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: 08-05 (100), 08-06 (100), 08-07 (100), 08-08 (100), 08-09 (100) — by astronomy; check the weather when the night is within four days.

2027-08-05astronomy score per night — click a bar for that night2027-09-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-05 Thu	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:25	6.06	17%	119.3°
2027-08-06 Fri	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:20	6.11	26%	109.9°
2027-08-07 Sat	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:20	6.17	37%	100.1°
2027-08-08 Sun	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:15	6.23	47%	90.5°
2027-08-09 Mon	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:10	6.28	57%	81.1°
2027-08-10 Tue	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:05	6.34	67%	72.1°
2027-08-11 Wed	100	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:05	6.4	76%	63.7°
2027-08-12 Thu	97	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:00	6.46	84%	56.2°
2027-08-13 Fri	89	—	unknown	00:05–04:45 (good, 4.67 h)	71.1° 23:55	6.51	90%	49.8°
2027-08-14 Sat	81	—	unknown	04:20–04:45 (good, 0.42 h)	71.1° 23:50	6.57	95%	45.1°
2027-08-15 Sun	46	—	unknown	22:10–04:45 (marginal, 6.58 h)	71.1° 23:45	6.63	98%	42.5°
2027-08-16 Mon	44	—	unknown	22:05–04:50 (marginal, 6.75 h)	71.1° 23:45	6.69	100%	42.6°
2027-08-17 Tue	45	—	unknown	22:05–04:45 (marginal, 6.67 h)	71.1° 23:40	6.74	100%	45.3°
2027-08-18 Wed	51	—	unknown	21:25–04:40 (marginal, 7.25 h)	71.1° 23:35	6.8	98%	50.2°
2027-08-19 Thu	62	—	unknown	22:00–23:15 (good, 1.25 h)	71.1° 23:30	6.86	94%	56.7°
2027-08-20 Fri	73	—	unknown	22:00–01:10 (good, 3.17 h)	71.1° 23:25	6.92	88%	64.5°
2027-08-21 Sat	79	—	unknown	22:00–02:25 (good, 4.42 h)	71.1° 23:25	6.97	81%	73.2°
2027-08-22 Sun	100	—	unknown	21:55–03:30 (good, 5.58 h)	71.1° 23:20	7.03	72%	82.3°
2027-08-23 Mon	100	—	unknown	21:55–04:00 (good, 6.08 h)	71.1° 23:15	7.09	62%	91.9°
2027-08-24 Tue	100	—	unknown	21:50–04:05 (good, 6.25 h)	71.1° 23:10	7.15	52%	101.6°
2027-08-25 Wed	100	—	unknown	21:50–04:05 (good, 6.25 h)	71.1° 23:10	7.2	41%	111.3°
2027-08-26 Thu	100	—	unknown	21:50–04:05 (good, 6.25 h)	71.1° 23:05	7.26	30%	120.6°
2027-08-27 Fri	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.32	20%	128.8°
2027-08-28 Sat	100	—	unknown	21:45–04:00 (good, 6.25 h)	71.1° 22:55	7.37	11%	134.9°
2027-08-29 Sun	100	—	unknown	21:40–04:00 (good, 6.33 h)	71.1° 22:50	7.43	5%	137.7°
2027-08-30 Mon	100	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.49	1%	136.3°
2027-08-31 Tue	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:45	7.54	0%	131.0°
2027-09-01 Wed	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:40	7.6	2%	123.1°
2027-09-02 Thu	100	—	unknown	21:35–03:40 (good, 6.08 h)	71.1° 22:35	7.65	7%	113.8°
2027-09-03 Fri	100	—	unknown	21:30–03:40 (good, 6.17 h)	71.1° 22:30	7.71	14%	103.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-05&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.