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: 06-03 (18), 06-04 (18), 06-02 (17), 06-05 (17), 05-29 (16) — by astronomy; check the weather when the night is within four days.

2042-05-09astronomy score per night — click a bar for that night2042-06-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-09 Fri	2	—	unknown	—	89.6° 10:55	5.9	79%	104.9°
2042-05-10 Sat	2	—	unknown	04:10–04:15 (marginal, 0.08 h)	89.8° 10:50	5.84	70%	93.9°
2042-05-11 Sun	2	—	unknown	04:10–04:15 (marginal, 0.08 h)	89.8° 10:45	5.79	60%	82.6°
2042-05-12 Mon	2	—	unknown	04:05–04:10 (marginal, 0.08 h)	89.7° 10:40	5.73	49%	71.3°
2042-05-13 Tue	3	—	unknown	04:00–04:10 (marginal, 0.17 h)	89.5° 10:35	5.68	37%	60.1°
2042-05-14 Wed	4	—	unknown	03:55–04:10 (marginal, 0.25 h)	89.6° 10:35	5.62	27%	49.5°
2042-05-15 Thu	5	—	unknown	03:50–04:05 (marginal, 0.25 h)	89.8° 10:30	5.57	17%	40.4°
2042-05-16 Fri	5	—	unknown	04:20–04:50 (marginal, 0.5 h)	89.8° 10:25	5.52	9%	34.3°
2042-05-17 Sat	6	—	unknown	04:20–04:50 (marginal, 0.5 h)	89.6° 10:20	5.47	3%	33.4°
2042-05-18 Sun	6	—	unknown	04:15–04:50 (marginal, 0.58 h)	89.5° 10:20	5.41	0%	37.9°
2042-05-19 Mon	7	—	unknown	04:10–04:45 (marginal, 0.58 h)	89.7° 10:15	5.36	0%	46.2°
2042-05-20 Tue	8	—	unknown	04:05–04:45 (marginal, 0.67 h)	89.8° 10:10	5.31	3%	56.4°
2042-05-21 Wed	9	—	unknown	03:30–04:45 (marginal, 1.25 h)	89.7° 10:05	5.26	8%	67.3°
2042-05-22 Thu	9	—	unknown	04:00–04:45 (marginal, 0.75 h)	89.6° 10:00	5.22	15%	78.3°
2042-05-23 Fri	10	—	unknown	03:20–04:45 (marginal, 1.42 h)	89.6° 10:00	5.17	23%	89.2°
2042-05-24 Sat	11	—	unknown	03:50–03:55 (good, 0.08 h)	89.7° 09:55	5.12	32%	99.9°
2042-05-25 Sun	12	—	unknown	03:45–03:55 (good, 0.17 h)	89.8° 09:50	5.08	42%	110.1°
2042-05-26 Mon	12	—	unknown	03:40–03:50 (good, 0.17 h)	89.7° 09:45	5.03	52%	119.7°
2042-05-27 Tue	13	—	unknown	03:40–03:50 (good, 0.17 h)	89.5° 09:40	4.99	61%	128.7°
2042-05-28 Wed	15	—	unknown	03:35–03:50 (good, 0.25 h)	89.6° 09:40	4.95	70%	136.6°
2042-05-29 Thu	16	—	unknown	03:30–03:50 (good, 0.33 h)	89.8° 09:35	4.91	78%	142.8°
2042-05-30 Fri	14	—	unknown	03:35–03:45 (good, 0.17 h)	89.8° 09:30	4.87	86%	146.4°
2042-05-31 Sat	15	—	unknown	03:30–03:45 (good, 0.25 h)	89.6° 09:25	4.83	92%	146.5°
2042-06-01 Sun	16	—	unknown	03:30–03:45 (good, 0.25 h)	89.5° 09:25	4.79	96%	142.8°
2042-06-02 Mon	17	—	unknown	03:25–03:45 (good, 0.33 h)	89.7° 09:20	4.76	99%	136.3°
2042-06-03 Tue	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.8° 09:15	4.72	100%	127.7°
2042-06-04 Wed	18	—	unknown	03:20–03:45 (good, 0.42 h)	89.7° 09:10	4.69	99%	118.0°
2042-06-05 Thu	17	—	unknown	03:20–03:40 (good, 0.33 h)	89.6° 09:05	4.66	95%	107.4°
2042-06-06 Fri	16	—	unknown	03:25–03:40 (good, 0.25 h)	89.6° 09:05	4.63	90%	96.4°
2042-06-07 Sat	16	—	unknown	03:25–03:40 (good, 0.25 h)	89.7° 09:00	4.6	82%	85.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-09&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.