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 HD 189733: 09-05 (100), 09-16 (100), 09-17 (100), 09-18 (100), 09-19 (100) — by astronomy; check the weather when the night is within four days.

2038-09-05astronomy score per night — click a bar for that night2038-10-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-09-05 Sun	100	—	unknown	21:25–03:30 (good, 6.08 h)	71.1° 22:25	7.84	48%	64.7°
2038-09-06 Mon	98	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.89	60%	56.5°
2038-09-07 Tue	91	—	unknown	21:25–03:20 (good, 5.92 h)	71.1° 22:15	7.95	70%	50.0°
2038-09-08 Wed	84	—	unknown	21:20–03:20 (good, 6.0 h)	71.1° 22:10	8.0	79%	45.9°
2038-09-09 Thu	53	—	unknown	21:20–03:40 (marginal, 6.33 h)	71.1° 22:10	8.06	87%	44.6°
2038-09-10 Fri	47	—	unknown	21:15–03:25 (marginal, 6.17 h)	71.1° 22:05	8.11	93%	46.2°
2038-09-11 Sat	47	—	unknown	21:15–03:15 (marginal, 6.0 h)	71.1° 22:00	8.16	97%	50.4°
2038-09-12 Sun	50	—	unknown	21:15–21:30 (good, 0.25 h)	71.1° 21:55	8.22	100%	56.4°
2038-09-13 Mon	58	—	unknown	21:10–22:40 (good, 1.5 h)	71.1° 21:50	8.27	100%	63.6°
2038-09-14 Tue	68	—	unknown	21:10–00:00 (good, 2.83 h)	71.1° 21:50	8.32	98%	71.5°
2038-09-15 Wed	78	—	unknown	21:10–00:50 (good, 3.67 h)	71.1° 21:45	8.38	94%	79.7°
2038-09-16 Thu	100	—	unknown	21:05–01:40 (good, 4.58 h)	71.1° 21:40	8.43	89%	88.2°
2038-09-17 Fri	100	—	unknown	21:05–02:15 (good, 5.17 h)	71.1° 21:35	8.48	83%	96.5°
2038-09-18 Sat	100	—	unknown	21:00–02:20 (good, 5.33 h)	71.1° 21:30	8.53	75%	104.8°
2038-09-19 Sun	100	—	unknown	21:00–02:25 (good, 5.42 h)	71.1° 21:30	8.59	67%	112.7°
2038-09-20 Mon	100	—	unknown	21:00–02:25 (good, 5.42 h)	71.1° 21:25	8.64	57%	120.1°
2038-09-21 Tue	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:20	8.69	48%	126.6°
2038-09-22 Wed	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.74	38%	131.8°
2038-09-23 Thu	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:15	8.79	28%	134.8°
2038-09-24 Fri	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.84	19%	135.0°
2038-09-25 Sat	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.89	11%	132.1°
2038-09-26 Sun	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.94	5%	126.3°
2038-09-27 Mon	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 20:55	8.99	1%	118.3°
2038-09-28 Tue	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.04	0%	108.8°
2038-09-29 Wed	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.09	2%	98.4°
2038-09-30 Thu	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.14	7%	87.7°
2038-10-01 Fri	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:40	9.18	14%	77.3°
2038-10-02 Sat	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:35	9.23	23%	67.4°
2038-10-03 Sun	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.28	34%	58.7°
2038-10-04 Mon	94	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.33	45%	51.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-09-05&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.