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 Andromeda Galaxy: 06-18 (41), 06-17 (39), 06-16 (37), 06-15 (35), 06-14 (29) — by astronomy; check the weather when the night is within four days.

2031-05-20astronomy score per night — click a bar for that night2031-06-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-20 Tue	7	—	unknown	04:05–04:45 (marginal, 0.67 h)	89.7° 10:10	5.33	0%	42.1°
2031-05-21 Wed	8	—	unknown	04:05–04:45 (marginal, 0.67 h)	89.6° 10:05	5.28	0%	50.7°
2031-05-22 Thu	9	—	unknown	04:00–04:45 (marginal, 0.75 h)	89.5° 10:05	5.23	2%	60.1°
2031-05-23 Fri	10	—	unknown	03:20–04:45 (marginal, 1.42 h)	89.7° 10:00	5.18	6%	70.0°
2031-05-24 Sat	10	—	unknown	03:50–03:55 (good, 0.08 h)	89.7° 09:55	5.14	12%	80.1°
2031-05-25 Sun	11	—	unknown	03:45–03:55 (good, 0.17 h)	89.7° 09:50	5.09	18%	90.2°
2031-05-26 Mon	12	—	unknown	03:45–03:50 (good, 0.08 h)	89.6° 09:45	5.05	26%	100.4°
2031-05-27 Tue	13	—	unknown	03:40–03:50 (good, 0.17 h)	89.6° 09:45	5.0	35%	110.6°
2031-05-28 Wed	15	—	unknown	03:35–03:50 (good, 0.25 h)	89.7° 09:40	4.96	45%	120.5°
2031-05-29 Thu	16	—	unknown	03:30–03:50 (good, 0.33 h)	89.7° 09:35	4.92	55%	130.2°
2031-05-30 Fri	15	—	unknown	03:30–03:45 (good, 0.25 h)	89.7° 09:30	4.88	65%	139.0°
2031-05-31 Sat	17	—	unknown	03:25–03:45 (good, 0.33 h)	89.5° 09:25	4.84	74%	146.0°
2031-06-01 Sun	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.6° 09:25	4.8	83%	149.4°
2031-06-02 Mon	17	—	unknown	03:25–03:45 (good, 0.33 h)	89.7° 09:20	4.77	91%	147.4°
2031-06-03 Tue	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.7° 09:15	4.73	96%	140.5°
2031-06-04 Wed	19	—	unknown	03:20–03:45 (good, 0.42 h)	89.6° 09:10	4.7	100%	130.4°
2031-06-05 Thu	18	—	unknown	03:15–03:40 (good, 0.42 h)	89.5° 09:10	4.67	100%	118.6°
2031-06-06 Fri	17	—	unknown	03:20–03:40 (good, 0.33 h)	89.7° 09:05	4.64	97%	106.0°
2031-06-07 Sat	15	—	unknown	03:25–03:40 (good, 0.25 h)	89.7° 09:00	4.61	91%	93.2°
2031-06-08 Sun	14	—	unknown	02:20–03:40 (marginal, 1.33 h)	89.7° 08:55	4.59	83%	80.4°
2031-06-09 Mon	14	—	unknown	02:15–03:40 (marginal, 1.42 h)	89.6° 08:50	4.56	74%	68.1°
2031-06-10 Tue	15	—	unknown	02:10–03:40 (marginal, 1.5 h)	89.5° 08:50	4.54	63%	56.6°
2031-06-11 Wed	18	—	unknown	03:10–03:40 (good, 0.5 h)	89.7° 08:45	4.52	52%	46.2°
2031-06-12 Thu	20	—	unknown	03:00–03:40 (good, 0.67 h)	89.7° 08:40	4.5	41%	37.6°
2031-06-13 Fri	25	—	unknown	02:45–03:40 (good, 0.92 h)	89.7° 08:35	4.48	31%	32.1°
2031-06-14 Sat	29	—	unknown	02:30–03:40 (good, 1.17 h)	89.5° 08:30	4.47	22%	30.7°
2031-06-15 Sun	35	—	unknown	02:25–03:40 (good, 1.25 h)	89.6° 08:30	4.46	14%	33.8°
2031-06-16 Mon	37	—	unknown	02:20–03:40 (good, 1.33 h)	89.7° 08:25	4.44	8%	40.2°
2031-06-17 Tue	39	—	unknown	02:15–03:40 (good, 1.42 h)	89.7° 08:20	4.44	4%	48.4°
2031-06-18 Wed	41	—	unknown	02:15–03:40 (good, 1.42 h)	89.6° 08:15	4.43	1%	57.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-20&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.