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 V1057 Cyg: 05-16 (98), 05-14 (97), 05-15 (97), 05-13 (96), 05-11 (94) — by astronomy; check the weather when the night is within four days.

2040-04-17astronomy score per night — click a bar for that night2040-05-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-04-17 Tue	66	—	unknown	02:20–04:55 (good, 2.58 h)	87.3° 08:35	7.14	35%	103.5°
2040-04-18 Wed	67	—	unknown	02:20–04:55 (good, 2.58 h)	87.3° 08:30	7.08	44%	108.1°
2040-04-19 Thu	67	—	unknown	02:20–04:55 (good, 2.58 h)	87.3° 08:25	7.03	54%	111.9°
2040-04-20 Fri	67	—	unknown	02:15–04:50 (good, 2.58 h)	87.3° 08:20	6.97	63%	114.9°
2040-04-21 Sat	66	—	unknown	02:15–04:50 (good, 2.58 h)	87.2° 08:20	6.91	72%	116.8°
2040-04-22 Sun	60	—	unknown	02:10–04:45 (good, 2.58 h)	87.3° 08:15	6.85	81%	117.4°
2040-04-23 Mon	59	—	unknown	02:10–04:45 (good, 2.58 h)	87.3° 08:10	6.79	88%	116.6°
2040-04-24 Tue	57	—	unknown	02:10–04:45 (good, 2.58 h)	87.3° 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%	110.5°
2040-04-26 Thu	51	—	unknown	02:10–04:40 (good, 2.5 h)	87.3° 08:00	6.62	100%	105.5°
2040-04-27 Fri	48	—	unknown	02:10–04:40 (good, 2.5 h)	87.3° 07:55	6.56	99%	99.6°
2040-04-28 Sat	45	—	unknown	02:05–04:35 (good, 2.5 h)	87.3° 07:50	6.5	96%	93.2°
2040-04-29 Sun	46	—	unknown	02:00–04:35 (good, 2.58 h)	87.3° 07:45	6.44	90%	86.5°
2040-04-30 Mon	46	—	unknown	01:55–04:30 (good, 2.58 h)	87.2° 07:40	6.39	81%	80.0°
2040-05-01 Tue	52	—	unknown	01:25–04:30 (good, 3.08 h)	87.3° 07:40	6.33	71%	74.1°
2040-05-02 Wed	64	—	unknown	01:20–04:30 (good, 3.17 h)	87.3° 07:35	6.27	60%	69.1°
2040-05-03 Thu	72	—	unknown	01:15–04:25 (good, 3.17 h)	87.3° 07:30	6.21	49%	65.4°
2040-05-04 Fri	79	—	unknown	01:10–04:25 (good, 3.25 h)	87.3° 07:25	6.16	38%	63.2°
2040-05-05 Sat	85	—	unknown	01:10–04:25 (good, 3.25 h)	87.2° 07:25	6.1	27%	62.7°
2040-05-06 Sun	86	—	unknown	01:05–04:20 (good, 3.25 h)	87.3° 07:20	6.04	18%	63.8°
2040-05-07 Mon	88	—	unknown	01:00–04:20 (good, 3.33 h)	87.3° 07:15	5.98	11%	66.4°
2040-05-08 Tue	90	—	unknown	00:55–04:20 (good, 3.42 h)	87.3° 07:10	5.93	5%	70.2°
2040-05-09 Wed	91	—	unknown	00:50–04:15 (good, 3.42 h)	87.3° 07:05	5.87	2%	74.8°
2040-05-10 Thu	91	—	unknown	00:50–04:15 (good, 3.42 h)	87.3° 07:05	5.82	0%	80.1°
2040-05-11 Fri	94	—	unknown	00:45–04:15 (good, 3.5 h)	87.3° 07:00	5.76	1%	85.6°
2040-05-12 Sat	94	—	unknown	00:40–04:10 (good, 3.5 h)	87.3° 06:55	5.71	3%	91.2°
2040-05-13 Sun	96	—	unknown	00:35–04:10 (good, 3.58 h)	87.3° 06:50	5.65	7%	96.7°
2040-05-14 Mon	97	—	unknown	00:30–04:10 (good, 3.67 h)	87.2° 06:45	5.6	13%	101.9°
2040-05-15 Tue	97	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:45	5.55	20%	106.6°
2040-05-16 Wed	98	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:40	5.49	28%	110.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-04-17&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.