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: 12-08 (34), 12-09 (28), 12-10 (24), 12-21 (24), 12-17 (23) — by astronomy; check the weather when the night is within four days.

2040-12-08astronomy score per night — click a bar for that night2041-01-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-08 Sat	34	—	unknown	18:35–20:10 (good, 1.58 h)	71.1° 15:10	11.44	27%	48.6°
2040-12-09 Sun	28	—	unknown	18:35–20:00 (good, 1.42 h)	71.1° 15:10	11.45	38%	52.9°
2040-12-10 Mon	24	—	unknown	18:35–19:45 (good, 1.17 h)	71.1° 15:05	11.46	49%	59.4°
2040-12-11 Tue	21	—	unknown	18:35–19:20 (good, 0.75 h)	71.1° 15:00	11.47	60%	67.2°
2040-12-12 Wed	19	—	unknown	18:35–18:55 (good, 0.33 h)	71.1° 14:55	11.48	71%	75.7°
2040-12-13 Thu	18	—	unknown	18:35–18:55 (good, 0.33 h)	71.1° 14:50	11.48	80%	84.5°
2040-12-14 Fri	19	—	unknown	18:35–19:10 (good, 0.58 h)	71.1° 14:50	11.49	88%	93.4°
2040-12-15 Sat	20	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:45	11.49	94%	102.0°
2040-12-16 Sun	22	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:40	11.5	98%	110.1°
2040-12-17 Mon	23	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:35	11.5	100%	117.5°
2040-12-18 Tue	23	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:35	11.51	100%	123.9°
2040-12-19 Wed	23	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:30	11.51	98%	128.8°
2040-12-20 Thu	23	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:25	11.51	94%	131.9°
2040-12-21 Fri	24	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:20	11.51	89%	132.8°
2040-12-22 Sat	23	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:15	11.51	83%	131.5°
2040-12-23 Sun	21	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.5	75%	128.2°
2040-12-24 Mon	20	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	67%	123.1°
2040-12-25 Tue	19	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	58%	116.8°
2040-12-26 Wed	17	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	48%	109.4°
2040-12-27 Thu	15	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 13:55	11.49	38%	101.2°
2040-12-28 Fri	14	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.48	28%	92.5°
2040-12-29 Sat	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:50	11.47	19%	83.5°
2040-12-30 Sun	10	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:45	11.47	11%	74.3°
2040-12-31 Mon	8	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:40	11.46	5%	65.3°
2041-01-01 Tue	7	—	unknown	18:10–19:10 (marginal, 1.0 h)	71.1° 13:40	11.45	1%	57.3°
2041-01-02 Wed	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:35	11.44	0%	51.0°
2041-01-03 Thu	5	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.42	2%	47.5°
2041-01-04 Fri	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	7%	47.6°
2041-01-05 Sat	3	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:20	11.4	14%	51.1°
2041-01-06 Sun	1	—	unknown	—	71.1° 13:20	11.38	24%	57.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-08&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.