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), 10-24 (88), 10-23 (84), 10-07 (74) — by astronomy; check the weather when the night is within four days.

2038-09-27astronomy score per night — click a bar for that night2038-10-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-09-27&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.