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: 12-19 (18), 12-20 (15), 12-21 (13), 12-25 (13), 12-26 (13) — by astronomy; check the weather when the night is within four days.

2031-12-19astronomy score per night — click a bar for that night2032-01-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2032-01-08 Thu	1	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.36	20%	77.7°
2032-01-09 Fri	1	—	unknown	—	71.1° 13:10	11.35	12%	66.8°
2032-01-10 Sat	1	—	unknown	—	71.1° 13:05	11.33	5%	56.2°
2032-01-11 Sun	1	—	unknown	—	71.1° 13:00	11.31	1%	46.8°
2032-01-12 Mon	1	—	unknown	—	71.1° 12:55	11.3	0%	39.9°
2032-01-13 Tue	0	—	unknown	—	71.1° 12:55	11.28	2%	37.2°
2032-01-14 Wed	0	—	unknown	—	71.1° 12:50	11.26	7%	39.6°
2032-01-15 Thu	0	—	unknown	—	71.1° 12:45	11.23	14%	46.3°
2032-01-16 Fri	0	—	unknown	—	71.1° 12:40	11.21	23%	55.2°
2032-01-17 Sat	0	—	unknown	—	71.1° 12:35	11.19	33%	65.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-12-19&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.