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.

2027-07-11astronomy score per night — click a bar for that night2027-08-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-11 Sun	87	—	unknown	00:45–03:55 (good, 3.17 h)	89.7° 06:45	4.83	62%	151.4°
2027-07-12 Mon	88	—	unknown	00:45–03:55 (good, 3.17 h)	89.5° 06:40	4.87	72%	147.0°
2027-07-13 Tue	89	—	unknown	00:40–03:55 (good, 3.25 h)	89.6° 06:40	4.9	80%	139.5°
2027-07-14 Wed	91	—	unknown	00:40–04:00 (good, 3.33 h)	89.7° 06:35	4.95	88%	130.5°
2027-07-15 Thu	91	—	unknown	00:35–04:00 (good, 3.42 h)	89.7° 06:30	4.99	93%	120.6°
2027-07-16 Fri	76	—	unknown	00:40–04:00 (good, 3.33 h)	89.6° 06:25	5.03	97%	110.4°
2027-07-17 Sat	66	—	unknown	00:45–04:00 (good, 3.25 h)	89.5° 06:20	5.07	100%	100.0°
2027-07-18 Sun	58	—	unknown	01:05–04:05 (good, 3.0 h)	89.6° 06:20	5.12	100%	89.6°
2027-07-19 Mon	48	—	unknown	02:10–04:05 (good, 1.92 h)	89.7° 06:15	5.17	98%	79.2°
2027-07-20 Tue	41	—	unknown	03:20–04:05 (good, 0.75 h)	89.7° 06:10	5.21	95%	68.9°
2027-07-21 Wed	36	—	unknown	23:40–04:10 (marginal, 4.5 h)	89.6° 06:05	5.26	91%	58.7°
2027-07-22 Thu	34	—	unknown	23:35–04:10 (marginal, 4.58 h)	89.5° 06:05	5.31	84%	49.0°
2027-07-23 Fri	34	—	unknown	23:25–04:10 (marginal, 4.75 h)	89.6° 06:00	5.36	77%	40.1°
2027-07-24 Sat	39	—	unknown	23:20–04:15 (marginal, 4.92 h)	89.7° 05:55	5.41	68%	32.8°
2027-07-25 Sun	50	—	unknown	00:50–04:00 (good, 3.17 h)	89.7° 05:50	5.46	58%	28.6°
2027-07-26 Mon	69	—	unknown	23:45–04:15 (good, 4.5 h)	89.5° 05:45	5.51	48%	29.2°
2027-07-27 Tue	83	—	unknown	23:40–04:15 (good, 4.58 h)	89.6° 05:45	5.56	37%	34.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-11&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.