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: 05-02 (82), 05-01 (77), 04-30 (73), 04-29 (67), 04-12 (62) — by astronomy; check the weather when the night is within four days.

2027-04-03astronomy score per night — click a bar for that night2027-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-03 Sat	54	—	unknown	03:15–05:25 (good, 2.17 h)	87.2° 09:30	7.99	10%	55.9°
2027-04-04 Sun	55	—	unknown	03:10–05:25 (good, 2.25 h)	87.2° 09:25	7.93	5%	55.5°
2027-04-05 Mon	55	—	unknown	03:10–05:20 (good, 2.17 h)	87.2° 09:25	7.87	1%	57.1°
2027-04-06 Tue	56	—	unknown	03:05–05:20 (good, 2.25 h)	87.3° 09:20	7.82	0%	60.5°
2027-04-07 Wed	58	—	unknown	03:00–05:20 (good, 2.33 h)	87.3° 09:15	7.76	1%	65.6°
2027-04-08 Thu	58	—	unknown	02:55–05:15 (good, 2.33 h)	87.2° 09:10	7.71	5%	71.9°
2027-04-09 Fri	59	—	unknown	02:55–05:15 (good, 2.33 h)	87.2° 09:10	7.65	10%	79.1°
2027-04-10 Sat	59	—	unknown	02:50–05:10 (good, 2.33 h)	87.2° 09:05	7.59	18%	86.9°
2027-04-11 Sun	61	—	unknown	02:45–05:10 (good, 2.42 h)	87.3° 09:00	7.54	28%	94.9°
2027-04-12 Mon	62	—	unknown	02:40–05:10 (good, 2.5 h)	87.2° 08:55	7.48	38%	102.7°
2027-04-13 Tue	62	—	unknown	02:45–05:05 (good, 2.33 h)	87.2° 08:50	7.42	50%	110.0°
2027-04-14 Wed	62	—	unknown	02:40–05:05 (good, 2.42 h)	87.2° 08:50	7.36	61%	116.2°
2027-04-15 Thu	61	—	unknown	02:35–05:00 (good, 2.42 h)	87.3° 08:45	7.31	72%	121.1°
2027-04-16 Fri	61	—	unknown	02:35–05:00 (good, 2.42 h)	87.3° 08:40	7.25	81%	123.9°
2027-04-17 Sat	57	—	unknown	02:35–05:00 (good, 2.42 h)	87.2° 08:35	7.19	89%	124.6°
2027-04-18 Sun	56	—	unknown	02:30–04:55 (good, 2.42 h)	87.2° 08:30	7.13	95%	122.9°
2027-04-19 Mon	55	—	unknown	02:30–04:55 (good, 2.42 h)	87.2° 08:30	7.08	99%	119.2°
2027-04-20 Tue	53	—	unknown	02:25–04:55 (good, 2.5 h)	87.3° 08:25	7.02	100%	114.0°
2027-04-21 Wed	50	—	unknown	02:25–04:50 (good, 2.42 h)	87.3° 08:20	6.96	99%	107.8°
2027-04-22 Thu	47	—	unknown	02:25–04:50 (good, 2.42 h)	87.2° 08:15	6.9	96%	101.0°
2027-04-23 Fri	45	—	unknown	02:25–04:45 (good, 2.33 h)	87.2° 08:15	6.84	90%	94.0°
2027-04-24 Sat	45	—	unknown	02:20–04:45 (good, 2.42 h)	87.2° 08:10	6.78	84%	87.0°
2027-04-25 Sun	46	—	unknown	02:15–04:45 (good, 2.5 h)	87.3° 08:05	6.73	76%	80.2°
2027-04-26 Mon	49	—	unknown	02:05–04:40 (good, 2.58 h)	87.3° 08:00	6.67	68%	73.8°
2027-04-27 Tue	57	—	unknown	01:40–04:40 (good, 3.0 h)	87.2° 07:55	6.61	59%	68.0°
2027-04-28 Wed	61	—	unknown	01:40–04:35 (good, 2.92 h)	87.2° 07:55	6.55	49%	63.0°
2027-04-29 Thu	67	—	unknown	01:35–04:35 (good, 3.0 h)	87.3° 07:50	6.49	40%	59.0°
2027-04-30 Fri	73	—	unknown	01:30–04:35 (good, 3.08 h)	87.3° 07:45	6.43	31%	56.3°
2027-05-01 Sat	77	—	unknown	01:25–04:30 (good, 3.08 h)	87.2° 07:40	6.38	22%	55.3°
2027-05-02 Sun	82	—	unknown	01:20–04:30 (good, 3.17 h)	87.2° 07:35	6.32	14%	56.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-03&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.