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: 06-27 (100), 06-28 (100), 06-29 (100), 06-30 (100), 07-01 (100) — by astronomy; check the weather when the night is within four days.

2027-06-18astronomy score per night — click a bar for that night2027-07-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-06-18 Fri	50	—	unknown	01:40–03:40 (good, 2.0 h)	71.1° 03:35	4.43	100%	59.8°
2027-06-19 Sat	44	—	unknown	23:10–03:40 (marginal, 4.5 h)	71.1° 03:30	4.42	99%	52.8°
2027-06-20 Sun	41	—	unknown	23:15–03:40 (marginal, 4.42 h)	71.1° 03:25	4.42	97%	47.1°
2027-06-21 Mon	43	—	unknown	23:15–03:40 (marginal, 4.42 h)	71.1° 03:25	4.42	92%	43.5°
2027-06-22 Tue	70	—	unknown	23:15–23:30 (good, 0.25 h)	71.1° 03:20	4.42	87%	42.3°
2027-06-23 Wed	80	—	unknown	23:15–02:35 (good, 3.33 h)	71.1° 03:15	4.43	80%	43.7°
2027-06-24 Thu	90	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.43	72%	47.6°
2027-06-25 Fri	95	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.44	62%	53.4°
2027-06-26 Sat	98	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	53%	60.7°
2027-06-27 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.46	43%	69.1°
2027-06-28 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 02:55	4.48	32%	78.4°
2027-06-29 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:50	4.49	23%	88.2°
2027-06-30 Wed	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:50	4.51	14%	98.4°
2027-07-01 Thu	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:45	4.53	7%	108.7°
2027-07-02 Fri	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:40	4.55	2%	118.7°
2027-07-03 Sat	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:35	4.58	0%	127.6°
2027-07-04 Sun	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:30	4.6	1%	134.3°
2027-07-05 Mon	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:30	4.63	5%	137.6°
2027-07-06 Tue	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:25	4.66	11%	136.7°
2027-07-07 Wed	100	—	unknown	23:10–03:50 (good, 4.67 h)	71.1° 02:20	4.69	20%	132.0°
2027-07-08 Thu	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:15	4.72	30%	124.8°
2027-07-09 Fri	100	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:10	4.76	41%	116.1°
2027-07-10 Sat	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:10	4.79	52%	106.9°
2027-07-11 Sun	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:05	4.83	62%	97.4°
2027-07-12 Mon	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:00	4.87	72%	87.9°
2027-07-13 Tue	100	—	unknown	23:00–03:55 (good, 4.92 h)	71.1° 01:55	4.9	80%	78.7°
2027-07-14 Wed	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:55	4.95	88%	69.9°
2027-07-15 Thu	100	—	unknown	23:05–04:00 (good, 4.92 h)	71.1° 01:50	4.99	93%	61.7°
2027-07-16 Fri	62	—	unknown	01:35–04:00 (good, 2.42 h)	71.1° 01:45	5.03	97%	54.4°
2027-07-17 Sat	49	—	unknown	23:00–04:00 (marginal, 5.0 h)	71.1° 01:40	5.07	100%	48.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-06-18&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.