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: 08-26 (100), 08-27 (100), 08-28 (100), 08-29 (100), 08-30 (100) — by astronomy; check the weather when the night is within four days.

2027-08-18astronomy score per night — click a bar for that night2027-09-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-18 Wed	42	—	unknown	22:05–04:50 (marginal, 6.75 h)	89.6° 04:15	6.8	98%	51.4°
2027-08-19 Thu	36	—	unknown	22:00–04:55 (marginal, 6.92 h)	89.5° 04:15	6.86	94%	42.2°
2027-08-20 Fri	37	—	unknown	22:00–04:55 (marginal, 6.92 h)	89.6° 04:10	6.92	88%	34.4°
2027-08-21 Sat	43	—	unknown	22:00–04:55 (marginal, 6.92 h)	89.7° 04:05	6.97	81%	29.3°
2027-08-22 Sun	70	—	unknown	21:55–22:15 (good, 0.33 h)	89.7° 04:00	7.03	72%	28.6°
2027-08-23 Mon	82	—	unknown	21:55–02:30 (good, 4.58 h)	89.5° 03:55	7.09	62%	32.8°
2027-08-24 Tue	86	—	unknown	21:50–05:00 (good, 7.17 h)	89.5° 03:55	7.15	52%	40.8°
2027-08-25 Wed	92	—	unknown	21:50–05:00 (good, 7.17 h)	89.7° 03:50	7.2	41%	51.0°
2027-08-26 Thu	100	—	unknown	21:50–05:05 (good, 7.25 h)	89.7° 03:45	7.26	30%	62.5°
2027-08-27 Fri	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.6° 03:40	7.32	20%	74.8°
2027-08-28 Sat	100	—	unknown	21:45–05:05 (good, 7.33 h)	89.5° 03:35	7.37	11%	87.7°
2027-08-29 Sun	100	—	unknown	21:40–05:10 (good, 7.5 h)	89.6° 03:35	7.43	5%	100.9°
2027-08-30 Mon	100	—	unknown	21:40–05:10 (good, 7.5 h)	89.7° 03:30	7.49	1%	114.0°
2027-08-31 Tue	100	—	unknown	21:40–05:10 (good, 7.5 h)	89.7° 03:25	7.54	0%	126.5°
2027-09-01 Wed	100	—	unknown	21:35–05:10 (good, 7.58 h)	89.6° 03:20	7.6	2%	137.9°
2027-09-02 Thu	100	—	unknown	21:35–05:15 (good, 7.67 h)	89.5° 03:20	7.65	7%	146.9°
2027-09-03 Fri	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.6° 03:15	7.71	14%	151.5°
2027-09-04 Sat	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.7° 03:10	7.76	22%	150.2°
2027-09-05 Sun	100	—	unknown	21:30–05:15 (good, 7.75 h)	89.7° 03:05	7.82	32%	144.2°
2027-09-06 Mon	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.6° 03:00	7.87	42%	135.6°
2027-09-07 Tue	100	—	unknown	21:25–05:20 (good, 7.92 h)	89.5° 03:00	7.93	52%	125.9°
2027-09-08 Wed	100	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:55	7.98	61%	115.8°
2027-09-09 Thu	100	—	unknown	21:20–05:20 (good, 8.0 h)	89.7° 02:50	8.04	70%	105.5°
2027-09-10 Fri	100	—	unknown	21:20–05:25 (good, 8.08 h)	89.6° 02:45	8.09	79%	95.1°
2027-09-11 Sat	100	—	unknown	21:15–05:25 (good, 8.17 h)	89.5° 02:40	8.15	86%	84.7°
2027-09-12 Sun	100	—	unknown	22:40–05:25 (good, 6.75 h)	89.6° 02:40	8.2	92%	74.3°
2027-09-13 Mon	99	—	unknown	02:00–05:25 (good, 3.42 h)	89.7° 02:35	8.25	96%	64.0°
2027-09-14 Tue	63	—	unknown	04:45–05:30 (good, 0.75 h)	89.7° 02:30	8.31	99%	54.0°
2027-09-15 Wed	51	—	unknown	21:10–05:30 (marginal, 8.33 h)	89.6° 02:25	8.36	100%	44.6°
2027-09-16 Thu	35	—	unknown	21:05–05:30 (marginal, 8.42 h)	89.5° 02:25	8.41	99%	36.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-18&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.