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: 02-06 (3), 02-07 (3), 02-03 (2), 02-04 (2), 02-05 (2) — by astronomy; check the weather when the night is within four days.

2031-01-09astronomy score per night — click a bar for that night2031-02-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-09 Thu	1	—	unknown	—	71.1° 13:10	11.34	99%	141.7°
2031-01-10 Fri	1	—	unknown	—	71.1° 13:05	11.33	96%	142.2°
2031-01-11 Sat	1	—	unknown	—	71.1° 13:00	11.31	91%	139.6°
2031-01-12 Sun	1	—	unknown	—	71.1° 12:55	11.29	84%	134.1°
2031-01-13 Mon	0	—	unknown	—	71.1° 12:50	11.27	76%	126.5°
2031-01-14 Tue	0	—	unknown	—	71.1° 12:50	11.25	67%	117.6°
2031-01-15 Wed	0	—	unknown	—	71.1° 12:45	11.23	56%	107.7°
2031-01-16 Thu	0	—	unknown	—	71.1° 12:40	11.21	46%	97.2°
2031-01-17 Fri	0	—	unknown	—	71.1° 12:35	11.19	35%	86.2°
2031-01-18 Sat	0	—	unknown	—	71.1° 12:35	11.16	24%	75.0°
2031-01-19 Sun	0	—	unknown	—	71.1° 12:30	11.14	15%	63.9°
2031-01-20 Mon	0	—	unknown	—	71.1° 12:25	11.11	7%	53.5°
2031-01-21 Tue	0	—	unknown	—	71.1° 12:20	11.09	2%	44.7°
2031-01-22 Wed	0	—	unknown	—	71.1° 12:15	11.06	0%	39.0°
2031-01-23 Thu	0	—	unknown	—	71.1° 12:15	11.03	1%	37.7°
2031-01-24 Fri	0	—	unknown	—	71.1° 12:10	11.01	4%	41.2°
2031-01-25 Sat	0	—	unknown	—	71.1° 12:05	10.98	10%	48.0°
2031-01-26 Sun	0	—	unknown	—	71.1° 12:00	10.95	18%	56.7°
2031-01-27 Mon	1	—	unknown	—	71.1° 11:55	10.92	27%	66.3°
2031-01-28 Tue	1	—	unknown	—	71.1° 11:50	10.89	36%	76.1°
2031-01-29 Wed	1	—	unknown	—	71.1° 11:45	10.86	46%	85.9°
2031-01-30 Thu	1	—	unknown	—	71.1° 11:40	10.83	56%	95.6°
2031-01-31 Fri	1	—	unknown	—	71.1° 11:40	10.8	65%	105.0°
2031-02-01 Sat	1	—	unknown	—	71.1° 11:35	10.76	74%	114.0°
2031-02-02 Sun	1	—	unknown	—	71.1° 11:30	10.73	82%	122.5°
2031-02-03 Mon	2	—	unknown	05:55–06:00 (marginal, 0.08 h)	71.1° 11:25	10.7	88%	130.2°
2031-02-04 Tue	2	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:20	10.66	94%	136.6°
2031-02-05 Wed	2	—	unknown	05:50–05:55 (marginal, 0.08 h)	71.1° 11:20	10.63	97%	140.9°
2031-02-06 Thu	3	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:15	10.59	100%	142.4°
2031-02-07 Fri	3	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:10	10.56	100%	140.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-09&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.