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: 09-23 (100), 09-24 (100), 09-25 (100), 09-26 (100), 09-27 (100) — by astronomy; check the weather when the night is within four days.

2027-09-20astronomy score per night — click a bar for that night2027-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-20 Mon	85	—	unknown	21:00–23:50 (good, 2.83 h)	89.6° 02:05	8.62	76%	38.8°
2027-09-21 Tue	90	—	unknown	20:55–03:15 (good, 6.33 h)	89.5° 02:05	8.67	66%	48.4°
2027-09-22 Wed	97	—	unknown	20:55–05:40 (good, 8.75 h)	89.7° 02:00	8.72	56%	59.3°
2027-09-23 Thu	100	—	unknown	20:55–05:40 (good, 8.75 h)	89.7° 01:55	8.77	44%	71.2°
2027-09-24 Fri	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.7° 01:50	8.82	33%	83.5°
2027-09-25 Sat	100	—	unknown	20:50–05:40 (good, 8.83 h)	89.5° 01:45	8.87	23%	96.2°
2027-09-26 Sun	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.6° 01:45	8.92	14%	108.9°
2027-09-27 Mon	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.7° 01:40	8.97	7%	121.4°
2027-09-28 Tue	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.7° 01:35	9.02	2%	133.2°
2027-09-29 Wed	100	—	unknown	20:40–05:45 (good, 9.08 h)	89.6° 01:30	9.07	0%	143.3°
2027-09-30 Thu	100	—	unknown	20:40–05:45 (good, 9.08 h)	89.5° 01:30	9.12	1%	150.1°
2027-10-01 Fri	100	—	unknown	20:40–05:50 (good, 9.17 h)	89.6° 01:25	9.17	4%	151.3°
2027-10-02 Sat	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.7° 01:20	9.22	10%	146.9°
2027-10-03 Sun	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.7° 01:15	9.26	17%	138.9°
2027-10-04 Mon	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.6° 01:10	9.31	26%	129.3°
2027-10-05 Tue	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.5° 01:10	9.36	35%	119.1°
2027-10-06 Wed	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.7° 01:05	9.4	44%	108.7°
2027-10-07 Thu	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.7° 01:00	9.45	54%	98.2°
2027-10-08 Fri	100	—	unknown	20:25–05:55 (good, 9.5 h)	89.7° 00:55	9.5	63%	87.8°
2027-10-09 Sat	100	—	unknown	20:25–05:55 (good, 9.5 h)	89.5° 00:50	9.54	72%	77.4°
2027-10-10 Sun	100	—	unknown	20:45–06:00 (good, 9.25 h)	89.6° 00:50	9.59	80%	67.1°
2027-10-11 Mon	95	—	unknown	00:55–06:00 (good, 5.08 h)	89.7° 00:45	9.63	87%	57.0°
2027-10-12 Tue	87	—	unknown	05:10–06:00 (good, 0.83 h)	89.7° 00:40	9.68	93%	47.4°
2027-10-13 Wed	51	—	unknown	20:20–06:00 (marginal, 9.67 h)	89.6° 00:35	9.72	97%	38.6°
2027-10-14 Thu	37	—	unknown	02:05–06:05 (marginal, 4.0 h)	89.5° 00:35	9.77	99%	31.7°
2027-10-15 Fri	33	—	unknown	20:15–22:55 (marginal, 2.67 h)	89.6° 00:30	9.81	100%	28.5°
2027-10-16 Sat	37	—	unknown	20:15–23:45 (marginal, 3.5 h)	89.7° 00:25	9.85	98%	30.4°
2027-10-17 Sun	53	—	unknown	20:10–04:00 (marginal, 7.83 h)	89.7° 00:20	9.9	94%	36.8°
2027-10-18 Mon	62	—	unknown	20:10–22:05 (good, 1.92 h)	89.6° 00:15	9.94	88%	46.1°
2027-10-19 Tue	95	—	unknown	20:10–01:00 (good, 4.83 h)	89.5° 00:15	9.98	80%	56.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-20&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.