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: 07-16 (100), 07-17 (100), 07-18 (100), 07-19 (100), 07-20 (100) — by astronomy; check the weather when the night is within four days.

2040-07-03astronomy score per night — click a bar for that night2040-08-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-03 Tue	59	—	unknown	01:10–03:45 (good, 2.58 h)	89.8° 07:15	4.6	25%	37.8°
2040-07-04 Wed	65	—	unknown	01:05–03:45 (good, 2.67 h)	89.7° 07:10	4.63	17%	42.4°
2040-07-05 Thu	72	—	unknown	01:05–03:50 (good, 2.75 h)	89.6° 07:05	4.66	10%	49.2°
2040-07-06 Fri	77	—	unknown	01:00–03:50 (good, 2.83 h)	89.6° 07:05	4.69	5%	57.3°
2040-07-07 Sat	79	—	unknown	00:55–03:50 (good, 2.92 h)	89.7° 07:00	4.72	2%	66.1°
2040-07-08 Sun	80	—	unknown	00:50–03:50 (good, 3.0 h)	89.8° 06:55	4.75	0%	75.4°
2040-07-09 Mon	85	—	unknown	00:45–03:55 (good, 3.17 h)	89.7° 06:50	4.79	0%	84.8°
2040-07-10 Tue	87	—	unknown	00:45–03:55 (good, 3.17 h)	89.5° 06:45	4.82	2%	94.3°
2040-07-11 Wed	89	—	unknown	00:40–03:55 (good, 3.25 h)	89.6° 06:45	4.86	6%	103.8°
2040-07-12 Thu	91	—	unknown	00:35–03:55 (good, 3.33 h)	89.8° 06:40	4.9	11%	113.2°
2040-07-13 Fri	94	—	unknown	00:30–04:00 (good, 3.5 h)	89.8° 06:35	4.94	18%	122.2°
2040-07-14 Sat	97	—	unknown	00:30–04:00 (good, 3.5 h)	89.6° 06:30	4.98	26%	130.4°
2040-07-15 Sun	99	—	unknown	00:25–04:00 (good, 3.58 h)	89.5° 06:30	5.02	35%	137.5°
2040-07-16 Mon	100	—	unknown	00:25–04:00 (good, 3.58 h)	89.7° 06:25	5.07	45%	142.3°
2040-07-17 Tue	100	—	unknown	00:20–04:05 (good, 3.75 h)	89.8° 06:20	5.11	56%	143.8°
2040-07-18 Wed	100	—	unknown	00:20–04:05 (good, 3.75 h)	89.7° 06:15	5.16	66%	141.2°
2040-07-19 Thu	100	—	unknown	00:15–04:05 (good, 3.83 h)	89.6° 06:10	5.21	77%	134.8°
2040-07-20 Fri	100	—	unknown	00:15–04:10 (good, 3.92 h)	89.6° 06:10	5.25	86%	125.8°
2040-07-21 Sat	100	—	unknown	00:15–04:10 (good, 3.92 h)	89.7° 06:05	5.3	93%	115.0°
2040-07-22 Sun	80	—	unknown	00:20–04:10 (good, 3.83 h)	89.8° 06:00	5.35	98%	103.2°
2040-07-23 Mon	68	—	unknown	00:25–04:10 (good, 3.75 h)	89.7° 05:55	5.4	100%	91.0°
2040-07-24 Tue	56	—	unknown	01:35–04:15 (good, 2.67 h)	89.5° 05:50	5.45	99%	78.7°
2040-07-25 Wed	47	—	unknown	02:50–04:15 (good, 1.42 h)	89.6° 05:50	5.5	95%	66.9°
2040-07-26 Thu	43	—	unknown	23:10–04:15 (marginal, 5.08 h)	89.8° 05:45	5.56	88%	56.0°
2040-07-27 Fri	44	—	unknown	23:05–04:20 (marginal, 5.25 h)	89.8° 05:40	5.61	80%	46.7°
2040-07-28 Sat	55	—	unknown	02:40–03:00 (good, 0.33 h)	89.6° 05:35	5.66	70%	39.8°
2040-07-29 Sun	76	—	unknown	23:30–04:20 (good, 4.83 h)	89.5° 05:35	5.72	60%	36.3°
2040-07-30 Mon	84	—	unknown	23:25–04:25 (good, 5.0 h)	89.7° 05:30	5.77	49%	36.8°
2040-07-31 Tue	87	—	unknown	23:20–04:25 (good, 5.08 h)	89.8° 05:25	5.83	39%	40.8°
2040-08-01 Wed	91	—	unknown	23:15–04:25 (good, 5.17 h)	89.7° 05:20	5.88	30%	47.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-03&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.