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 North America Nebula: 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100) — by astronomy; check the weather when the night is within four days.

2027-09-18astronomy score per night — click a bar for that night2027-10-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-18 Sat	72	—	unknown	21:00–23:45 (good, 2.75 h)	87.2° 22:30	8.52	91%	65.6°
2027-09-19 Sun	78	—	unknown	21:00–01:40 (good, 4.67 h)	87.2° 22:25	8.57	84%	71.7°
2027-09-20 Mon	100	—	unknown	21:00–02:55 (good, 5.92 h)	87.2° 22:25	8.62	76%	78.7°
2027-09-21 Tue	100	—	unknown	20:55–04:05 (good, 7.17 h)	87.2° 22:20	8.67	66%	86.3°
2027-09-22 Wed	100	—	unknown	20:55–04:15 (good, 7.33 h)	87.3° 22:15	8.72	56%	94.1°
2027-09-23 Thu	100	—	unknown	20:55–04:20 (good, 7.42 h)	87.2° 22:10	8.77	44%	102.0°
2027-09-24 Fri	100	—	unknown	20:50–04:20 (good, 7.5 h)	87.2° 22:05	8.82	33%	109.4°
2027-09-25 Sat	100	—	unknown	20:50–04:20 (good, 7.5 h)	87.2° 22:05	8.87	23%	116.1°
2027-09-26 Sun	100	—	unknown	20:45–04:20 (good, 7.58 h)	87.3° 22:00	8.92	14%	121.3°
2027-09-27 Mon	100	—	unknown	20:45–04:15 (good, 7.5 h)	87.3° 21:55	8.97	7%	124.5°
2027-09-28 Tue	100	—	unknown	20:45–04:10 (good, 7.42 h)	87.2° 21:50	9.02	2%	125.2°
2027-09-29 Wed	100	—	unknown	20:40–04:10 (good, 7.5 h)	87.2° 21:50	9.07	0%	123.2°
2027-09-30 Thu	100	—	unknown	20:40–04:05 (good, 7.42 h)	87.2° 21:45	9.12	1%	119.1°
2027-10-01 Fri	100	—	unknown	20:40–04:00 (good, 7.33 h)	87.3° 21:40	9.17	4%	113.3°
2027-10-02 Sat	100	—	unknown	20:35–03:55 (good, 7.33 h)	87.3° 21:35	9.22	10%	106.5°
2027-10-03 Sun	100	—	unknown	20:35–03:50 (good, 7.25 h)	87.2° 21:30	9.26	17%	99.3°
2027-10-04 Mon	100	—	unknown	20:35–03:50 (good, 7.25 h)	87.2° 21:30	9.31	26%	92.0°
2027-10-05 Tue	100	—	unknown	20:30–03:45 (good, 7.25 h)	87.2° 21:25	9.36	35%	84.8°
2027-10-06 Wed	100	—	unknown	20:30–03:40 (good, 7.17 h)	87.3° 21:20	9.4	44%	77.9°
2027-10-07 Thu	100	—	unknown	20:30–03:35 (good, 7.08 h)	87.2° 21:15	9.45	54%	71.5°
2027-10-08 Fri	92	—	unknown	20:25–03:30 (good, 7.08 h)	87.2° 21:10	9.5	63%	65.8°
2027-10-09 Sat	85	—	unknown	20:25–03:30 (good, 7.08 h)	87.2° 21:10	9.54	72%	61.0°
2027-10-10 Sun	67	—	unknown	20:25–02:30 (good, 6.08 h)	87.3° 21:05	9.59	80%	57.4°
2027-10-11 Mon	58	—	unknown	20:20–03:50 (marginal, 7.5 h)	87.3° 21:00	9.63	87%	55.2°
2027-10-12 Tue	53	—	unknown	20:20–03:40 (marginal, 7.33 h)	87.2° 20:55	9.68	93%	54.8°
2027-10-13 Wed	49	—	unknown	20:20–03:20 (marginal, 7.0 h)	87.2° 20:55	9.72	97%	56.1°
2027-10-14 Thu	51	—	unknown	20:15–03:10 (marginal, 6.92 h)	87.2° 20:50	9.77	99%	59.3°
2027-10-15 Fri	57	—	unknown	20:15–20:45 (good, 0.5 h)	87.3° 20:45	9.81	100%	64.1°
2027-10-16 Sat	68	—	unknown	20:15–22:10 (good, 1.92 h)	87.3° 20:40	9.85	98%	70.1°
2027-10-17 Sun	75	—	unknown	20:10–23:55 (good, 3.75 h)	87.2° 20:35	9.9	94%	77.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-18&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.