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: 09-25 (100), 09-26 (100), 09-27 (100), 09-28 (100), 09-29 (100) — by astronomy; check the weather when the night is within four days.

2027-09-25astronomy score per night — click a bar for that night2027-10-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-25 Sat	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.87	23%	137.3°
2027-09-26 Sun	100	—	unknown	20:45–02:10 (good, 5.42 h)	71.1° 21:00	8.92	14%	137.5°
2027-09-27 Mon	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.97	7%	133.7°
2027-09-28 Tue	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.02	2%	126.8°
2027-09-29 Wed	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.07	0%	118.0°
2027-09-30 Thu	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.12	1%	108.1°
2027-10-01 Fri	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:40	9.17	4%	98.0°
2027-10-02 Sat	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.22	10%	87.8°
2027-10-03 Sun	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.26	17%	78.1°
2027-10-04 Mon	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.31	26%	68.9°
2027-10-05 Tue	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:25	9.36	35%	60.5°
2027-10-06 Wed	95	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:20	9.4	44%	53.2°
2027-10-07 Thu	87	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.45	54%	47.4°
2027-10-08 Fri	65	—	unknown	20:25–00:55 (good, 4.5 h)	71.1° 20:15	9.5	63%	43.5°
2027-10-09 Sat	50	—	unknown	20:25–22:45 (good, 2.33 h)	71.1° 20:10	9.54	72%	42.0°
2027-10-10 Sun	41	—	unknown	20:25–01:30 (marginal, 5.08 h)	71.1° 20:05	9.59	80%	43.2°
2027-10-11 Mon	36	—	unknown	20:20–01:20 (marginal, 5.0 h)	71.1° 20:05	9.63	87%	47.0°
2027-10-12 Tue	34	—	unknown	20:20–01:10 (marginal, 4.83 h)	71.1° 20:00	9.68	93%	52.7°
2027-10-13 Wed	37	—	unknown	20:20–01:00 (marginal, 4.67 h)	71.1° 19:55	9.72	97%	60.1°
2027-10-14 Thu	43	—	unknown	20:15–20:55 (good, 0.67 h)	71.1° 19:50	9.77	99%	68.5°
2027-10-15 Fri	51	—	unknown	20:15–22:10 (good, 1.92 h)	71.1° 19:45	9.81	100%	77.6°
2027-10-16 Sat	63	—	unknown	20:15–23:05 (good, 2.83 h)	71.1° 19:45	9.85	98%	87.3°
2027-10-17 Sun	76	—	unknown	20:10–00:05 (good, 3.92 h)	71.1° 19:40	9.9	94%	97.1°
2027-10-18 Mon	89	—	unknown	20:10–00:25 (good, 4.25 h)	71.1° 19:35	9.94	88%	106.9°
2027-10-19 Tue	100	—	unknown	20:10–00:25 (good, 4.25 h)	71.1° 19:30	9.98	80%	116.4°
2027-10-20 Wed	100	—	unknown	20:10–00:25 (good, 4.25 h)	71.1° 19:25	10.02	70%	125.1°
2027-10-21 Thu	100	—	unknown	20:05–00:25 (good, 4.33 h)	71.1° 19:25	10.07	59%	132.2°
2027-10-22 Fri	100	—	unknown	20:05–00:20 (good, 4.25 h)	71.1° 19:20	10.11	48%	136.8°
2027-10-23 Sat	100	—	unknown	20:05–00:20 (good, 4.25 h)	71.1° 19:15	10.15	36%	138.1°
2027-10-24 Sun	100	—	unknown	20:00–00:20 (good, 4.33 h)	71.1° 19:10	10.19	26%	135.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-25&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.