	28	—	unknown	04:50–05:40 (good, 0.83 h)	42.9° 06:35	8.91	100%	85.8°
2045-09-26 Tue	22	—	unknown	03:05–05:45 (marginal, 2.67 h)	42.9° 06:35	8.96	100%	75.6°
2045-09-27 Wed	17	—	unknown	03:15–05:45 (marginal, 2.5 h)	42.9° 06:30	9.0	97%	65.5°
2045-09-28 Thu	14	—	unknown	03:20–05:45 (marginal, 2.42 h)	42.9° 06:25	9.05	93%	55.7°
2045-09-29 Fri	12	—	unknown	03:25–05:45 (marginal, 2.33 h)	42.9° 06:20	9.1	87%	46.6°
2045-09-30 Sat	12	—	unknown	03:15–05:50 (marginal, 2.58 h)	42.9° 06:15	9.15	79%	39.0°
2045-10-01 Sun	15	—	unknown	02:55–05:50 (marginal, 2.92 h)	42.9° 06:15	9.2	70%	34.1°
2045-10-02 Mon	21	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:10	9.25	59%	33.3°
2045-10-03 Tue	31	—	unknown	02:20–05:50 (marginal, 3.5 h)	42.9° 06:05	9.29	48%	37.2°
2045-10-04 Wed	43	—	unknown	03:10–05:55 (good, 2.75 h)	42.9° 06:00	9.34	37%	44.9°
2045-10-05 Thu	54	—	unknown	02:55–05:55 (good, 3.0 h)	42.9° 06:00	9.39	26%	54.8°
2045-10-06 Fri	65	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.43	17%	66.1°
2045-10-07 Sat	72	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.48	9%	78.2°
2045-10-08 Sun	75	—	unknown	02:30–05:55 (good, 3.42 h)	42.9° 05:45	9.53	3%	90.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-09-09&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.