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 Vega: 01-13 (22), 01-12 (21), 01-11 (20), 01-14 (19), 01-15 (19) — by astronomy; check the weather when the night is within four days.

2040-12-18astronomy score per night — click a bar for that night2041-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-18 Tue	15	—	unknown	18:35–18:55 (good, 0.33 h)	87.1° 13:10	11.51	100%	114.3°
2040-12-19 Wed	15	—	unknown	18:35–18:50 (good, 0.25 h)	87.1° 13:05	11.51	98%	114.3°
2040-12-20 Thu	15	—	unknown	18:35–18:50 (good, 0.25 h)	87.1° 13:00	11.51	94%	113.1°
2040-12-21 Fri	16	—	unknown	18:35–18:55 (good, 0.33 h)	87.1° 12:55	11.51	89%	111.0°
2040-12-22 Sat	14	—	unknown	18:35–18:50 (good, 0.25 h)	87.1° 12:55	11.51	83%	107.9°
2040-12-23 Sun	12	—	unknown	18:40–18:50 (good, 0.17 h)	87.1° 12:50	11.5	75%	104.2°
2040-12-24 Mon	11	—	unknown	18:40–18:45 (good, 0.08 h)	87.1° 12:45	11.5	67%	99.8°
2040-12-25 Tue	10	—	unknown	18:05–19:10 (marginal, 1.08 h)	87.1° 12:40	11.5	58%	95.1°
2040-12-26 Wed	10	—	unknown	18:40–19:10 (marginal, 0.5 h)	87.1° 12:35	11.49	48%	90.1°
2040-12-27 Thu	9	—	unknown	18:40–19:05 (marginal, 0.42 h)	87.1° 12:35	11.49	38%	84.9°
2040-12-28 Fri	9	—	unknown	18:40–19:00 (marginal, 0.33 h)	87.1° 12:30	11.48	28%	79.8°
2040-12-29 Sat	8	—	unknown	18:40–18:55 (marginal, 0.25 h)	87.1° 12:25	11.47	19%	75.0°
2040-12-30 Sun	8	—	unknown	05:50–06:10 (marginal, 0.33 h)	87.1° 12:20	11.47	11%	70.8°
2040-12-31 Mon	9	—	unknown	05:50–06:10 (marginal, 0.33 h)	87.1° 12:20	11.46	5%	67.7°
2041-01-01 Tue	9	—	unknown	05:45–06:10 (marginal, 0.42 h)	87.1° 12:15	11.45	1%	65.8°
2041-01-02 Wed	10	—	unknown	05:40–06:45 (marginal, 1.08 h)	87.1° 12:10	11.44	0%	65.7°
2041-01-03 Thu	11	—	unknown	06:05–06:10 (good, 0.08 h)	87.1° 12:05	11.42	2%	67.4°
2041-01-04 Fri	12	—	unknown	06:05–06:10 (good, 0.08 h)	87.1° 12:00	11.41	7%	70.6°
2041-01-05 Sat	12	—	unknown	06:00–06:10 (good, 0.17 h)	87.1° 11:55	11.4	14%	75.1°
2041-01-06 Sun	13	—	unknown	05:55–06:10 (good, 0.25 h)	87.1° 11:50	11.38	24%	80.4°
2041-01-07 Mon	15	—	unknown	05:50–06:10 (good, 0.33 h)	87.1° 11:45	11.37	34%	86.1°
2041-01-08 Tue	16	—	unknown	05:50–06:10 (good, 0.33 h)	87.1° 11:40	11.35	45%	91.8°
2041-01-09 Wed	17	—	unknown	05:45–06:10 (good, 0.42 h)	87.1° 11:40	11.34	56%	97.3°
2041-01-10 Thu	18	—	unknown	05:40–06:10 (good, 0.5 h)	87.1° 11:35	11.32	66%	102.2°
2041-01-11 Fri	20	—	unknown	05:35–06:10 (good, 0.58 h)	87.1° 11:30	11.3	75%	106.6°
2041-01-12 Sat	21	—	unknown	05:30–06:10 (good, 0.67 h)	87.1° 11:25	11.28	83%	110.1°
2041-01-13 Sun	22	—	unknown	05:35–06:10 (good, 0.58 h)	87.1° 11:20	11.26	90%	112.6°
2041-01-14 Mon	19	—	unknown	05:35–06:10 (good, 0.58 h)	87.1° 11:20	11.24	95%	114.1°
2041-01-15 Tue	19	—	unknown	05:35–06:10 (good, 0.58 h)	87.1° 11:15	11.22	98%	114.4°
2041-01-16 Wed	19	—	unknown	05:30–06:10 (good, 0.67 h)	87.1° 11:10	11.2	100%	113.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-18&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.