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: 09-27 (100), 09-28 (100), 09-29 (100), 09-30 (100), 10-01 (100) — by astronomy; check the weather when the night is within four days.

2037-09-18astronomy score per night — click a bar for that night2037-10-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-09-18 Fri	82	—	unknown	21:00–02:40 (good, 5.67 h)	71.1° 21:30	8.55	74%	43.7°
2037-09-19 Sat	51	—	unknown	21:00–03:00 (marginal, 6.0 h)	71.1° 21:25	8.6	82%	43.1°
2037-09-20 Sun	45	—	unknown	20:55–02:45 (marginal, 5.83 h)	71.1° 21:25	8.65	89%	45.2°
2037-09-21 Mon	44	—	unknown	20:55–02:35 (marginal, 5.67 h)	71.1° 21:20	8.7	94%	49.5°
2037-09-22 Tue	45	—	unknown	20:55–02:30 (marginal, 5.58 h)	71.1° 21:15	8.75	98%	55.5°
2037-09-23 Wed	51	—	unknown	20:50–21:45 (good, 0.92 h)	71.1° 21:10	8.8	100%	62.7°
2037-09-24 Thu	59	—	unknown	20:50–23:05 (good, 2.25 h)	71.1° 21:10	8.85	100%	70.6°
2037-09-25 Fri	69	—	unknown	20:50–23:55 (good, 3.08 h)	71.1° 21:05	8.9	98%	78.9°
2037-09-26 Sat	81	—	unknown	20:45–00:45 (good, 4.0 h)	71.1° 21:00	8.95	94%	87.6°
2037-09-27 Sun	100	—	unknown	20:45–01:30 (good, 4.75 h)	71.1° 20:55	9.0	89%	96.3°
2037-09-28 Mon	100	—	unknown	20:45–01:40 (good, 4.92 h)	71.1° 20:50	9.05	83%	105.1°
2037-09-29 Tue	100	—	unknown	20:40–01:45 (good, 5.08 h)	71.1° 20:50	9.1	75%	113.6°
2037-09-30 Wed	100	—	unknown	20:40–01:45 (good, 5.08 h)	71.1° 20:45	9.15	66%	121.5°
2037-10-01 Thu	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:40	9.2	55%	128.6°
2037-10-02 Fri	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.24	45%	133.9°
2037-10-03 Sat	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.29	34%	136.7°
2037-10-04 Sun	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:30	9.34	24%	136.0°
2037-10-05 Mon	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:25	9.38	15%	131.8°
2037-10-06 Tue	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.43	7%	124.7°
2037-10-07 Wed	100	—	unknown	20:25–01:25 (good, 5.0 h)	71.1° 20:15	9.48	2%	115.5°
2037-10-08 Thu	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.52	0%	105.1°
2037-10-09 Fri	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.57	1%	94.2°
2037-10-10 Sat	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.61	5%	83.3°
2037-10-11 Sun	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.66	11%	72.9°
2037-10-12 Mon	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 19:55	9.7	20%	63.3°
2037-10-13 Tue	98	—	unknown	20:15–01:00 (good, 4.75 h)	71.1° 19:55	9.75	29%	55.1°
2037-10-14 Wed	91	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:50	9.79	39%	48.7°
2037-10-15 Thu	84	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:45	9.84	49%	44.6°
2037-10-16 Fri	62	—	unknown	20:15–00:25 (good, 4.17 h)	71.1° 19:40	9.88	59%	43.2°
2037-10-17 Sat	51	—	unknown	20:10–23:05 (good, 2.92 h)	71.1° 19:35	9.92	68%	44.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-09-18&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.