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: 11-27 (64), 11-28 (62), 11-29 (60), 11-30 (58), 12-01 (52) — by astronomy; check the weather when the night is within four days.

2027-11-27astronomy score per night — click a bar for that night2027-12-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-11-27 Sat	64	—	unknown	18:35–21:05 (good, 2.5 h)	71.1° 16:00	11.25	0%	75.6°
2027-11-28 Sun	62	—	unknown	18:35–21:00 (good, 2.42 h)	71.1° 15:55	11.27	1%	66.4°
2027-11-29 Mon	60	—	unknown	18:35–20:55 (good, 2.33 h)	71.1° 15:50	11.29	3%	58.1°
2027-11-30 Tue	58	—	unknown	18:35–20:50 (good, 2.25 h)	71.1° 15:45	11.31	8%	50.9°
2027-12-01 Wed	52	—	unknown	18:35–20:50 (good, 2.25 h)	71.1° 15:40	11.33	14%	45.5°
2027-12-02 Thu	46	—	unknown	18:35–20:45 (good, 2.17 h)	71.1° 15:40	11.34	21%	42.2°
2027-12-03 Fri	39	—	unknown	18:35–20:30 (good, 1.92 h)	71.1° 15:35	11.36	29%	41.6°
2027-12-04 Sat	33	—	unknown	18:35–20:20 (good, 1.75 h)	71.1° 15:30	11.38	38%	43.7°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-11-27&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.