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: 12-09 (44), 12-10 (42), 12-11 (40), 12-12 (38), 12-13 (38) — by astronomy; check the weather when the night is within four days.

2031-12-09astronomy score per night — click a bar for that night2032-01-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-12-09 Tue	44	—	unknown	18:35–20:15 (good, 1.67 h)	71.1° 15:10	11.44	23%	105.7°
2031-12-10 Wed	42	—	unknown	18:35–20:15 (good, 1.67 h)	71.1° 15:05	11.45	15%	95.2°
2031-12-11 Thu	40	—	unknown	18:35–20:10 (good, 1.58 h)	71.1° 15:05	11.46	8%	84.2°
2031-12-12 Fri	38	—	unknown	18:35–20:05 (good, 1.5 h)	71.1° 15:00	11.47	3%	73.0°
2031-12-13 Sat	38	—	unknown	18:35–20:00 (good, 1.42 h)	71.1° 14:55	11.48	0%	61.9°
2031-12-14 Sun	36	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 14:50	11.48	0%	51.7°
2031-12-15 Mon	34	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 14:45	11.49	4%	43.2°
2031-12-16 Tue	30	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:45	11.5	10%	38.0°
2031-12-17 Wed	27	—	unknown	18:35–19:40 (good, 1.08 h)	71.1° 14:40	11.5	18%	37.4°
2031-12-18 Thu	22	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:35	11.5	27%	41.5°
2031-12-19 Fri	18	—	unknown	18:35–19:15 (good, 0.67 h)	71.1° 14:30	11.51	38%	48.9°
2031-12-20 Sat	15	—	unknown	18:35–19:00 (good, 0.42 h)	71.1° 14:30	11.51	49%	58.0°
2031-12-21 Sun	13	—	unknown	18:35–19:55 (marginal, 1.33 h)	71.1° 14:25	11.51	60%	67.9°
2031-12-22 Mon	12	—	unknown	18:35–19:50 (marginal, 1.25 h)	71.1° 14:20	11.51	70%	78.2°
2031-12-23 Tue	11	—	unknown	18:40–19:45 (marginal, 1.08 h)	71.1° 14:15	11.51	79%	88.5°
2031-12-24 Wed	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:10	11.5	87%	98.6°
2031-12-25 Thu	13	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:10	11.5	93%	108.4°
2031-12-26 Fri	13	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:05	11.5	97%	117.7°
2031-12-27 Sat	13	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:00	11.49	99%	126.2°
2031-12-28 Sun	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:55	11.49	100%	133.6°
2031-12-29 Mon	11	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:50	11.48	98%	139.3°
2031-12-30 Tue	11	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:50	11.47	96%	142.4°
2031-12-31 Wed	9	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:45	11.46	91%	142.5°
2032-01-01 Thu	8	—	unknown	18:10–19:15 (marginal, 1.08 h)	71.1° 13:40	11.45	85%	139.5°
2032-01-02 Fri	7	—	unknown	18:10–19:10 (marginal, 1.0 h)	71.1° 13:35	11.44	77%	134.1°
2032-01-03 Sat	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:35	11.43	69%	126.8°
2032-01-04 Sun	5	—	unknown	18:10–18:35 (marginal, 0.42 h)	71.1° 13:30	11.42	60%	118.4°
2032-01-05 Mon	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	50%	109.0°
2032-01-06 Tue	3	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.39	40%	99.1°
2032-01-07 Wed	2	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:15	11.38	30%	88.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-12-09&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.