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: 09-23 (50), 09-22 (48), 09-21 (45), 09-20 (44), 09-19 (43) — by astronomy; check the weather when the night is within four days.

2034-08-25astronomy score per night — click a bar for that night2034-09-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-08-25 Fri	3	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.22	84%	147.4°
2034-08-26 Sat	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.28	91%	137.8°
2034-08-27 Sun	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.33	96%	126.8°
2034-08-28 Mon	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.39	99%	114.9°
2034-08-29 Tue	5	—	unknown	04:40–05:10 (marginal, 0.5 h)	42.9° 08:25	7.45	100%	102.4°
2034-08-30 Wed	5	—	unknown	04:40–05:10 (marginal, 0.5 h)	42.9° 08:20	7.5	98%	89.5°
2034-08-31 Thu	4	—	unknown	04:45–05:10 (marginal, 0.42 h)	42.9° 08:15	7.56	94%	76.4°
2034-09-01 Fri	4	—	unknown	04:50–05:10 (marginal, 0.33 h)	42.9° 08:10	7.61	87%	63.4°
2034-09-02 Sat	4	—	unknown	04:50–05:15 (marginal, 0.42 h)	42.9° 08:10	7.67	78%	50.8°
2034-09-03 Sun	4	—	unknown	04:45–05:15 (marginal, 0.5 h)	42.9° 08:05	7.73	68%	39.0°
2034-09-04 Mon	6	—	unknown	04:30–05:15 (marginal, 0.75 h)	42.9° 08:00	7.78	56%	29.1°
2034-09-05 Tue	9	—	unknown	04:15–05:15 (marginal, 1.0 h)	42.9° 07:55	7.84	45%	23.7°
2034-09-06 Wed	13	—	unknown	05:05–05:20 (good, 0.25 h)	42.9° 07:55	7.89	34%	25.4°
2034-09-07 Thu	17	—	unknown	04:50–05:20 (good, 0.5 h)	42.9° 07:50	7.95	24%	33.0°
2034-09-08 Fri	21	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:45	8.0	15%	43.4°
2034-09-09 Sat	25	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.05	8%	54.8°
2034-09-10 Sun	28	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:35	8.11	3%	66.6°
2034-09-11 Mon	29	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.16	1%	78.4°
2034-09-12 Tue	30	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.22	0%	90.1°
2034-09-13 Wed	33	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:25	8.27	2%	101.6°
2034-09-14 Thu	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.32	5%	112.9°
2034-09-15 Fri	36	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:15	8.38	10%	123.7°
2034-09-16 Sat	37	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.43	17%	134.0°
2034-09-17 Sun	39	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:10	8.48	24%	143.4°
2034-09-18 Mon	41	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.53	33%	151.3°
2034-09-19 Tue	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.58	42%	156.0°
2034-09-20 Wed	44	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.64	51%	155.7°
2034-09-21 Thu	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.69	61%	150.3°
2034-09-22 Fri	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.74	71%	141.7°
2034-09-23 Sat	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.79	79%	131.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-08-25&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.