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: 01-17 (93), 01-18 (86), 02-02 (82), 02-01 (81), 01-31 (80) — by astronomy; check the weather when the night is within four days.

2040-01-17astronomy score per night — click a bar for that night2040-02-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-17 Tue	93	—	unknown	19:00–23:30 (good, 4.5 h)	89.8° 17:20	11.19	19%	53.1°
2040-01-18 Wed	86	—	unknown	19:00–23:25 (good, 4.42 h)	89.8° 17:15	11.17	28%	44.9°
2040-01-19 Thu	71	—	unknown	19:00–23:05 (good, 4.08 h)	89.7° 17:10	11.14	38%	39.3°
2040-01-20 Fri	54	—	unknown	19:00–22:45 (good, 3.75 h)	89.5° 17:05	11.12	48%	36.9°
2040-01-21 Sat	41	—	unknown	19:25–19:55 (good, 0.5 h)	89.7° 17:05	11.09	58%	38.1°
2040-01-22 Sun	33	—	unknown	19:05–23:30 (marginal, 4.42 h)	89.8° 17:00	11.07	68%	42.3°
2040-01-23 Mon	29	—	unknown	19:05–23:15 (marginal, 4.17 h)	89.8° 16:55	11.04	76%	48.7°
2040-01-24 Tue	28	—	unknown	19:05–23:05 (marginal, 4.0 h)	89.6° 16:50	11.01	84%	56.4°
2040-01-25 Wed	30	—	unknown	19:05–23:00 (marginal, 3.92 h)	89.5° 16:50	10.98	90%	65.0°
2040-01-26 Thu	35	—	unknown	19:05–19:25 (good, 0.33 h)	89.7° 16:45	10.96	95%	74.1°
2040-01-27 Fri	41	—	unknown	19:10–20:20 (good, 1.17 h)	89.8° 16:40	10.93	98%	83.5°
2040-01-28 Sat	50	—	unknown	19:10–21:15 (good, 2.08 h)	89.7° 16:35	10.9	100%	93.1°
2040-01-29 Sun	60	—	unknown	19:10–22:10 (good, 3.0 h)	89.6° 16:30	10.87	100%	102.8°
2040-01-30 Mon	69	—	unknown	19:10–22:20 (good, 3.17 h)	89.6° 16:30	10.83	97%	112.3°
2040-01-31 Tue	80	—	unknown	19:15–22:20 (good, 3.08 h)	89.8° 16:25	10.8	93%	121.6°
2040-02-01 Wed	81	—	unknown	19:15–22:20 (good, 3.08 h)	89.8° 16:20	10.77	88%	130.0°
2040-02-02 Thu	82	—	unknown	19:15–22:20 (good, 3.08 h)	89.7° 16:15	10.74	80%	137.2°
2040-02-03 Fri	80	—	unknown	19:15–22:20 (good, 3.08 h)	89.5° 16:10	10.7	71%	142.0°
2040-02-04 Sat	78	—	unknown	19:15–22:15 (good, 3.0 h)	89.7° 16:10	10.67	61%	143.2°
2040-02-05 Sun	74	—	unknown	19:20–22:15 (good, 2.92 h)	89.8° 16:05	10.64	50%	140.4°
2040-02-06 Mon	72	—	unknown	19:20–22:10 (good, 2.83 h)	89.8° 16:00	10.6	39%	134.0°
2040-02-07 Tue	70	—	unknown	19:20–22:05 (good, 2.75 h)	89.6° 15:55	10.56	28%	125.1°
2040-02-08 Wed	68	—	unknown	19:20–22:00 (good, 2.67 h)	89.5° 15:55	10.53	18%	114.6°
2040-02-09 Thu	64	—	unknown	19:25–22:00 (good, 2.58 h)	89.7° 15:50	10.49	10%	103.1°
2040-02-10 Fri	62	—	unknown	19:25–21:55 (good, 2.5 h)	89.8° 15:45	10.45	4%	91.3°
2040-02-11 Sat	60	—	unknown	19:25–21:50 (good, 2.42 h)	89.7° 15:40	10.42	1%	79.4°
2040-02-12 Sun	58	—	unknown	19:25–21:45 (good, 2.33 h)	89.6° 15:35	10.38	0%	67.9°
2040-02-13 Mon	57	—	unknown	19:25–21:40 (good, 2.25 h)	89.6° 15:35	10.34	3%	57.2°
2040-02-14 Tue	51	—	unknown	19:30–21:40 (good, 2.17 h)	89.7° 15:30	10.3	7%	48.0°
2040-02-15 Wed	46	—	unknown	19:30–21:35 (good, 2.08 h)	89.8° 15:25	10.26	14%	41.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-17&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.