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: 09-15 (36), 09-14 (35), 09-13 (33), 09-12 (31), 09-11 (30) — by astronomy; check the weather when the night is within four days.

2029-08-17astronomy score per night — click a bar for that night2029-09-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-08-17 Fri	0	—	unknown	—	42.9° 09:10	6.77	63%	146.9°
2029-08-18 Sat	0	—	unknown	—	42.9° 09:05	6.83	73%	150.5°
2029-08-19 Sun	1	—	unknown	—	42.9° 09:00	6.89	82%	148.5°
2029-08-20 Mon	1	—	unknown	—	42.9° 09:00	6.95	90%	142.1°
2029-08-21 Tue	1	—	unknown	—	42.9° 08:55	7.0	95%	133.3°
2029-08-22 Wed	1	—	unknown	—	42.9° 08:50	7.06	98%	123.2°
2029-08-23 Thu	1	—	unknown	—	42.9° 08:45	7.12	100%	112.7°
2029-08-24 Fri	1	—	unknown	—	42.9° 08:45	7.17	99%	102.0°
2029-08-25 Sat	2	—	unknown	04:55–05:05 (marginal, 0.17 h)	42.9° 08:40	7.23	96%	91.3°
2029-08-26 Sun	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:35	7.29	92%	80.8°
2029-08-27 Mon	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:30	7.35	86%	70.5°
2029-08-28 Tue	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:25	7.4	79%	60.5°
2029-08-29 Wed	2	—	unknown	05:00–05:10 (marginal, 0.17 h)	42.9° 08:25	7.46	71%	51.0°
2029-08-30 Thu	3	—	unknown	04:50–05:10 (marginal, 0.33 h)	42.9° 08:20	7.51	62%	42.3°
2029-08-31 Fri	4	—	unknown	04:40–05:10 (marginal, 0.5 h)	42.9° 08:15	7.57	52%	35.0°
2029-09-01 Sat	6	—	unknown	04:30–05:10 (marginal, 0.67 h)	42.9° 08:10	7.63	43%	30.3°
2029-09-02 Sun	9	—	unknown	04:20–05:15 (marginal, 0.92 h)	42.9° 08:05	7.68	33%	29.7°
2029-09-03 Mon	12	—	unknown	05:05–05:15 (good, 0.17 h)	42.9° 08:05	7.74	24%	33.8°
2029-09-04 Tue	15	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:00	7.79	16%	41.4°
2029-09-05 Wed	19	—	unknown	04:45–05:20 (good, 0.58 h)	42.9° 07:55	7.85	8%	51.4°
2029-09-06 Thu	22	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.9	3%	62.8°
2029-09-07 Fri	23	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.96	0%	75.0°
2029-09-08 Sat	24	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:45	8.01	0%	87.8°
2029-09-09 Sun	26	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.07	3%	100.8°
2029-09-10 Mon	28	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.12	9%	113.6°
2029-09-11 Tue	30	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:30	8.17	17%	125.8°
2029-09-12 Wed	31	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.23	27%	136.8°
2029-09-13 Thu	33	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:25	8.28	37%	145.5°
2029-09-14 Fri	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.33	48%	150.3°
2029-09-15 Sat	36	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.39	60%	149.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-08-17&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.