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: 09-30 (62), 09-29 (60), 09-28 (59), 09-27 (55), 09-26 (50) — by astronomy; check the weather when the night is within four days.

2046-09-01astronomy score per night — click a bar for that night2046-09-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-09-01 Sat	12	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.62	2%	90.8°
2046-09-02 Sun	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.68	7%	103.6°
2046-09-03 Mon	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.73	15%	115.9°
2046-09-04 Tue	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.79	24%	127.2°
2046-09-05 Wed	20	—	unknown	04:45–05:20 (good, 0.58 h)	42.9° 07:55	7.84	34%	137.1°
2046-09-06 Thu	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.9	45%	144.4°
2046-09-07 Fri	23	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.95	56%	147.9°
2046-09-08 Sat	24	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:45	8.01	66%	146.7°
2046-09-09 Sun	26	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.06	75%	141.6°
2046-09-10 Mon	28	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:35	8.11	83%	134.0°
2046-09-11 Tue	29	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.17	90%	125.2°
2046-09-12 Wed	29	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:30	8.22	95%	115.6°
2046-09-13 Thu	24	—	unknown	04:30–05:30 (good, 1.0 h)	42.9° 07:25	8.27	98%	105.7°
2046-09-14 Fri	21	—	unknown	04:40–05:30 (good, 0.83 h)	42.9° 07:20	8.33	100%	95.7°
2046-09-15 Sat	18	—	unknown	03:40–05:30 (marginal, 1.83 h)	42.9° 07:15	8.38	100%	85.6°
2046-09-16 Sun	14	—	unknown	03:45–05:30 (marginal, 1.75 h)	42.9° 07:15	8.43	97%	75.7°
2046-09-17 Mon	12	—	unknown	03:50–05:35 (marginal, 1.75 h)	42.9° 07:10	8.49	94%	65.9°
2046-09-18 Tue	10	—	unknown	03:55–05:35 (marginal, 1.67 h)	42.9° 07:05	8.54	88%	56.4°
2046-09-19 Wed	10	—	unknown	03:55–05:35 (marginal, 1.67 h)	42.9° 07:00	8.59	82%	47.5°
2046-09-20 Thu	10	—	unknown	03:45–05:35 (marginal, 1.83 h)	42.9° 07:00	8.64	73%	39.8°
2046-09-21 Fri	12	—	unknown	03:30–05:35 (marginal, 2.08 h)	42.9° 06:55	8.69	64%	34.1°
2046-09-22 Sat	17	—	unknown	03:15–05:40 (marginal, 2.42 h)	42.9° 06:50	8.74	54%	31.9°
2046-09-23 Sun	24	—	unknown	03:00–05:40 (marginal, 2.67 h)	42.9° 06:45	8.79	44%	34.0°
2046-09-24 Mon	33	—	unknown	03:50–05:40 (good, 1.83 h)	42.9° 06:40	8.84	33%	40.2°
2046-09-25 Tue	41	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:40	8.89	23%	49.3°
2046-09-26 Wed	50	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.94	14%	60.2°
2046-09-27 Thu	55	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	8.99	7%	72.2°
2046-09-28 Fri	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.04	2%	84.8°
2046-09-29 Sat	60	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:20	9.09	0%	97.8°
2046-09-30 Sun	62	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:20	9.14	1%	110.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-09-01&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.