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: 06-15 (35), 06-14 (34), 06-13 (33), 06-12 (32), 06-16 (32) — by astronomy; check the weather when the night is within four days.

2027-05-21astronomy score per night — click a bar for that night2027-06-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-05-21 Fri	7	—	unknown	03:30–04:00 (marginal, 0.5 h)	89.6° 10:05	5.28	98%	125.4°
2027-05-22 Sat	7	—	unknown	03:25–03:55 (marginal, 0.5 h)	89.5° 10:05	5.23	94%	115.2°
2027-05-23 Sun	7	—	unknown	03:20–03:55 (marginal, 0.58 h)	89.6° 10:00	5.19	89%	104.9°
2027-05-24 Mon	7	—	unknown	03:20–03:55 (marginal, 0.58 h)	89.7° 09:55	5.14	82%	94.4°
2027-05-25 Tue	7	—	unknown	03:15–03:55 (marginal, 0.67 h)	89.7° 09:50	5.09	74%	84.0°
2027-05-26 Wed	7	—	unknown	03:10–03:50 (marginal, 0.67 h)	89.6° 09:45	5.05	66%	73.7°
2027-05-27 Thu	8	—	unknown	03:05–03:50 (marginal, 0.75 h)	89.5° 09:45	5.0	56%	63.4°
2027-05-28 Fri	10	—	unknown	03:00–03:50 (marginal, 0.83 h)	89.7° 09:40	4.96	47%	53.4°
2027-05-29 Sat	11	—	unknown	03:00–04:40 (marginal, 1.67 h)	89.7° 09:35	4.92	37%	44.0°
2027-05-30 Sun	12	—	unknown	03:40–03:45 (good, 0.08 h)	89.7° 09:30	4.88	27%	35.6°
2027-05-31 Mon	15	—	unknown	03:30–03:45 (good, 0.25 h)	89.5° 09:25	4.84	19%	29.8°
2027-06-01 Tue	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.6° 09:25	4.8	11%	28.7°
2027-06-02 Wed	20	—	unknown	03:15–03:45 (good, 0.5 h)	89.7° 09:20	4.77	5%	33.3°
2027-06-03 Thu	22	—	unknown	03:10–03:45 (good, 0.58 h)	89.7° 09:15	4.73	1%	42.0°
2027-06-04 Fri	23	—	unknown	03:10–03:45 (good, 0.58 h)	89.6° 09:10	4.7	0%	53.0°
2027-06-05 Sat	24	—	unknown	03:05–03:40 (good, 0.58 h)	89.5° 09:10	4.67	2%	65.3°
2027-06-06 Sun	25	—	unknown	03:00–03:40 (good, 0.67 h)	89.6° 09:05	4.64	6%	78.2°
2027-06-07 Mon	25	—	unknown	02:55–03:40 (good, 0.75 h)	89.7° 09:00	4.61	14%	91.2°
2027-06-08 Tue	27	—	unknown	02:50–03:40 (good, 0.83 h)	89.7° 08:55	4.59	23%	104.1°
2027-06-09 Wed	28	—	unknown	02:50–03:40 (good, 0.83 h)	89.6° 08:50	4.56	33%	116.5°
2027-06-10 Thu	30	—	unknown	02:45–03:40 (good, 0.92 h)	89.5° 08:50	4.54	44%	128.1°
2027-06-11 Fri	31	—	unknown	02:40–03:40 (good, 1.0 h)	89.7° 08:45	4.52	55%	138.5°
2027-06-12 Sat	32	—	unknown	02:35–03:40 (good, 1.08 h)	89.7° 08:40	4.5	66%	146.7°
2027-06-13 Sun	33	—	unknown	02:30–03:40 (good, 1.17 h)	89.7° 08:35	4.48	76%	151.2°
2027-06-14 Mon	34	—	unknown	02:35–03:40 (good, 1.08 h)	89.5° 08:30	4.47	84%	150.6°
2027-06-15 Tue	35	—	unknown	02:35–03:40 (good, 1.08 h)	89.6° 08:30	4.45	91%	145.4°
2027-06-16 Wed	32	—	unknown	02:30–03:40 (good, 1.17 h)	89.7° 08:25	4.44	96%	137.4°
2027-06-17 Thu	32	—	unknown	02:25–03:40 (good, 1.25 h)	89.7° 08:20	4.44	99%	128.1°
2027-06-18 Fri	32	—	unknown	02:25–03:40 (good, 1.25 h)	89.6° 08:15	4.43	100%	118.1°
2027-06-19 Sat	30	—	unknown	02:30–03:40 (good, 1.17 h)	89.5° 08:15	4.42	99%	107.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-21&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.