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 Seven Sisters: 08-31 (100), 09-01 (100), 09-02 (100), 09-03 (100), 09-04 (100) — by astronomy; check the weather when the night is within four days.

2041-08-21astronomy score per night — click a bar for that night2041-09-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-08-21 Wed	63	—	unknown	02:00–04:55 (good, 2.92 h)	72.5° 07:05	7.01	20%	36.9°
2041-08-22 Thu	74	—	unknown	01:55–05:00 (good, 3.08 h)	72.5° 07:05	7.07	12%	49.1°
2041-08-23 Fri	80	—	unknown	01:55–05:00 (good, 3.08 h)	72.5° 07:00	7.12	7%	61.1°
2041-08-24 Sat	86	—	unknown	01:50–05:00 (good, 3.17 h)	72.5° 06:55	7.18	3%	73.0°
2041-08-25 Sun	89	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:50	7.24	1%	84.9°
2041-08-26 Mon	90	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:45	7.29	0%	96.7°
2041-08-27 Tue	92	—	unknown	01:35–05:05 (good, 3.5 h)	72.5° 06:45	7.35	2%	108.5°
2041-08-28 Wed	95	—	unknown	01:35–05:05 (good, 3.5 h)	72.5° 06:40	7.41	5%	120.3°
2041-08-29 Thu	97	—	unknown	01:30–05:10 (good, 3.67 h)	72.5° 06:35	7.46	9%	132.2°
2041-08-30 Fri	98	—	unknown	01:25–05:10 (good, 3.75 h)	72.5° 06:30	7.52	16%	144.2°
2041-08-31 Sat	100	—	unknown	01:20–05:10 (good, 3.83 h)	72.5° 06:25	7.58	23%	156.3°
2041-09-01 Sun	100	—	unknown	01:15–05:15 (good, 4.0 h)	72.5° 06:25	7.63	32%	168.6°
2041-09-02 Mon	100	—	unknown	01:15–05:15 (good, 4.0 h)	72.5° 06:20	7.69	42%	177.4°
2041-09-03 Tue	100	—	unknown	01:10–05:15 (good, 4.08 h)	72.5° 06:15	7.74	52%	165.4°
2041-09-04 Wed	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:10	7.8	63%	152.1°
2041-09-05 Thu	100	—	unknown	01:05–05:20 (good, 4.25 h)	72.5° 06:10	7.85	73%	138.3°
2041-09-06 Fri	100	—	unknown	01:05–05:20 (good, 4.25 h)	72.5° 06:05	7.91	83%	124.1°
2041-09-07 Sat	100	—	unknown	01:05–05:20 (good, 4.25 h)	72.5° 06:00	7.96	91%	109.4°
2041-09-08 Sun	96	—	unknown	01:15–05:20 (good, 4.08 h)	72.5° 05:55	8.02	96%	94.4°
2041-09-09 Mon	60	—	unknown	02:45–05:25 (good, 2.67 h)	72.5° 05:50	8.07	100%	79.2°
2041-09-10 Tue	41	—	unknown	05:15–05:25 (good, 0.17 h)	72.5° 05:50	8.13	100%	63.9°
2041-09-11 Wed	27	—	unknown	00:45–05:25 (marginal, 4.67 h)	72.5° 05:45	8.18	96%	48.8°
2041-09-12 Thu	18	—	unknown	00:50–05:25 (marginal, 4.58 h)	72.5° 05:40	8.23	91%	34.0°
2041-09-13 Fri	20	—	unknown	00:35–05:30 (marginal, 4.92 h)	72.5° 05:35	8.29	83%	19.6°
2041-09-14 Sat	28	—	unknown	00:15–05:30 (marginal, 5.25 h)	72.5° 05:30	8.34	74%	5.9°
2041-09-15 Sun	41	—	unknown	00:00–05:30 (marginal, 5.5 h)	72.5° 05:30	8.39	63%	8.2°
2041-09-16 Mon	57	—	unknown	01:15–05:10 (good, 3.92 h)	72.5° 05:25	8.44	53%	21.0°
2041-09-17 Tue	74	—	unknown	00:30–05:35 (good, 5.08 h)	72.5° 05:20	8.5	43%	33.6°
2041-09-18 Wed	84	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.55	33%	46.0°
2041-09-19 Thu	91	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:15	8.6	25%	58.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-08-21&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.