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: 01-24 (17), 02-16 (17), 01-21 (16), 01-22 (16), 01-23 (16) — by astronomy; check the weather when the night is within four days.

2027-01-18astronomy score per night — click a bar for that night2027-02-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2027-01-20 Wed	14	—	unknown	19:00–19:10 (good, 0.17 h)	87.2° 13:20	11.11	96%	101.9°
2027-01-21 Thu	16	—	unknown	19:00–19:15 (good, 0.25 h)	87.2° 13:20	11.09	100%	109.8°
2027-01-22 Fri	16	—	unknown	19:05–19:20 (good, 0.25 h)	87.3° 13:15	11.06	100%	116.5°
2027-01-23 Sat	16	—	unknown	19:05–19:20 (good, 0.25 h)	87.3° 13:10	11.04	97%	121.4°
2027-01-24 Sun	17	—	unknown	19:05–19:25 (good, 0.33 h)	87.2° 13:05	11.01	92%	124.1°
2027-01-25 Mon	16	—	unknown	19:05–19:25 (good, 0.33 h)	87.2° 13:05	10.98	84%	124.3°
2027-01-26 Tue	15	—	unknown	19:05–19:20 (good, 0.25 h)	87.2° 13:00	10.95	75%	122.2°
2027-01-27 Wed	13	—	unknown	19:10–19:15 (good, 0.08 h)	87.3° 12:55	10.92	65%	118.3°
2027-01-28 Thu	12	—	unknown	18:35–19:45 (marginal, 1.17 h)	87.3° 12:50	10.89	55%	113.2°
2027-01-29 Fri	10	—	unknown	19:10–19:40 (marginal, 0.5 h)	87.2° 12:45	10.86	45%	107.2°
2027-01-30 Sat	10	—	unknown	19:10–19:40 (marginal, 0.5 h)	87.2° 12:45	10.83	36%	100.8°
2027-01-31 Sun	9	—	unknown	19:15–19:35 (marginal, 0.33 h)	87.3° 12:40	10.8	27%	94.1°
2027-02-01 Mon	8	—	unknown	05:40–06:00 (marginal, 0.33 h)	87.3° 12:35	10.77	19%	87.3°
2027-02-02 Tue	9	—	unknown	05:35–06:00 (marginal, 0.42 h)	87.2° 12:30	10.73	12%	80.7°
2027-02-03 Wed	9	—	unknown	05:35–06:00 (marginal, 0.42 h)	87.2° 12:25	10.7	7%	74.4°
2027-02-04 Thu	9	—	unknown	05:30–05:55 (marginal, 0.42 h)	87.2° 12:25	10.66	3%	68.6°
2027-02-05 Fri	9	—	unknown	05:25–05:55 (marginal, 0.5 h)	87.3° 12:20	10.63	0%	63.4°
2027-02-06 Sat	10	—	unknown	05:20–06:30 (marginal, 1.17 h)	87.3° 12:15	10.59	0%	59.3°
2027-02-07 Sun	10	—	unknown	05:20–06:25 (marginal, 1.08 h)	87.2° 12:10	10.56	2%	56.6°
2027-02-08 Mon	11	—	unknown	05:50–05:55 (good, 0.08 h)	87.2° 12:10	10.52	5%	55.5°
2027-02-09 Tue	11	—	unknown	05:45–05:50 (good, 0.08 h)	87.3° 12:00	10.49	10%	56.2°
2027-02-10 Wed	12	—	unknown	05:40–05:50 (good, 0.17 h)	87.3° 12:00	10.45	17%	58.7°
2027-02-11 Thu	12	—	unknown	05:35–05:50 (good, 0.25 h)	87.2° 11:50	10.41	25%	62.9°
2027-02-12 Fri	13	—	unknown	05:35–05:50 (good, 0.25 h)	87.2° 11:50	10.37	35%	68.5°
2027-02-13 Sat	13	—	unknown	05:30–05:45 (good, 0.25 h)	87.3° 11:45	10.33	46%	75.2°
2027-02-14 Sun	14	—	unknown	05:25–05:45 (good, 0.33 h)	87.3° 11:40	10.3	57%	82.6°
2027-02-15 Mon	15	—	unknown	05:20–05:45 (good, 0.42 h)	87.2° 11:35	10.26	68%	90.6°
2027-02-16 Tue	17	—	unknown	05:15–05:45 (good, 0.5 h)	87.2° 11:30	10.22	78%	98.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-18&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.