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: 06-23 (100), 06-24 (100), 06-25 (100), 06-26 (100), 06-27 (100) — by astronomy; check the weather when the night is within four days.

2038-06-22astronomy score per night — click a bar for that night2038-07-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-06-22 Tue	98	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:20	4.43	65%	56.6°
2038-06-23 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	56%	63.8°
2038-06-24 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.44	46%	71.6°
2038-06-25 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	37%	79.8°
2038-06-26 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.46	28%	88.2°
2038-06-27 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.47	20%	96.6°
2038-06-28 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 02:55	4.48	13%	105.0°
2038-06-29 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:50	4.5	7%	113.2°
2038-06-30 Wed	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:45	4.52	3%	120.8°
2038-07-01 Thu	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:45	4.54	0%	127.4°
2038-07-02 Fri	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:40	4.56	0%	132.5°
2038-07-03 Sat	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:35	4.59	2%	135.2°
2038-07-04 Sun	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:30	4.61	6%	135.0°
2038-07-05 Mon	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:25	4.64	13%	131.6°
2038-07-06 Tue	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:25	4.67	21%	125.7°
2038-07-07 Wed	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:20	4.7	31%	118.0°
2038-07-08 Thu	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:15	4.73	42%	108.9°
2038-07-09 Fri	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:10	4.77	53%	99.2°
2038-07-10 Sat	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:10	4.8	64%	89.1°
2038-07-11 Sun	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:05	4.84	75%	78.9°
2038-07-12 Mon	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:00	4.88	84%	69.2°
2038-07-13 Tue	100	—	unknown	23:45–03:55 (good, 4.17 h)	71.1° 01:55	4.92	92%	60.2°
2038-07-14 Wed	58	—	unknown	02:25–04:00 (good, 1.58 h)	71.1° 01:50	4.96	97%	52.6°
2038-07-15 Thu	47	—	unknown	23:00–04:00 (marginal, 5.0 h)	71.1° 01:50	5.0	100%	47.2°
2038-07-16 Fri	42	—	unknown	23:00–04:00 (marginal, 5.0 h)	71.1° 01:45	5.05	100%	44.6°
2038-07-17 Sat	47	—	unknown	22:55–04:05 (marginal, 5.17 h)	71.1° 01:40	5.09	98%	45.2°
2038-07-18 Sun	57	—	unknown	22:55–00:25 (good, 1.5 h)	71.1° 01:35	5.14	93%	48.7°
2038-07-19 Mon	96	—	unknown	22:55–02:15 (good, 3.33 h)	71.1° 01:30	5.18	87%	54.3°
2038-07-20 Tue	99	—	unknown	22:55–04:00 (good, 5.08 h)	71.1° 01:30	5.23	80%	61.2°
2038-07-21 Wed	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:25	5.28	71%	68.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-06-22&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.