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: 04-16 (67), 04-18 (67), 04-19 (67), 04-20 (67), 04-21 (67) — by astronomy; check the weather when the night is within four days.

2040-03-31astronomy score per night — click a bar for that night2040-04-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-03-31 Sat	33	—	unknown	03:50–05:30 (good, 1.67 h)	87.2° 09:40	8.1	87%	97.4°
2040-04-01 Sun	34	—	unknown	03:45–05:30 (good, 1.75 h)	87.2° 09:35	8.05	79%	91.0°
2040-04-02 Mon	35	—	unknown	03:40–05:25 (good, 1.75 h)	87.2° 09:30	7.99	68%	84.6°
2040-04-03 Tue	38	—	unknown	03:30–05:25 (good, 1.92 h)	87.2° 09:30	7.94	57%	78.4°
2040-04-04 Wed	44	—	unknown	03:10–05:20 (good, 2.17 h)	87.2° 09:25	7.88	46%	72.7°
2040-04-05 Thu	51	—	unknown	03:05–05:20 (good, 2.25 h)	87.2° 09:20	7.83	35%	68.1°
2040-04-06 Fri	57	—	unknown	03:00–05:20 (good, 2.33 h)	87.2° 09:15	7.77	24%	64.7°
2040-04-07 Sat	57	—	unknown	03:00–05:15 (good, 2.25 h)	87.2° 09:15	7.72	16%	62.9°
2040-04-08 Sun	59	—	unknown	02:55–05:15 (good, 2.33 h)	87.2° 09:10	7.66	8%	62.8°
2040-04-09 Mon	60	—	unknown	02:50–05:15 (good, 2.42 h)	87.2° 09:05	7.6	3%	64.3°
2040-04-10 Tue	60	—	unknown	02:45–05:10 (good, 2.42 h)	87.2° 09:00	7.55	1%	67.4°
2040-04-11 Wed	62	—	unknown	02:40–05:10 (good, 2.5 h)	87.2° 08:55	7.49	0%	71.5°
2040-04-12 Thu	62	—	unknown	02:40–05:05 (good, 2.42 h)	87.2° 08:55	7.43	2%	76.4°
2040-04-13 Fri	63	—	unknown	02:35–05:05 (good, 2.5 h)	87.2° 08:50	7.37	6%	81.8°
2040-04-14 Sat	65	—	unknown	02:30–05:05 (good, 2.58 h)	87.2° 08:45	7.32	11%	87.4°
2040-04-15 Sun	65	—	unknown	02:25–05:00 (good, 2.58 h)	87.2° 08:40	7.26	18%	93.0°
2040-04-16 Mon	67	—	unknown	02:20–05:00 (good, 2.67 h)	87.2° 08:35	7.2	26%	98.4°
2040-04-17 Tue	66	—	unknown	02:20–04:55 (good, 2.58 h)	87.2° 08:35	7.14	35%	103.5°
2040-04-18 Wed	67	—	unknown	02:20–04:55 (good, 2.58 h)	87.2° 08:30	7.08	44%	108.0°
2040-04-19 Thu	67	—	unknown	02:20–04:55 (good, 2.58 h)	87.2° 08:25	7.03	54%	111.9°
2040-04-20 Fri	67	—	unknown	02:15–04:50 (good, 2.58 h)	87.2° 08:20	6.97	63%	114.8°
2040-04-21 Sat	67	—	unknown	02:15–04:50 (good, 2.58 h)	87.2° 08:20	6.91	72%	116.7°
2040-04-22 Sun	60	—	unknown	02:10–04:45 (good, 2.58 h)	87.2° 08:15	6.85	81%	117.3°
2040-04-23 Mon	59	—	unknown	02:10–04:45 (good, 2.58 h)	87.2° 08:10	6.79	88%	116.5°
2040-04-24 Tue	57	—	unknown	02:10–04:45 (good, 2.58 h)	87.2° 08:05	6.74	94%	114.2°
2040-04-25 Wed	54	—	unknown	02:10–04:40 (good, 2.5 h)	87.2° 08:00	6.68	98%	110.4°
2040-04-26 Thu	51	—	unknown	02:10–04:40 (good, 2.5 h)	87.2° 08:00	6.62	100%	105.5°
2040-04-27 Fri	48	—	unknown	02:10–04:40 (good, 2.5 h)	87.2° 07:55	6.56	99%	99.6°
2040-04-28 Sat	46	—	unknown	02:05–04:35 (good, 2.5 h)	87.2° 07:50	6.5	96%	93.2°
2040-04-29 Sun	46	—	unknown	02:00–04:35 (good, 2.58 h)	87.2° 07:45	6.44	90%	86.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-03-31&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.