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 Great Orion Nebula: 10-25 (89), 10-26 (89), 10-27 (89), 10-28 (89), 10-29 (89) — by astronomy; check the weather when the night is within four days.

2038-10-18astronomy score per night — click a bar for that night2038-11-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-10-18 Mon	19	—	unknown	01:50–06:05 (marginal, 4.25 h)	42.9° 05:10	9.95	73%	28.6°
2038-10-19 Tue	28	—	unknown	01:30–06:10 (marginal, 4.67 h)	42.9° 05:05	10.0	64%	33.6°
2038-10-20 Wed	42	—	unknown	01:15–06:10 (marginal, 4.92 h)	42.9° 05:00	10.04	54%	41.6°
2038-10-21 Thu	57	—	unknown	02:05–06:10 (good, 4.08 h)	42.9° 04:55	10.08	44%	51.3°
2038-10-22 Fri	73	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 04:50	10.12	34%	62.3°
2038-10-23 Sat	84	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:50	10.16	24%	74.0°
2038-10-24 Sun	88	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.2	15%	86.5°
2038-10-25 Mon	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.24	8%	99.3°
2038-10-26 Tue	89	—	unknown	01:20–06:15 (good, 4.92 h)	42.9° 04:35	10.28	3%	112.4°
2038-10-27 Wed	89	—	unknown	01:20–06:15 (good, 4.92 h)	42.9° 04:30	10.32	0%	125.3°
2038-10-28 Thu	89	—	unknown	01:15–06:20 (good, 5.08 h)	42.9° 04:30	10.36	1%	137.2°
2038-10-29 Fri	89	—	unknown	01:10–06:20 (good, 5.17 h)	42.9° 04:25	10.39	5%	147.0°
2038-10-30 Sat	89	—	unknown	01:05–05:20 (good, 5.25 h)	42.9° 03:20	10.43	11%	152.1°
2038-10-31 Sun	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.47	20%	150.5°
2038-11-01 Mon	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.5	29%	143.4°
2038-11-02 Tue	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.54	40%	133.8°
2038-11-03 Wed	89	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:05	10.58	50%	123.2°
2038-11-04 Thu	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:00	10.61	60%	112.3°
2038-11-05 Fri	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 02:55	10.65	70%	101.4°
2038-11-06 Sat	89	—	unknown	00:05–05:30 (good, 5.42 h)	42.9° 02:55	10.68	79%	90.5°
2038-11-07 Sun	88	—	unknown	00:40–05:30 (good, 4.83 h)	42.9° 02:50	10.71	86%	79.8°
2038-11-08 Mon	86	—	unknown	02:25–05:30 (good, 3.08 h)	42.9° 02:45	10.75	92%	69.4°
2038-11-09 Tue	69	—	unknown	05:15–05:30 (good, 0.25 h)	42.9° 02:40	10.78	96%	59.2°
2038-11-10 Wed	34	—	unknown	23:50–05:30 (marginal, 5.67 h)	42.9° 02:35	10.81	99%	49.5°
2038-11-11 Thu	22	—	unknown	01:50–05:35 (marginal, 3.75 h)	42.9° 02:35	10.84	100%	40.6°
2038-11-12 Fri	15	—	unknown	04:10–05:35 (marginal, 1.42 h)	42.9° 02:30	10.87	99%	33.3°
2038-11-13 Sat	12	—	unknown	—	42.9° 02:25	10.9	96%	28.6°
2038-11-14 Sun	13	—	unknown	—	42.9° 02:20	10.93	92%	28.2°
2038-11-15 Mon	19	—	unknown	23:10–03:00 (marginal, 3.83 h)	42.9° 02:15	10.96	86%	32.2°
2038-11-16 Tue	32	—	unknown	22:45–05:20 (marginal, 6.58 h)	42.9° 02:15	10.99	79%	39.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-10-18&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.