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 (29), 12-20 (27), 12-21 (25), 12-22 (24), 12-23 (22) — by astronomy; check the weather when the night is within four days.

2043-12-19astronomy score per night — click a bar for that night2044-01-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-12-19 Sat	29	—	unknown	18:35–19:40 (good, 1.08 h)	71.1° 14:30	11.51	82%	134.1°
2043-12-20 Sun	27	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 14:30	11.51	73%	131.3°
2043-12-21 Mon	25	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:25	11.51	63%	126.1°
2043-12-22 Tue	24	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:20	11.51	53%	119.3°
2043-12-23 Wed	22	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.51	43%	111.7°
2043-12-24 Thu	21	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:10	11.5	33%	103.6°
2043-12-25 Fri	19	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	25%	95.4°
2043-12-26 Sat	18	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	17%	87.0°
2043-12-27 Sun	17	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	11%	78.8°
2043-12-28 Mon	15	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 13:55	11.49	6%	70.9°
2043-12-29 Tue	13	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:50	11.48	2%	63.5°
2043-12-30 Wed	11	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:50	11.47	0%	56.8°
2043-12-31 Thu	9	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:45	11.46	0%	51.2°
2044-01-01 Fri	8	—	unknown	18:10–19:15 (marginal, 1.08 h)	71.1° 13:40	11.45	2%	47.3°
2044-01-02 Sat	7	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	6%	45.6°
2044-01-03 Sun	5	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:35	11.43	11%	46.4°
2044-01-04 Mon	4	—	unknown	18:10–18:30 (marginal, 0.33 h)	71.1° 13:30	11.42	18%	49.8°
2044-01-05 Tue	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	27%	55.3°
2044-01-06 Wed	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.39	37%	62.4°
2044-01-07 Thu	1	—	unknown	—	71.1° 13:15	11.38	47%	70.8°
2044-01-08 Fri	1	—	unknown	—	71.1° 13:15	11.36	58%	80.1°
2044-01-09 Sat	1	—	unknown	—	71.1° 13:10	11.35	69%	89.9°
2044-01-10 Sun	1	—	unknown	—	71.1° 13:05	11.33	80%	100.0°
2044-01-11 Mon	0	—	unknown	—	71.1° 13:00	11.31	88%	109.9°
2044-01-12 Tue	0	—	unknown	—	71.1° 12:55	11.29	95%	119.1°
2044-01-13 Wed	0	—	unknown	—	71.1° 12:55	11.27	99%	126.9°
2044-01-14 Thu	0	—	unknown	—	71.1° 12:50	11.25	100%	132.3°
2044-01-15 Fri	0	—	unknown	—	71.1° 12:45	11.23	98%	134.5°
2044-01-16 Sat	0	—	unknown	—	71.1° 12:40	11.21	94%	133.0°
2044-01-17 Sun	0	—	unknown	—	71.1° 12:40	11.19	87%	128.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-12-19&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.