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: 03-16 (39), 03-14 (38), 03-15 (38), 03-17 (38), 03-18 (38) — by astronomy; check the weather when the night is within four days.

2027-02-17astronomy score per night — click a bar for that night2027-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-02-17 Wed	15	—	unknown	05:25–05:40 (good, 0.25 h)	87.2° 11:30	10.18	87%	106.6°
2027-02-18 Thu	15	—	unknown	05:20–05:40 (good, 0.33 h)	87.3° 11:25	10.13	94%	113.7°
2027-02-19 Fri	16	—	unknown	05:15–05:40 (good, 0.42 h)	87.3° 11:20	10.09	98%	119.4°
2027-02-20 Sat	17	—	unknown	05:15–05:40 (good, 0.42 h)	87.2° 11:15	10.05	100%	123.2°
2027-02-21 Sun	16	—	unknown	05:10–05:35 (good, 0.42 h)	87.2° 11:15	10.01	99%	124.6°
2027-02-22 Mon	17	—	unknown	05:05–05:35 (good, 0.5 h)	87.2° 11:10	9.97	95%	123.4°
2027-02-23 Tue	18	—	unknown	05:00–05:35 (good, 0.58 h)	87.3° 11:05	9.92	89%	120.1°
2027-02-24 Wed	19	—	unknown	05:00–05:35 (good, 0.58 h)	87.3° 11:00	9.88	81%	115.3°
2027-02-25 Thu	19	—	unknown	04:55–05:30 (good, 0.58 h)	87.2° 10:55	9.84	72%	109.4°
2027-02-26 Fri	19	—	unknown	04:50–05:30 (good, 0.67 h)	87.2° 10:55	9.79	62%	102.9°
2027-02-27 Sat	20	—	unknown	04:45–05:30 (good, 0.75 h)	87.3° 10:50	9.75	53%	96.1°
2027-02-28 Sun	21	—	unknown	04:40–05:25 (good, 0.75 h)	87.3° 10:45	9.7	43%	89.3°
2027-03-01 Mon	23	—	unknown	04:35–05:25 (good, 0.83 h)	87.2° 10:40	9.66	34%	82.6°
2027-03-02 Tue	25	—	unknown	04:20–05:25 (good, 1.08 h)	87.2° 10:35	9.61	25%	76.2°
2027-03-03 Wed	27	—	unknown	04:20–05:20 (good, 1.0 h)	87.2° 10:35	9.57	18%	70.2°
2027-03-04 Thu	30	—	unknown	04:15–05:20 (good, 1.08 h)	87.3° 10:30	9.52	11%	64.8°
2027-03-05 Fri	31	—	unknown	04:10–05:20 (good, 1.17 h)	87.3° 10:25	9.47	6%	60.4°
2027-03-06 Sat	31	—	unknown	04:05–05:15 (good, 1.17 h)	87.2° 10:20	9.43	2%	57.2°
2027-03-07 Sun	32	—	unknown	04:05–05:15 (good, 1.17 h)	87.2° 10:20	9.38	0%	55.6°
2027-03-08 Mon	33	—	unknown	04:00–05:15 (good, 1.25 h)	87.2° 10:15	9.33	0%	55.8°
2027-03-09 Tue	33	—	unknown	03:55–05:10 (good, 1.25 h)	87.3° 10:10	9.28	3%	58.0°
2027-03-10 Wed	35	—	unknown	03:50–05:10 (good, 1.33 h)	87.3° 10:05	9.23	7%	61.8°
2027-03-11 Thu	36	—	unknown	03:45–05:10 (good, 1.42 h)	87.2° 10:00	9.19	13%	67.2°
2027-03-12 Fri	35	—	unknown	03:45–05:05 (good, 1.33 h)	87.2° 10:00	9.14	21%	73.6°
2027-03-13 Sat	37	—	unknown	03:40–05:05 (good, 1.42 h)	87.2° 09:55	9.09	31%	80.9°
2027-03-14 Sun	38	—	unknown	03:35–05:05 (good, 1.5 h)	87.3° 09:50	9.04	42%	88.6°
2027-03-15 Mon	38	—	unknown	03:30–05:00 (good, 1.5 h)	87.2° 09:45	8.99	53%	96.5°
2027-03-16 Tue	39	—	unknown	03:25–05:00 (good, 1.58 h)	87.2° 09:40	8.94	64%	104.3°
2027-03-17 Wed	38	—	unknown	03:35–05:00 (good, 1.42 h)	87.2° 09:40	8.89	75%	111.4°
2027-03-18 Thu	38	—	unknown	03:30–04:55 (good, 1.42 h)	87.3° 09:35	8.84	84%	117.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-02-17&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.