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.

2027-12-19astronomy score per night — click a bar for that night2028-01-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-19 Sun	29	—	unknown	18:35–19:40 (good, 1.08 h)	71.1° 14:30	11.51	55%	125.8°
2027-12-20 Mon	27	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 14:30	11.51	44%	117.1°
2027-12-21 Tue	25	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:25	11.51	33%	107.6°
2027-12-22 Wed	24	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:20	11.51	24%	97.8°
2027-12-23 Thu	22	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.51	15%	87.9°
2027-12-24 Fri	20	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:10	11.5	8%	78.3°
2027-12-25 Sat	19	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	4%	69.0°
2027-12-26 Sun	18	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	1%	60.5°
2027-12-27 Mon	17	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	0%	52.9°
2027-12-28 Tue	15	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.49	1%	46.9°
2027-12-29 Wed	13	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:50	11.48	4%	42.8°
2027-12-30 Thu	10	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:50	11.47	9%	41.4°
2027-12-31 Fri	8	—	unknown	18:10–19:20 (marginal, 1.17 h)	71.1° 13:45	11.46	15%	42.7°
2028-01-01 Sat	6	—	unknown	18:45–19:15 (marginal, 0.5 h)	71.1° 13:40	11.45	22%	46.5°
2028-01-02 Sun	5	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	30%	52.2°
2028-01-03 Mon	4	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.43	39%	59.3°
2028-01-04 Tue	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:30	11.42	49%	67.4°
2028-01-05 Wed	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:25	11.41	58%	76.3°
2028-01-06 Thu	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.4	68%	85.7°
2028-01-07 Fri	1	—	unknown	—	71.1° 13:15	11.38	78%	95.6°
2028-01-08 Sat	1	—	unknown	—	71.1° 13:15	11.37	86%	105.6°
2028-01-09 Sun	1	—	unknown	—	71.1° 13:10	11.35	93%	115.6°
2028-01-10 Mon	1	—	unknown	—	71.1° 13:05	11.33	98%	124.9°
2028-01-11 Tue	1	—	unknown	—	71.1° 13:00	11.31	100%	132.6°
2028-01-12 Wed	0	—	unknown	—	71.1° 12:55	11.3	99%	137.6°
2028-01-13 Thu	0	—	unknown	—	71.1° 12:55	11.28	95%	138.4°
2028-01-14 Fri	0	—	unknown	—	71.1° 12:50	11.26	89%	135.0°
2028-01-15 Sat	0	—	unknown	—	71.1° 12:45	11.24	80%	128.2°
2028-01-16 Sun	0	—	unknown	—	71.1° 12:40	11.21	70%	119.6°
2028-01-17 Mon	0	—	unknown	—	71.1° 12:35	11.19	60%	110.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-19&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.