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 Seven Sisters: 09-25 (100), 09-26 (100), 09-27 (100), 09-28 (100), 09-29 (100) — by astronomy; check the weather when the night is within four days.

2038-09-14astronomy score per night — click a bar for that night2038-10-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-09-14 Tue	33	—	unknown	00:30–05:30 (marginal, 5.0 h)	72.5° 05:35	8.32	98%	52.4°
2038-09-15 Wed	24	—	unknown	00:35–05:30 (marginal, 4.92 h)	72.5° 05:30	8.38	94%	40.5°
2038-09-16 Thu	19	—	unknown	00:30–05:30 (marginal, 5.0 h)	72.5° 05:25	8.43	89%	28.9°
2038-09-17 Fri	22	—	unknown	00:15–05:35 (marginal, 5.33 h)	72.5° 05:20	8.48	83%	17.7°
2038-09-18 Sat	30	—	unknown	00:00–05:35 (marginal, 5.58 h)	72.5° 05:15	8.53	75%	8.4°
2038-09-19 Sun	42	—	unknown	23:45–05:35 (marginal, 5.83 h)	72.5° 05:15	8.59	67%	10.2°
2038-09-20 Mon	56	—	unknown	01:40–03:50 (good, 2.17 h)	72.5° 05:10	8.64	57%	20.6°
2038-09-21 Tue	71	—	unknown	00:20–05:35 (good, 5.25 h)	72.5° 05:05	8.69	48%	32.3°
2038-09-22 Wed	84	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.74	38%	44.5°
2038-09-23 Thu	91	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 05:00	8.79	28%	57.2°
2038-09-24 Fri	99	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.84	19%	70.4°
2038-09-25 Sat	100	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:50	8.89	11%	84.0°
2038-09-26 Sun	100	—	unknown	23:40–05:45 (good, 6.08 h)	72.5° 04:45	8.94	5%	98.1°
2038-09-27 Mon	100	—	unknown	23:35–05:45 (good, 6.17 h)	72.5° 04:40	8.99	1%	112.5°
2038-09-28 Tue	100	—	unknown	23:30–05:45 (good, 6.25 h)	72.5° 04:40	9.04	0%	127.3°
2038-09-29 Wed	100	—	unknown	23:30–05:45 (good, 6.25 h)	72.5° 04:35	9.09	2%	142.1°
2038-09-30 Thu	100	—	unknown	23:25–05:50 (good, 6.42 h)	72.5° 04:30	9.14	7%	156.7°
2038-10-01 Fri	100	—	unknown	23:20–05:50 (good, 6.5 h)	72.5° 04:25	9.18	14%	169.8°
2038-10-02 Sat	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:20	9.23	23%	169.9°
2038-10-03 Sun	100	—	unknown	23:10–05:50 (good, 6.67 h)	72.5° 04:20	9.28	34%	157.4°
2038-10-04 Mon	100	—	unknown	23:10–05:50 (good, 6.67 h)	72.5° 04:15	9.33	45%	143.9°
2038-10-05 Tue	100	—	unknown	23:10–05:55 (good, 6.75 h)	72.5° 04:10	9.37	56%	130.6°
2038-10-06 Wed	100	—	unknown	23:05–05:55 (good, 6.83 h)	72.5° 04:05	9.42	66%	117.5°
2038-10-07 Thu	100	—	unknown	23:10–05:55 (good, 6.75 h)	72.5° 04:05	9.47	75%	104.7°
2038-10-08 Fri	100	—	unknown	23:15–05:55 (good, 6.67 h)	72.5° 04:00	9.51	83%	92.2°
2038-10-09 Sat	100	—	unknown	00:10–06:00 (good, 5.83 h)	72.5° 03:55	9.56	90%	79.8°
2038-10-10 Sun	100	—	unknown	01:45–06:00 (good, 4.25 h)	72.5° 03:50	9.6	95%	67.7°
2038-10-11 Mon	66	—	unknown	04:40–06:00 (good, 1.33 h)	72.5° 03:45	9.65	98%	55.7°
2038-10-12 Tue	45	—	unknown	22:50–06:00 (marginal, 7.17 h)	72.5° 03:45	9.69	100%	43.8°
2038-10-13 Wed	28	—	unknown	02:45–06:00 (marginal, 3.25 h)	72.5° 03:40	9.74	99%	32.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-09-14&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.