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: 07-30 (100), 07-31 (100), 08-01 (100), 08-02 (100), 08-03 (100) — by astronomy; check the weather when the night is within four days.

2027-07-28astronomy score per night — click a bar for that night2027-08-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-28 Wed	88	—	unknown	23:35–04:20 (good, 4.75 h)	89.7° 05:40	5.62	27%	43.8°
2027-07-29 Thu	95	—	unknown	23:30–04:20 (good, 4.83 h)	89.7° 05:35	5.67	17%	54.8°
2027-07-30 Fri	100	—	unknown	23:30–04:20 (good, 4.83 h)	89.6° 05:30	5.72	9%	67.1°
2027-07-31 Sat	100	—	unknown	23:25–04:25 (good, 5.0 h)	89.5° 05:25	5.78	3%	80.1°
2027-08-01 Sun	100	—	unknown	23:20–04:25 (good, 5.08 h)	89.6° 05:25	5.83	0%	93.5°
2027-08-02 Mon	100	—	unknown	23:15–04:25 (good, 5.17 h)	89.7° 05:20	5.89	0%	106.8°
2027-08-03 Tue	100	—	unknown	23:10–04:30 (good, 5.33 h)	89.7° 05:15	5.94	4%	119.8°
2027-08-04 Wed	100	—	unknown	23:10–04:30 (good, 5.33 h)	89.6° 05:10	6.0	9%	131.8°
2027-08-05 Thu	100	—	unknown	23:05–04:30 (good, 5.42 h)	89.5° 05:10	6.06	17%	142.2°
2027-08-06 Fri	100	—	unknown	23:00–04:35 (good, 5.58 h)	89.6° 05:05	6.11	26%	149.4°
2027-08-07 Sat	100	—	unknown	22:55–04:35 (good, 5.67 h)	89.7° 05:00	6.17	37%	151.8°
2027-08-08 Sun	100	—	unknown	22:55–04:35 (good, 5.67 h)	89.7° 04:55	6.23	47%	148.6°
2027-08-09 Mon	100	—	unknown	22:55–04:40 (good, 5.75 h)	89.5° 04:50	6.28	57%	141.7°
2027-08-10 Tue	100	—	unknown	22:50–04:40 (good, 5.83 h)	89.5° 04:50	6.34	67%	132.8°
2027-08-11 Wed	100	—	unknown	22:50–04:40 (good, 5.83 h)	89.7° 04:45	6.4	76%	123.1°
2027-08-12 Thu	100	—	unknown	22:50–04:40 (good, 5.83 h)	89.7° 04:40	6.46	84%	113.0°
2027-08-13 Fri	100	—	unknown	22:55–04:45 (good, 5.83 h)	89.6° 04:35	6.51	90%	102.6°
2027-08-14 Sat	100	—	unknown	23:00–04:45 (good, 5.75 h)	89.5° 04:30	6.57	95%	92.2°
2027-08-15 Sun	76	—	unknown	00:00–04:45 (good, 4.75 h)	89.6° 04:30	6.63	98%	81.8°
2027-08-16 Mon	68	—	unknown	01:35–04:50 (good, 3.25 h)	89.7° 04:25	6.69	100%	71.4°
2027-08-17 Tue	55	—	unknown	22:05–04:50 (marginal, 6.75 h)	89.7° 04:20	6.74	100%	61.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-28&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.