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: 09-17 (100), 09-27 (100), 09-28 (100), 09-29 (100), 09-30 (100) — by astronomy; check the weather when the night is within four days.

2040-09-17astronomy score per night — click a bar for that night2040-10-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-09-17 Mon	100	—	unknown	21:25–05:35 (good, 8.17 h)	89.7° 02:15	8.51	89%	76.9°
2040-09-18 Tue	99	—	unknown	23:30–05:35 (good, 6.08 h)	89.6° 02:10	8.56	95%	65.3°
2040-09-19 Wed	62	—	unknown	04:35–05:35 (good, 1.0 h)	89.6° 02:10	8.61	99%	54.6°
2040-09-20 Thu	50	—	unknown	20:55–05:35 (marginal, 8.67 h)	89.8° 02:05	8.66	100%	45.3°
2040-09-21 Fri	47	—	unknown	20:55–05:40 (marginal, 8.75 h)	89.8° 02:00	8.71	98%	38.6°
2040-09-22 Sat	50	—	unknown	20:55–05:40 (marginal, 8.75 h)	89.7° 01:55	8.77	94%	35.7°
2040-09-23 Sun	84	—	unknown	20:50–21:00 (good, 0.17 h)	89.5° 01:50	8.82	88%	37.2°
2040-09-24 Mon	88	—	unknown	20:50–23:40 (good, 2.83 h)	89.7° 01:50	8.87	80%	42.3°
2040-09-25 Tue	92	—	unknown	20:50–02:10 (good, 5.33 h)	89.8° 01:45	8.92	71%	49.6°
2040-09-26 Wed	97	—	unknown	20:45–05:15 (good, 8.5 h)	89.8° 01:40	8.97	62%	58.1°
2040-09-27 Thu	100	—	unknown	20:45–05:45 (good, 9.0 h)	89.6° 01:35	9.01	53%	67.2°
2040-09-28 Fri	100	—	unknown	20:40–05:45 (good, 9.08 h)	89.5° 01:35	9.06	43%	76.6°
2040-09-29 Sat	100	—	unknown	20:40–05:45 (good, 9.08 h)	89.7° 01:30	9.11	34%	86.2°
2040-09-30 Sun	100	—	unknown	20:40–05:50 (good, 9.17 h)	89.8° 01:25	9.16	25%	95.8°
2040-10-01 Mon	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.7° 01:20	9.21	18%	105.4°
2040-10-02 Tue	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.6° 01:15	9.26	11%	114.8°
2040-10-03 Wed	100	—	unknown	20:35–05:50 (good, 9.25 h)	89.6° 01:15	9.3	6%	123.9°
2040-10-04 Thu	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.7° 01:10	9.35	2%	132.3°
2040-10-05 Fri	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.8° 01:05	9.4	0%	139.2°
2040-10-06 Sat	100	—	unknown	20:30–05:55 (good, 9.42 h)	89.7° 01:00	9.44	1%	143.5°
2040-10-07 Sun	100	—	unknown	20:25–05:55 (good, 9.5 h)	89.5° 00:55	9.49	3%	144.1°
2040-10-08 Mon	100	—	unknown	20:25–05:55 (good, 9.5 h)	89.6° 00:55	9.54	8%	140.6°
2040-10-09 Tue	100	—	unknown	20:25–06:00 (good, 9.58 h)	89.8° 00:50	9.58	15%	133.8°
2040-10-10 Wed	100	—	unknown	20:20–06:00 (good, 9.67 h)	89.8° 00:45	9.63	24%	124.7°
2040-10-11 Thu	100	—	unknown	20:20–06:00 (good, 9.67 h)	89.6° 00:40	9.67	34%	114.4°
2040-10-12 Fri	100	—	unknown	20:20–06:00 (good, 9.67 h)	89.5° 00:40	9.72	45%	103.4°
2040-10-13 Sat	100	—	unknown	20:15–06:05 (good, 9.83 h)	89.7° 00:35	9.76	56%	92.0°
2040-10-14 Sun	100	—	unknown	20:15–06:05 (good, 9.83 h)	89.8° 00:30	9.8	68%	80.4°
2040-10-15 Mon	100	—	unknown	20:15–06:05 (good, 9.83 h)	89.7° 00:25	9.85	78%	69.1°
2040-10-16 Tue	93	—	unknown	23:45–06:05 (good, 6.33 h)	89.6° 00:20	9.89	87%	58.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-09-17&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.