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 Vega: 03-13 (91), 03-14 (91), 03-15 (90), 03-16 (90), 03-11 (89) — by astronomy; check the weather when the night is within four days.

2027-02-20astronomy score per night — click a bar for that night2027-03-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-02-20 Sat	47	—	unknown	03:20–05:40 (good, 2.33 h)	87.1° 08:55	10.05	100%	110.1°
2027-02-21 Sun	44	—	unknown	03:20–05:35 (good, 2.25 h)	87.1° 08:50	10.01	99%	105.4°
2027-02-22 Mon	43	—	unknown	03:20–05:35 (good, 2.25 h)	87.1° 08:45	9.97	95%	100.0°
2027-02-23 Tue	42	—	unknown	03:20–05:35 (good, 2.25 h)	87.1° 08:45	9.92	89%	94.2°
2027-02-24 Wed	43	—	unknown	03:15–05:35 (good, 2.33 h)	87.1° 08:40	9.88	81%	88.4°
2027-02-25 Thu	44	—	unknown	03:05–05:30 (good, 2.42 h)	87.1° 08:35	9.84	72%	82.9°
2027-02-26 Fri	48	—	unknown	03:00–05:30 (good, 2.5 h)	87.1° 08:30	9.79	62%	77.8°
2027-02-27 Sat	52	—	unknown	02:50–05:30 (good, 2.67 h)	87.1° 08:25	9.75	53%	73.3°
2027-02-28 Sun	58	—	unknown	02:30–05:25 (good, 2.92 h)	87.1° 08:25	9.7	43%	69.6°
2027-03-01 Mon	64	—	unknown	02:25–05:25 (good, 3.0 h)	87.1° 08:20	9.66	34%	66.8°
2027-03-02 Tue	71	—	unknown	02:20–05:25 (good, 3.08 h)	87.1° 08:15	9.61	25%	65.1°
2027-03-03 Wed	77	—	unknown	02:15–05:20 (good, 3.08 h)	87.1° 08:10	9.57	18%	64.4°
2027-03-04 Thu	81	—	unknown	02:15–05:20 (good, 3.08 h)	87.1° 08:10	9.52	11%	64.9°
2027-03-05 Fri	82	—	unknown	02:10–05:20 (good, 3.17 h)	87.1° 08:05	9.47	6%	66.6°
2027-03-06 Sat	82	—	unknown	02:05–05:15 (good, 3.17 h)	87.1° 08:00	9.43	2%	69.4°
2027-03-07 Sun	84	—	unknown	02:00–05:15 (good, 3.25 h)	87.1° 07:55	9.38	0%	73.1°
2027-03-08 Mon	86	—	unknown	02:00–05:15 (good, 3.25 h)	87.1° 07:50	9.33	0%	77.6°
2027-03-09 Tue	86	—	unknown	01:55–05:10 (good, 3.25 h)	87.1° 07:50	9.28	3%	82.8°
2027-03-10 Wed	88	—	unknown	01:50–05:10 (good, 3.33 h)	87.1° 07:45	9.23	7%	88.3°
2027-03-11 Thu	89	—	unknown	01:45–05:10 (good, 3.42 h)	87.1° 07:40	9.19	13%	94.0°
2027-03-12 Fri	89	—	unknown	01:40–05:05 (good, 3.42 h)	87.1° 07:35	9.14	21%	99.6°
2027-03-13 Sat	91	—	unknown	01:40–05:05 (good, 3.42 h)	87.1° 07:30	9.09	31%	104.8°
2027-03-14 Sun	91	—	unknown	01:35–05:05 (good, 3.5 h)	87.1° 07:30	9.04	42%	109.4°
2027-03-15 Mon	90	—	unknown	01:35–05:00 (good, 3.42 h)	87.1° 07:25	8.99	53%	112.9°
2027-03-16 Tue	90	—	unknown	01:35–05:00 (good, 3.42 h)	87.1° 07:20	8.94	64%	115.1°
2027-03-17 Wed	89	—	unknown	01:35–05:00 (good, 3.42 h)	87.1° 07:15	8.89	75%	115.6°
2027-03-18 Thu	86	—	unknown	01:30–04:55 (good, 3.42 h)	87.1° 07:15	8.84	84%	114.4°
2027-03-19 Fri	75	—	unknown	01:35–04:55 (good, 3.33 h)	87.1° 07:10	8.79	92%	111.6°
2027-03-20 Sat	70	—	unknown	01:35–04:55 (good, 3.33 h)	87.1° 07:05	8.73	97%	107.5°
2027-03-21 Sun	64	—	unknown	01:35–04:50 (good, 3.25 h)	87.1° 07:00	8.68	100%	102.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-02-20&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.