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: 12-15 (33), 12-16 (33), 12-17 (32), 12-13 (30), 12-14 (30) — by astronomy; check the weather when the night is within four days.

2027-12-05astronomy score per night — click a bar for that night2028-01-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-05 Sun	28	—	unknown	18:35–20:05 (good, 1.5 h)	71.1° 15:25	11.39	47%	48.2°
2027-12-06 Mon	23	—	unknown	18:35–19:10 (good, 0.58 h)	71.1° 15:25	11.4	57%	54.4°
2027-12-07 Tue	20	—	unknown	18:00–20:45 (marginal, 2.75 h)	71.1° 15:20	11.42	66%	62.0°
2027-12-08 Wed	19	—	unknown	18:35–20:40 (marginal, 2.08 h)	71.1° 15:15	11.43	75%	70.6°
2027-12-09 Thu	19	—	unknown	18:00–20:35 (marginal, 2.58 h)	71.1° 15:10	11.44	83%	79.9°
2027-12-10 Fri	21	—	unknown	18:35–19:00 (good, 0.42 h)	71.1° 15:05	11.45	90%	89.8°
2027-12-11 Sat	23	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 15:05	11.46	96%	99.9°
2027-12-12 Sun	26	—	unknown	18:35–19:45 (good, 1.17 h)	71.1° 15:00	11.47	99%	110.1°
2027-12-13 Mon	30	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:55	11.48	100%	119.9°
2027-12-14 Tue	30	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:50	11.48	98%	128.5°
2027-12-15 Wed	33	—	unknown	18:35–19:45 (good, 1.17 h)	71.1° 14:45	11.49	93%	135.1°
2027-12-16 Thu	33	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:45	11.5	86%	138.3°
2027-12-17 Fri	32	—	unknown	18:35–19:45 (good, 1.17 h)	71.1° 14:40	11.5	77%	137.5°
2027-12-18 Sat	30	—	unknown	18:35–19:40 (good, 1.08 h)	71.1° 14:35	11.5	66%	133.0°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-05&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.