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: 12-26 (65), 12-27 (65), 12-28 (64), 12-25 (62), 12-29 (62) — by astronomy; check the weather when the night is within four days.

2026-12-21astronomy score per night — click a bar for that night2027-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-12-21 Mon	32	—	unknown	18:35–19:00 (good, 0.42 h)	87.3° 15:20	11.51	93%	80.6°
2026-12-22 Tue	36	—	unknown	18:35–19:45 (good, 1.17 h)	87.2° 15:15	11.51	98%	89.0°
2026-12-23 Wed	42	—	unknown	18:40–20:35 (good, 1.92 h)	87.2° 15:10	11.51	100%	97.5°
2026-12-24 Thu	49	—	unknown	18:40–21:00 (good, 2.33 h)	87.2° 15:10	11.5	99%	105.7°
2026-12-25 Fri	62	—	unknown	18:40–21:10 (good, 2.5 h)	87.3° 15:05	11.5	95%	113.0°
2026-12-26 Sat	65	—	unknown	18:40–21:10 (good, 2.5 h)	87.3° 15:00	11.5	88%	118.9°
2026-12-27 Sun	65	—	unknown	18:40–21:15 (good, 2.58 h)	87.2° 14:55	11.49	79%	122.8°
2026-12-28 Mon	64	—	unknown	18:40–21:15 (good, 2.58 h)	87.2° 14:55	11.49	70%	124.4°
2026-12-29 Tue	62	—	unknown	18:40–21:10 (good, 2.5 h)	87.2° 14:50	11.48	59%	123.7°
2026-12-30 Wed	60	—	unknown	18:40–21:05 (good, 2.42 h)	87.3° 14:45	11.47	48%	121.0°
2026-12-31 Thu	57	—	unknown	18:45–21:00 (good, 2.25 h)	87.3° 14:40	11.46	38%	116.8°
2027-01-01 Fri	55	—	unknown	18:45–20:55 (good, 2.17 h)	87.2° 14:35	11.45	29%	111.5°
2027-01-02 Sat	54	—	unknown	18:45–20:55 (good, 2.17 h)	87.2° 14:35	11.44	20%	105.4°
2027-01-03 Sun	52	—	unknown	18:45–20:50 (good, 2.08 h)	87.3° 14:30	11.43	13%	99.0°
2027-01-04 Mon	50	—	unknown	18:45–20:45 (good, 2.0 h)	87.3° 14:25	11.42	8%	92.3°
2027-01-05 Tue	48	—	unknown	18:45–20:40 (good, 1.92 h)	87.2° 14:20	11.41	3%	85.6°
2027-01-06 Wed	45	—	unknown	18:50–20:35 (good, 1.75 h)	87.2° 14:15	11.39	1%	79.0°
2027-01-07 Thu	44	—	unknown	18:50–20:35 (good, 1.75 h)	87.2° 14:15	11.38	0%	72.8°
2027-01-08 Fri	42	—	unknown	18:50–20:30 (good, 1.67 h)	87.3° 14:10	11.36	1%	67.1°
2027-01-09 Sat	41	—	unknown	18:50–20:25 (good, 1.58 h)	87.3° 14:05	11.35	4%	62.3°
2027-01-10 Sun	37	—	unknown	18:50–20:20 (good, 1.5 h)	87.2° 14:00	11.33	8%	58.5°
2027-01-11 Mon	34	—	unknown	18:50–20:15 (good, 1.42 h)	87.2° 14:00	11.31	14%	56.2°
2027-01-12 Tue	29	—	unknown	18:55–20:05 (good, 1.17 h)	87.2° 13:55	11.29	22%	55.5°
2027-01-13 Wed	25	—	unknown	18:55–19:55 (good, 1.0 h)	87.3° 13:50	11.27	31%	56.7°
2027-01-14 Thu	21	—	unknown	18:55–19:40 (good, 0.75 h)	87.3° 13:45	11.25	40%	59.6°
2027-01-15 Fri	17	—	unknown	18:55–19:20 (good, 0.42 h)	87.2° 13:40	11.23	51%	64.2°
2027-01-16 Sat	14	—	unknown	18:55–20:30 (marginal, 1.58 h)	87.2° 13:40	11.21	62%	70.2°
2027-01-17 Sun	13	—	unknown	19:00–20:20 (marginal, 1.33 h)	87.3° 13:35	11.19	72%	77.3°
2027-01-18 Mon	12	—	unknown	19:00–20:15 (marginal, 1.25 h)	87.3° 13:30	11.16	82%	85.2°
2027-01-19 Tue	13	—	unknown	19:00–20:15 (marginal, 1.25 h)	87.2° 13:25	11.14	90%	93.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-12-21&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.