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: 06-02 (15), 06-01 (13), 05-27 (11), 05-28 (11), 05-29 (11) — by astronomy; check the weather when the night is within four days.

2040-05-04astronomy score per night — click a bar for that night2040-06-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-05-04 Fri	1	—	unknown	—	89.8° 11:10	6.16	38%	67.5°
2040-05-05 Sat	1	—	unknown	—	89.6° 11:05	6.1	27%	57.3°
2040-05-06 Sun	2	—	unknown	—	89.6° 11:05	6.04	18%	48.3°
2040-05-07 Mon	2	—	unknown	04:55–05:00 (marginal, 0.08 h)	89.7° 11:00	5.98	11%	41.3°
2040-05-08 Tue	2	—	unknown	04:50–05:00 (marginal, 0.17 h)	89.8° 10:55	5.93	5%	37.1°
2040-05-09 Wed	2	—	unknown	04:45–05:00 (marginal, 0.25 h)	89.7° 10:50	5.87	2%	36.6°
2040-05-10 Thu	3	—	unknown	04:45–04:55 (marginal, 0.17 h)	89.6° 10:45	5.82	0%	39.8°
2040-05-11 Fri	4	—	unknown	04:40–04:55 (marginal, 0.25 h)	89.6° 10:45	5.76	1%	45.7°
2040-05-12 Sat	4	—	unknown	04:35–04:55 (marginal, 0.33 h)	89.8° 10:40	5.71	3%	53.3°
2040-05-13 Sun	4	—	unknown	04:30–04:55 (marginal, 0.42 h)	89.8° 10:35	5.65	7%	61.9°
2040-05-14 Mon	5	—	unknown	03:55–04:10 (marginal, 0.25 h)	89.7° 10:30	5.6	13%	71.0°
2040-05-15 Tue	5	—	unknown	04:25–04:50 (marginal, 0.42 h)	89.5° 10:25	5.55	20%	80.3°
2040-05-16 Wed	6	—	unknown	04:20–04:50 (marginal, 0.5 h)	89.7° 10:25	5.49	28%	89.8°
2040-05-17 Thu	6	—	unknown	04:15–04:50 (marginal, 0.58 h)	89.8° 10:20	5.44	37%	99.4°
2040-05-18 Fri	6	—	unknown	04:10–04:45 (marginal, 0.58 h)	89.8° 10:15	5.39	46%	108.9°
2040-05-19 Sat	7	—	unknown	04:10–04:45 (marginal, 0.58 h)	89.6° 10:10	5.34	56%	118.1°
2040-05-20 Sun	8	—	unknown	04:05–04:45 (marginal, 0.67 h)	89.5° 10:10	5.29	66%	127.0°
2040-05-21 Mon	8	—	unknown	04:00–04:45 (marginal, 0.75 h)	89.7° 10:05	5.24	75%	134.9°
2040-05-22 Tue	8	—	unknown	04:05–04:45 (marginal, 0.67 h)	89.8° 10:00	5.19	84%	140.9°
2040-05-23 Wed	9	—	unknown	03:20–03:55 (marginal, 0.58 h)	89.7° 09:55	5.15	91%	143.6°
2040-05-24 Thu	9	—	unknown	03:15–03:55 (marginal, 0.67 h)	89.6° 09:50	5.1	97%	142.0°
2040-05-25 Fri	9	—	unknown	03:10–03:50 (marginal, 0.67 h)	89.6° 09:50	5.05	100%	136.0°
2040-05-26 Sat	10	—	unknown	03:05–04:40 (marginal, 1.58 h)	89.8° 09:45	5.01	100%	127.1°
2040-05-27 Sun	11	—	unknown	03:05–04:40 (marginal, 1.58 h)	89.8° 09:40	4.97	97%	116.5°
2040-05-28 Mon	11	—	unknown	03:00–04:40 (marginal, 1.67 h)	89.7° 09:35	4.93	91%	105.0°
2040-05-29 Tue	11	—	unknown	02:55–04:35 (marginal, 1.67 h)	89.5° 09:30	4.89	84%	93.1°
2040-05-30 Wed	10	—	unknown	02:50–03:45 (marginal, 0.92 h)	89.7° 09:30	4.85	74%	81.4°
2040-05-31 Thu	11	—	unknown	02:50–04:35 (marginal, 1.75 h)	89.8° 09:25	4.81	63%	70.1°
2040-06-01 Fri	13	—	unknown	03:40–03:45 (good, 0.08 h)	89.8° 09:20	4.77	52%	59.6°
2040-06-02 Sat	15	—	unknown	03:30–03:45 (good, 0.25 h)	89.6° 09:15	4.74	41%	50.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-04&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.