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: 09-17 (100), 09-18 (100), 09-19 (100), 09-20 (100), 09-21 (100) — by astronomy; check the weather when the night is within four days.

2045-09-17astronomy score per night — click a bar for that night2045-10-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-09-17 Sun	100	—	unknown	00:15–05:35 (good, 5.33 h)	72.6° 05:20	8.5	49%	156.0°
2045-09-18 Mon	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.6° 05:15	8.55	58%	143.7°
2045-09-19 Tue	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.6° 05:15	8.6	68%	131.6°
2045-09-20 Wed	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.6° 05:10	8.65	76%	119.7°
2045-09-21 Thu	100	—	unknown	00:15–05:40 (good, 5.42 h)	72.6° 05:05	8.7	84%	107.9°
2045-09-22 Fri	100	—	unknown	00:20–05:40 (good, 5.33 h)	72.6° 05:00	8.75	90%	96.0°
2045-09-23 Sat	100	—	unknown	01:15–05:40 (good, 4.42 h)	72.6° 04:55	8.81	95%	84.2°
2045-09-24 Sun	71	—	unknown	02:40–05:40 (good, 3.0 h)	72.6° 04:55	8.86	98%	72.2°
2045-09-25 Mon	51	—	unknown	05:15–05:40 (good, 0.42 h)	72.6° 04:50	8.91	100%	60.1°
2045-09-26 Tue	34	—	unknown	23:55–05:45 (marginal, 5.83 h)	72.6° 04:45	8.96	100%	47.9°
2045-09-27 Wed	21	—	unknown	02:30–05:45 (marginal, 3.25 h)	72.6° 04:40	9.0	97%	35.5°
2045-09-28 Thu	18	—	unknown	04:20–05:45 (marginal, 1.42 h)	72.6° 04:35	9.05	93%	22.9°
2045-09-29 Fri	21	—	unknown	23:35–05:45 (marginal, 6.17 h)	72.6° 04:35	9.1	87%	10.2°
2045-09-30 Sat	30	—	unknown	23:15–05:50 (marginal, 6.58 h)	72.6° 04:30	9.15	79%	3.0°
2045-10-01 Sun	44	—	unknown	23:00–05:50 (marginal, 6.83 h)	72.6° 04:25	9.2	70%	16.0°
2045-10-02 Mon	62	—	unknown	00:45–03:00 (good, 2.25 h)	72.6° 04:20	9.25	59%	29.5°
2045-10-03 Tue	81	—	unknown	23:10–05:50 (good, 6.67 h)	72.6° 04:20	9.29	48%	43.2°
2045-10-04 Wed	91	—	unknown	23:10–05:55 (good, 6.75 h)	72.6° 04:15	9.34	37%	57.2°
2045-10-05 Thu	100	—	unknown	23:05–05:55 (good, 6.83 h)	72.6° 04:10	9.39	26%	71.5°
2045-10-06 Fri	100	—	unknown	23:00–05:55 (good, 6.92 h)	72.6° 04:05	9.43	17%	86.1°
2045-10-07 Sat	100	—	unknown	22:55–05:55 (good, 7.0 h)	72.6° 04:00	9.48	9%	100.8°
2045-10-08 Sun	100	—	unknown	22:50–05:55 (good, 7.08 h)	72.6° 04:00	9.53	3%	115.6°
2045-10-09 Mon	100	—	unknown	22:50–06:00 (good, 7.17 h)	72.6° 03:55	9.57	0%	130.3°
2045-10-10 Tue	100	—	unknown	22:45–06:00 (good, 7.25 h)	72.6° 03:50	9.62	0%	144.8°
2045-10-11 Wed	100	—	unknown	22:40–06:00 (good, 7.33 h)	72.6° 03:45	9.66	3%	159.1°
2045-10-12 Thu	100	—	unknown	22:35–06:00 (good, 7.42 h)	72.6° 03:40	9.71	8%	172.9°
2045-10-13 Fri	100	—	unknown	22:30–06:00 (good, 7.5 h)	72.6° 03:40	9.75	15%	173.5°
2045-10-14 Sat	100	—	unknown	22:30–06:05 (good, 7.58 h)	72.6° 03:35	9.79	23%	160.5°
2045-10-15 Sun	100	—	unknown	22:25–06:05 (good, 7.67 h)	72.6° 03:30	9.84	32%	147.8°
2045-10-16 Mon	100	—	unknown	22:25–06:05 (good, 7.67 h)	72.6° 03:25	9.88	42%	135.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-09-17&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.