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: 09-21 (100), 09-22 (100), 10-04 (100), 10-05 (100), 10-06 (100) — by astronomy; check the weather when the night is within four days.

2031-09-21astronomy score per night — click a bar for that night2031-10-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-09-21 Sun	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:20	8.67	27%	72.7°
2031-09-22 Mon	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:15	8.72	37%	62.3°
2031-09-23 Tue	95	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.77	48%	52.6°
2031-09-24 Wed	87	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.82	60%	44.4°
2031-09-25 Thu	66	—	unknown	20:50–00:50 (good, 4.0 h)	71.1° 21:05	8.87	71%	38.8°
2031-09-26 Fri	41	—	unknown	20:45–02:30 (marginal, 5.75 h)	71.1° 21:00	8.92	81%	37.2°
2031-09-27 Sat	34	—	unknown	20:45–02:15 (marginal, 5.5 h)	71.1° 21:00	8.97	89%	40.3°
2031-09-28 Sun	33	—	unknown	20:45–02:00 (marginal, 5.25 h)	71.1° 20:55	9.02	95%	47.0°
2031-09-29 Mon	38	—	unknown	20:40–01:55 (marginal, 5.25 h)	71.1° 20:50	9.07	99%	56.1°
2031-09-30 Tue	47	—	unknown	20:40–21:25 (good, 0.75 h)	71.1° 20:45	9.12	100%	66.2°
2031-10-01 Wed	60	—	unknown	20:40–23:05 (good, 2.42 h)	71.1° 20:40	9.17	98%	76.9°
2031-10-02 Thu	76	—	unknown	20:35–00:15 (good, 3.67 h)	71.1° 20:40	9.22	95%	87.5°
2031-10-03 Fri	86	—	unknown	20:35–01:15 (good, 4.67 h)	71.1° 20:35	9.27	89%	98.0°
2031-10-04 Sat	100	—	unknown	20:35–01:20 (good, 4.75 h)	71.1° 20:30	9.31	82%	108.0°
2031-10-05 Sun	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:25	9.36	73%	117.4°
2031-10-06 Mon	100	—	unknown	20:30–01:20 (good, 4.83 h)	71.1° 20:20	9.41	64%	125.9°
2031-10-07 Tue	100	—	unknown	20:30–01:20 (good, 4.83 h)	71.1° 20:20	9.45	55%	133.3°
2031-10-08 Wed	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:15	9.5	46%	139.0°
2031-10-09 Thu	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.54	36%	142.4°
2031-10-10 Fri	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:05	9.59	27%	142.7°
2031-10-11 Sat	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.64	19%	139.8°
2031-10-12 Sun	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.68	12%	134.2°
2031-10-13 Mon	100	—	unknown	20:20–01:00 (good, 4.67 h)	71.1° 19:55	9.72	6%	126.6°
2031-10-14 Tue	100	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:50	9.77	2%	117.7°
2031-10-15 Wed	100	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:45	9.81	0%	107.8°
2031-10-16 Thu	100	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:45	9.86	0%	97.3°
2031-10-17 Fri	100	—	unknown	20:10–00:45 (good, 4.58 h)	71.1° 19:40	9.9	3%	86.4°
2031-10-18 Sat	100	—	unknown	20:10–00:40 (good, 4.5 h)	71.1° 19:35	9.94	8%	75.5°
2031-10-19 Sun	100	—	unknown	20:10–00:40 (good, 4.5 h)	71.1° 19:30	9.98	15%	64.7°
2031-10-20 Mon	98	—	unknown	20:10–00:35 (good, 4.42 h)	71.1° 19:25	10.02	24%	54.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-09-21&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.