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: 10-07 (74), 10-08 (73), 10-06 (72), 10-05 (70), 10-09 (70) — by astronomy; check the weather when the night is within four days.

2038-09-20astronomy score per night — click a bar for that night2038-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-09-20 Mon	14	—	unknown	03:25–05:35 (marginal, 2.17 h)	42.9° 07:00	8.64	57%	27.4°
2038-09-21 Tue	20	—	unknown	03:10–05:35 (marginal, 2.42 h)	42.9° 06:55	8.69	48%	29.5°
2038-09-22 Wed	27	—	unknown	04:05–05:40 (good, 1.58 h)	42.9° 06:50	8.74	38%	35.7°
2038-09-23 Thu	36	—	unknown	03:45–05:40 (good, 1.92 h)	42.9° 06:45	8.79	28%	44.6°
2038-09-24 Fri	43	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:40	8.84	19%	55.2°
2038-09-25 Sat	49	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.89	11%	66.8°
2038-09-26 Sun	54	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.94	5%	79.3°
2038-09-27 Mon	56	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	8.99	1%	92.2°
2038-09-28 Tue	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.04	0%	105.4°
2038-09-29 Wed	60	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:20	9.09	2%	118.4°
2038-09-30 Thu	62	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:20	9.14	7%	130.8°
2038-10-01 Fri	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.18	14%	141.8°
2038-10-02 Sat	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.23	23%	149.8°
2038-10-03 Sun	67	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.28	34%	152.5°
2038-10-04 Mon	69	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.33	45%	148.8°
2038-10-05 Tue	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.37	56%	141.0°
2038-10-06 Wed	72	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.42	66%	131.2°
2038-10-07 Thu	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.47	75%	120.6°
2038-10-08 Fri	73	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 05:45	9.51	83%	109.8°
2038-10-09 Sat	70	—	unknown	02:50–06:00 (good, 3.17 h)	42.9° 05:45	9.56	90%	98.9°
2038-10-10 Sun	64	—	unknown	03:05–06:00 (good, 2.92 h)	42.9° 05:40	9.6	95%	88.0°
2038-10-11 Mon	42	—	unknown	04:25–06:00 (good, 1.58 h)	42.9° 05:35	9.65	98%	77.3°
2038-10-12 Tue	32	—	unknown	02:10–06:00 (marginal, 3.83 h)	42.9° 05:30	9.69	100%	66.8°
2038-10-13 Wed	23	—	unknown	02:25–06:00 (marginal, 3.58 h)	42.9° 05:25	9.74	99%	56.7°
2038-10-14 Thu	17	—	unknown	02:40–06:05 (marginal, 3.42 h)	42.9° 05:25	9.78	97%	47.1°
2038-10-15 Fri	13	—	unknown	03:50–06:05 (marginal, 2.25 h)	42.9° 05:20	9.82	93%	38.5°
2038-10-16 Sat	11	—	unknown	04:45–06:05 (marginal, 1.33 h)	42.9° 05:15	9.87	88%	31.7°
2038-10-17 Sun	13	—	unknown	02:15–06:05 (marginal, 3.83 h)	42.9° 05:10	9.91	81%	27.9°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-09-20&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.