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 HD 189733: 09-07 (100), 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100) — by astronomy; check the weather when the night is within four days.

2027-09-07astronomy score per night — click a bar for that night2027-10-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-07 Tue	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:15	7.93	52%	66.0°
2027-09-08 Wed	99	—	unknown	21:20–03:20 (good, 6.0 h)	71.1° 22:10	7.98	61%	58.1°
2027-09-09 Thu	92	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.04	70%	51.3°
2027-09-10 Fri	84	—	unknown	21:20–03:10 (good, 5.83 h)	71.1° 22:05	8.09	79%	46.1°
2027-09-11 Sat	52	—	unknown	21:15–03:35 (marginal, 6.33 h)	71.1° 22:00	8.15	86%	42.9°
2027-09-12 Sun	42	—	unknown	21:15–03:20 (marginal, 6.08 h)	71.1° 21:55	8.2	92%	42.3°
2027-09-13 Mon	38	—	unknown	21:10–03:05 (marginal, 5.92 h)	71.1° 21:55	8.25	96%	44.3°
2027-09-14 Tue	38	—	unknown	21:10–02:55 (marginal, 5.75 h)	71.1° 21:50	8.31	99%	48.7°
2027-09-15 Wed	42	—	unknown	21:10–02:45 (marginal, 5.58 h)	71.1° 21:45	8.36	100%	54.9°
2027-09-16 Thu	50	—	unknown	21:05–21:50 (good, 0.75 h)	71.1° 21:40	8.41	99%	62.5°
2027-09-17 Fri	62	—	unknown	21:05–23:30 (good, 2.42 h)	71.1° 21:35	8.46	96%	71.1°
2027-09-18 Sat	77	—	unknown	21:00–00:35 (good, 3.58 h)	71.1° 21:35	8.52	91%	80.2°
2027-09-19 Sun	83	—	unknown	21:00–01:40 (good, 4.67 h)	71.1° 21:30	8.57	84%	89.7°
2027-09-20 Mon	100	—	unknown	21:00–02:10 (good, 5.17 h)	71.1° 21:25	8.62	76%	99.4°
2027-09-21 Tue	100	—	unknown	20:55–02:15 (good, 5.33 h)	71.1° 21:20	8.67	66%	109.1°
2027-09-22 Wed	100	—	unknown	20:55–02:15 (good, 5.33 h)	71.1° 21:15	8.72	56%	118.3°
2027-09-23 Thu	100	—	unknown	20:55–02:15 (good, 5.33 h)	71.1° 21:15	8.77	44%	126.6°
2027-09-24 Fri	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.82	33%	133.4°
2027-09-25 Sat	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.87	23%	137.3°
2027-09-26 Sun	100	—	unknown	20:45–02:10 (good, 5.42 h)	71.1° 21:00	8.92	14%	137.5°
2027-09-27 Mon	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.97	7%	133.7°
2027-09-28 Tue	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.02	2%	126.8°
2027-09-29 Wed	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.07	0%	118.0°
2027-09-30 Thu	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.12	1%	108.1°
2027-10-01 Fri	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:40	9.17	4%	98.0°
2027-10-02 Sat	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.22	10%	87.8°
2027-10-03 Sun	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.26	17%	78.1°
2027-10-04 Mon	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.31	26%	68.9°
2027-10-05 Tue	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:25	9.36	35%	60.5°
2027-10-06 Wed	95	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:20	9.4	44%	53.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-07&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.