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: 10-19 (100), 10-20 (100), 10-21 (100), 10-22 (100), 10-23 (100) — by astronomy; check the weather when the night is within four days.

2027-10-17astronomy score per night — click a bar for that night2027-11-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-10-17 Sun	75	—	unknown	20:10–23:55 (good, 3.75 h)	87.2° 20:35	9.9	94%	77.1°
2027-10-18 Mon	82	—	unknown	20:10–01:00 (good, 4.83 h)	87.2° 20:35	9.94	88%	84.6°
2027-10-19 Tue	100	—	unknown	20:10–02:10 (good, 6.0 h)	87.2° 20:30	9.98	80%	92.5°
2027-10-20 Wed	100	—	unknown	20:10–02:25 (good, 6.25 h)	87.3° 20:25	10.02	70%	100.4°
2027-10-21 Thu	100	—	unknown	20:05–02:30 (good, 6.42 h)	87.2° 20:20	10.07	59%	107.9°
2027-10-22 Fri	100	—	unknown	20:05–02:30 (good, 6.42 h)	87.2° 20:15	10.11	48%	114.7°
2027-10-23 Sat	100	—	unknown	20:05–02:30 (good, 6.42 h)	87.2° 20:15	10.15	36%	120.2°
2027-10-24 Sun	100	—	unknown	20:00–02:30 (good, 6.5 h)	87.3° 20:10	10.19	26%	123.9°
2027-10-25 Mon	100	—	unknown	20:00–02:25 (good, 6.42 h)	87.3° 20:05	10.23	16%	125.4°
2027-10-26 Tue	100	—	unknown	20:00–02:20 (good, 6.33 h)	87.2° 20:00	10.27	9%	124.3°
2027-10-27 Wed	100	—	unknown	20:00–02:20 (good, 6.33 h)	87.2° 20:00	10.31	4%	120.9°
2027-10-28 Thu	100	—	unknown	19:55–02:15 (good, 6.33 h)	87.2° 19:55	10.34	1%	115.7°
2027-10-29 Fri	100	—	unknown	19:55–02:10 (good, 6.25 h)	87.3° 19:50	10.38	0%	109.3°
2027-10-30 Sat	100	—	unknown	19:55–02:05 (good, 6.17 h)	87.3° 19:45	10.42	2%	102.2°
2027-10-31 Sun	100	—	unknown	18:55–01:00 (good, 6.08 h)	87.2° 18:40	10.46	6%	94.7°
2027-11-01 Mon	100	—	unknown	18:55–01:00 (good, 6.08 h)	87.2° 18:40	10.49	12%	87.3°
2027-11-02 Tue	100	—	unknown	18:50–00:55 (good, 6.08 h)	87.2° 18:35	10.53	20%	80.1°
2027-11-03 Wed	100	—	unknown	18:50–00:50 (good, 6.0 h)	87.3° 18:30	10.57	28%	73.4°
2027-11-04 Thu	95	—	unknown	18:50–00:45 (good, 5.92 h)	87.2° 18:25	10.6	37%	67.4°
2027-11-05 Fri	88	—	unknown	18:50–00:40 (good, 5.83 h)	87.2° 18:20	10.64	46%	62.3°
2027-11-06 Sat	81	—	unknown	18:45–00:40 (good, 5.92 h)	87.2° 18:20	10.67	56%	58.2°
2027-11-07 Sun	69	—	unknown	18:45–00:05 (good, 5.33 h)	87.3° 18:15	10.7	65%	55.5°
2027-11-08 Mon	59	—	unknown	18:45–21:30 (good, 2.75 h)	87.3° 18:10	10.74	74%	54.5°
2027-11-09 Tue	49	—	unknown	18:45–00:50 (marginal, 6.08 h)	87.2° 18:05	10.77	82%	55.3°
2027-11-10 Wed	44	—	unknown	18:45–00:35 (marginal, 5.83 h)	87.2° 18:00	10.8	89%	57.9°
2027-11-11 Thu	43	—	unknown	18:45–00:25 (marginal, 5.67 h)	87.2° 18:00	10.83	94%	62.2°
2027-11-12 Fri	47	—	unknown	18:40–18:50 (good, 0.17 h)	87.3° 17:55	10.86	98%	67.9°
2027-11-13 Sat	54	—	unknown	18:40–20:15 (good, 1.58 h)	87.3° 17:50	10.89	100%	74.7°
2027-11-14 Sun	66	—	unknown	18:40–21:25 (good, 2.75 h)	87.2° 17:45	10.92	99%	82.3°
2027-11-15 Mon	80	—	unknown	18:40–22:25 (good, 3.75 h)	87.2° 17:45	10.95	96%	90.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-10-17&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.