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: 07-20 (100), 07-21 (100), 07-22 (100), 07-23 (100), 07-24 (100) — by astronomy; check the weather when the night is within four days.

2028-07-20astronomy score per night — click a bar for that night2028-08-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-07-20 Thu	100	—	unknown	22:55–04:10 (good, 5.25 h)	71.1° 01:25	5.25	2%	130.8°
2028-07-21 Fri	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:20	5.3	0%	136.9°
2028-07-22 Sat	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:20	5.35	1%	139.4°
2028-07-23 Sun	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:15	5.4	5%	137.6°
2028-07-24 Mon	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:10	5.45	11%	131.9°
2028-07-25 Tue	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:05	5.5	20%	123.7°
2028-07-26 Wed	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:05	5.55	30%	114.0°
2028-07-27 Thu	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 01:00	5.6	41%	103.7°
2028-07-28 Fri	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:55	5.66	52%	93.3°
2028-07-29 Sat	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:50	5.71	63%	83.0°
2028-07-30 Sun	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.77	73%	73.1°
2028-07-31 Mon	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.82	82%	63.8°
2028-08-01 Tue	96	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:40	5.88	89%	55.5°
2028-08-02 Wed	88	—	unknown	02:05–04:30 (good, 2.42 h)	71.1° 00:35	5.93	94%	48.4°
2028-08-03 Thu	47	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:30	5.99	98%	43.4°
2028-08-04 Fri	41	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:25	6.04	100%	40.8°
2028-08-05 Sat	42	—	unknown	22:25–04:35 (marginal, 6.17 h)	71.1° 00:25	6.1	100%	41.2°
2028-08-06 Sun	46	—	unknown	22:25–04:35 (marginal, 6.17 h)	71.1° 00:20	6.16	98%	44.3°
2028-08-07 Mon	55	—	unknown	22:25–22:55 (good, 0.5 h)	71.1° 00:15	6.21	94%	49.6°
2028-08-08 Tue	69	—	unknown	22:20–00:20 (good, 2.0 h)	71.1° 00:10	6.27	88%	56.4°
2028-08-09 Wed	76	—	unknown	22:20–02:20 (good, 4.0 h)	71.1° 00:05	6.33	82%	64.2°
2028-08-10 Thu	100	—	unknown	22:15–03:25 (good, 5.17 h)	71.1° 00:05	6.38	74%	72.7°
2028-08-11 Fri	100	—	unknown	22:15–04:30 (good, 6.25 h)	71.1° 00:00	6.44	65%	81.6°
2028-08-12 Sat	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 23:55	6.5	56%	90.9°
2028-08-13 Sun	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.56	46%	100.3°
2028-08-14 Mon	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.61	35%	109.8°
2028-08-15 Tue	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:45	6.67	26%	119.0°
2028-08-16 Wed	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.73	16%	127.6°
2028-08-17 Thu	100	—	unknown	22:05–04:40 (good, 6.58 h)	71.1° 23:35	6.79	9%	134.6°
2028-08-18 Fri	100	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:30	6.84	3%	138.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-07-20&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.