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: 09-26 (100), 09-27 (100), 09-28 (100), 09-29 (100), 09-30 (100) — by astronomy; check the weather when the night is within four days.

2027-09-22astronomy score per night — click a bar for that night2027-10-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-22 Wed	59	—	unknown	01:10–04:10 (good, 3.0 h)	72.5° 05:00	8.72	56%	23.4°
2027-09-23 Thu	75	—	unknown	00:10–05:40 (good, 5.5 h)	72.5° 05:00	8.77	44%	37.3°
2027-09-24 Fri	87	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.82	33%	51.4°
2027-09-25 Sat	97	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:50	8.87	23%	65.8°
2027-09-26 Sun	100	—	unknown	23:40–05:45 (good, 6.08 h)	72.5° 04:45	8.92	14%	80.4°
2027-09-27 Mon	100	—	unknown	23:35–05:45 (good, 6.17 h)	72.5° 04:45	8.97	7%	95.1°
2027-09-28 Tue	100	—	unknown	23:35–05:45 (good, 6.17 h)	72.5° 04:40	9.02	2%	109.8°
2027-09-29 Wed	100	—	unknown	23:30–05:45 (good, 6.25 h)	72.5° 04:35	9.07	0%	124.4°
2027-09-30 Thu	100	—	unknown	23:25–05:45 (good, 6.33 h)	72.5° 04:30	9.12	1%	138.8°
2027-10-01 Fri	100	—	unknown	23:20–05:50 (good, 6.5 h)	72.5° 04:25	9.17	4%	152.9°
2027-10-02 Sat	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:25	9.22	10%	166.5°
2027-10-03 Sun	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:20	9.26	17%	179.3°
2027-10-04 Mon	100	—	unknown	23:10–05:50 (good, 6.67 h)	72.5° 04:15	9.31	26%	167.3°
2027-10-05 Tue	100	—	unknown	23:05–05:55 (good, 6.83 h)	72.5° 04:10	9.36	35%	154.8°
2027-10-06 Wed	100	—	unknown	23:00–05:55 (good, 6.92 h)	72.5° 04:05	9.4	44%	142.6°
2027-10-07 Thu	100	—	unknown	23:00–05:55 (good, 6.92 h)	72.5° 04:05	9.45	54%	130.7°
2027-10-08 Fri	100	—	unknown	23:00–05:55 (good, 6.92 h)	72.5° 04:00	9.5	63%	118.8°
2027-10-09 Sat	100	—	unknown	23:00–05:55 (good, 6.92 h)	72.5° 03:55	9.54	72%	106.9°
2027-10-10 Sun	100	—	unknown	23:05–06:00 (good, 6.92 h)	72.5° 03:50	9.59	80%	95.1°
2027-10-11 Mon	100	—	unknown	23:50–06:00 (good, 6.17 h)	72.5° 03:50	9.63	87%	83.1°
2027-10-12 Tue	100	—	unknown	01:20–06:00 (good, 4.67 h)	72.5° 03:45	9.68	93%	70.9°
2027-10-13 Wed	68	—	unknown	04:10–06:00 (good, 1.83 h)	72.5° 03:40	9.72	97%	58.6°
2027-10-14 Thu	47	—	unknown	22:50–06:05 (marginal, 7.25 h)	72.5° 03:35	9.77	99%	46.0°
2027-10-15 Fri	27	—	unknown	03:10–06:05 (marginal, 2.92 h)	72.5° 03:30	9.81	100%	33.2°
2027-10-16 Sat	21	—	unknown	04:35–06:05 (marginal, 1.5 h)	72.5° 03:30	9.85	98%	20.1°
2027-10-17 Sun	21	—	unknown	22:35–00:20 (marginal, 1.75 h)	72.5° 03:25	9.9	94%	6.9°
2027-10-18 Mon	29	—	unknown	22:10–06:05 (marginal, 7.92 h)	72.5° 03:20	9.94	88%	6.6°
2027-10-19 Tue	43	—	unknown	21:55–06:10 (marginal, 8.25 h)	72.5° 03:15	9.98	80%	20.3°
2027-10-20 Wed	58	—	unknown	21:40–06:10 (marginal, 8.5 h)	72.5° 03:10	10.02	70%	34.1°
2027-10-21 Thu	85	—	unknown	22:00–05:35 (good, 7.58 h)	72.5° 03:10	10.07	59%	48.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-22&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.