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: 05-07 (2), 05-08 (2), 04-27 (1), 04-28 (1), 04-29 (1) — by astronomy; check the weather when the night is within four days.

2031-04-09astronomy score per night — click a bar for that night2031-05-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-09 Wed	0	—	unknown	—	89.7° 12:55	7.65	94%	142.1°
2031-04-10 Thu	0	—	unknown	—	89.6° 12:50	7.59	87%	132.8°
2031-04-11 Fri	0	—	unknown	—	89.5° 12:50	7.53	78%	121.8°
2031-04-12 Sat	0	—	unknown	—	89.7° 12:45	7.48	68%	110.1°
2031-04-13 Sun	0	—	unknown	—	89.7° 12:40	7.42	57%	97.9°
2031-04-14 Mon	0	—	unknown	—	89.7° 12:35	7.36	46%	85.8°
2031-04-15 Tue	0	—	unknown	—	89.5° 12:30	7.31	34%	73.9°
2031-04-16 Wed	0	—	unknown	—	89.6° 12:30	7.25	24%	62.3°
2031-04-17 Thu	0	—	unknown	—	89.7° 12:25	7.19	16%	51.5°
2031-04-18 Fri	0	—	unknown	—	89.7° 12:20	7.13	8%	41.9°
2031-04-19 Sat	0	—	unknown	—	89.6° 12:15	7.07	4%	34.5°
2031-04-20 Sun	0	—	unknown	—	89.5° 12:10	7.02	1%	30.8°
2031-04-21 Mon	0	—	unknown	—	89.6° 12:10	6.96	0%	31.8°
2031-04-22 Tue	0	—	unknown	—	89.7° 12:05	6.9	2%	36.9°
2031-04-23 Wed	0	—	unknown	—	89.7° 12:00	6.84	5%	44.5°
2031-04-24 Thu	0	—	unknown	—	89.5° 11:55	6.78	10%	53.5°
2031-04-25 Fri	0	—	unknown	—	89.7° 11:50	6.72	16%	63.1°
2031-04-26 Sat	0	—	unknown	—	89.7° 11:45	6.67	24%	73.0°
2031-04-27 Sun	1	—	unknown	—	89.7° 11:40	6.61	32%	83.1°
2031-04-28 Mon	1	—	unknown	—	89.5° 11:35	6.55	42%	93.3°
2031-04-29 Tue	1	—	unknown	—	89.6° 11:35	6.49	51%	103.5°
2031-04-30 Wed	1	—	unknown	—	89.7° 11:30	6.43	61%	113.8°
2031-05-01 Thu	1	—	unknown	—	89.7° 11:25	6.38	70%	123.9°
2031-05-02 Fri	1	—	unknown	—	89.6° 11:20	6.32	79%	133.5°
2031-05-03 Sat	1	—	unknown	—	89.5° 11:15	6.26	87%	142.0°
2031-05-04 Sun	1	—	unknown	—	89.6° 11:15	6.2	94%	147.9°
2031-05-05 Mon	1	—	unknown	—	89.7° 11:10	6.14	98%	149.2°
2031-05-06 Tue	1	—	unknown	—	89.7° 11:05	6.09	100%	144.9°
2031-05-07 Wed	2	—	unknown	—	89.6° 11:00	6.03	99%	136.4°
2031-05-08 Thu	2	—	unknown	—	89.5° 11:00	5.97	96%	125.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-09&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.