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 HD 189733: 04-27 (69), 04-29 (69), 04-24 (68), 04-26 (68), 04-28 (68) — by astronomy; check the weather when the night is within four days.

2042-04-01astronomy score per night — click a bar for that night2042-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-04-01 Tue	40	—	unknown	03:50–05:30 (good, 1.67 h)	71.1° 08:40	8.08	88%	128.7°
2042-04-02 Wed	38	—	unknown	03:45–05:25 (good, 1.67 h)	71.1° 08:35	8.02	94%	124.0°
2042-04-03 Thu	38	—	unknown	03:45–05:25 (good, 1.67 h)	71.1° 08:35	7.97	98%	117.9°
2042-04-04 Fri	36	—	unknown	03:45–05:25 (good, 1.67 h)	71.1° 08:30	7.91	100%	111.0°
2042-04-05 Sat	32	—	unknown	03:45–05:20 (good, 1.58 h)	71.1° 08:25	7.85	100%	103.4°
2042-04-06 Sun	30	—	unknown	03:45–05:20 (good, 1.58 h)	71.1° 08:20	7.8	98%	95.5°
2042-04-07 Mon	28	—	unknown	04:05–05:15 (good, 1.17 h)	71.1° 08:15	7.74	95%	87.3°
2042-04-08 Tue	27	—	unknown	04:15–05:15 (good, 1.0 h)	71.1° 08:15	7.69	90%	79.2°
2042-04-09 Wed	27	—	unknown	04:10–05:15 (good, 1.08 h)	71.1° 08:10	7.63	83%	71.2°
2042-04-10 Thu	28	—	unknown	03:50–05:10 (good, 1.33 h)	71.1° 08:05	7.57	75%	63.7°
2042-04-11 Fri	31	—	unknown	03:25–05:10 (good, 1.75 h)	71.1° 08:00	7.52	66%	56.9°
2042-04-12 Sat	37	—	unknown	02:55–05:10 (good, 2.25 h)	71.1° 08:00	7.46	56%	51.5°
2042-04-13 Sun	47	—	unknown	02:50–05:05 (good, 2.25 h)	71.1° 07:55	7.4	45%	48.1°
2042-04-14 Mon	54	—	unknown	02:50–05:05 (good, 2.25 h)	71.1° 07:50	7.34	34%	47.5°
2042-04-15 Tue	58	—	unknown	02:45–05:00 (good, 2.25 h)	71.1° 07:45	7.29	24%	49.9°
2042-04-16 Wed	59	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:40	7.23	14%	55.2°
2042-04-17 Thu	61	—	unknown	02:35–05:00 (good, 2.42 h)	71.1° 07:40	7.17	7%	62.8°
2042-04-18 Fri	62	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.11	2%	71.8°
2042-04-19 Sat	63	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:30	7.05	0%	81.7°
2042-04-20 Sun	63	—	unknown	02:25–04:50 (good, 2.42 h)	71.1° 07:25	7.0	1%	91.9°
2042-04-21 Mon	65	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:20	6.94	5%	101.8°
2042-04-22 Tue	66	—	unknown	02:15–04:50 (good, 2.58 h)	71.1° 07:20	6.88	11%	111.0°
2042-04-23 Wed	66	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:15	6.82	19%	119.1°
2042-04-24 Thu	68	—	unknown	02:10–04:45 (good, 2.58 h)	71.1° 07:10	6.76	28%	125.6°
2042-04-25 Fri	67	—	unknown	02:10–04:40 (good, 2.5 h)	71.1° 07:05	6.71	38%	130.2°
2042-04-26 Sat	68	—	unknown	02:05–04:40 (good, 2.58 h)	71.1° 07:00	6.65	48%	132.5°
2042-04-27 Sun	69	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.59	58%	132.2°
2042-04-28 Mon	68	—	unknown	02:00–04:35 (good, 2.58 h)	71.1° 06:55	6.53	68%	129.7°
2042-04-29 Tue	69	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:50	6.47	76%	125.4°
2042-04-30 Wed	64	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:45	6.41	84%	119.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-04-01&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.