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 3C 273: 04-23 (93), 04-24 (93), 04-25 (93), 04-26 (93), 04-27 (93) — by astronomy; check the weather when the night is within four days.

2046-04-20astronomy score per night — click a bar for that night2046-05-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-04-20 Fri	28	—	unknown	21:50–03:35 (marginal, 5.75 h)	50.1° 23:55	6.99	100%	29.1°
2046-04-21 Sat	45	—	unknown	21:55–03:50 (marginal, 5.92 h)	50.1° 23:50	6.94	98%	43.2°
2046-04-22 Sun	92	—	unknown	21:55–00:40 (good, 2.75 h)	50.1° 23:50	6.88	94%	57.1°
2046-04-23 Mon	93	—	unknown	21:55–02:30 (good, 4.58 h)	50.1° 23:45	6.82	87%	70.7°
2046-04-24 Tue	93	—	unknown	22:00–03:10 (good, 5.17 h)	50.1° 23:40	6.76	79%	84.0°
2046-04-25 Wed	93	—	unknown	22:00–03:15 (good, 5.25 h)	50.1° 23:35	6.7	70%	96.8°
2046-04-26 Thu	93	—	unknown	22:00–03:15 (good, 5.25 h)	50.1° 23:30	6.64	60%	109.2°
2046-04-27 Fri	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:30	6.59	50%	121.3°
2046-04-28 Sat	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.53	41%	133.1°
2046-04-29 Sun	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.1° 23:20	6.47	32%	144.6°
2046-04-30 Mon	93	—	unknown	22:10–03:10 (good, 5.0 h)	50.1° 23:15	6.41	23%	155.8°
2046-05-01 Tue	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.35	16%	166.1°
2046-05-02 Wed	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.3	10%	171.0°
2046-05-03 Thu	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:05	6.24	5%	164.1°
2046-05-04 Fri	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:00	6.18	2%	153.2°
2046-05-05 Sat	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 22:55	6.12	0%	141.3°
2046-05-06 Sun	93	—	unknown	22:20–02:45 (good, 4.42 h)	50.1° 22:55	6.07	1%	129.1°
2046-05-07 Mon	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.1° 22:50	6.01	4%	116.5°
2046-05-08 Tue	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:45	5.95	8%	103.7°
2046-05-09 Wed	90	—	unknown	22:25–02:35 (good, 4.17 h)	50.1° 22:40	5.9	15%	90.6°
2046-05-10 Thu	86	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:35	5.84	24%	77.4°
2046-05-11 Fri	76	—	unknown	22:25–02:25 (good, 4.0 h)	50.1° 22:35	5.79	33%	63.9°
2046-05-12 Sat	59	—	unknown	22:30–02:20 (good, 3.83 h)	50.1° 22:30	5.73	44%	50.3°
2046-05-13 Sun	44	—	unknown	22:30–01:50 (good, 3.33 h)	50.1° 22:25	5.68	56%	36.7°
2046-05-14 Mon	31	—	unknown	22:30–02:40 (marginal, 4.17 h)	50.1° 22:20	5.62	67%	23.2°
2046-05-15 Tue	24	—	unknown	22:35–02:30 (marginal, 3.92 h)	50.1° 22:20	5.57	77%	11.4°
2046-05-16 Wed	19	—	unknown	22:35–02:15 (marginal, 3.67 h)	50.1° 22:15	5.52	86%	11.7°
2046-05-17 Thu	16	—	unknown	22:35–02:00 (marginal, 3.42 h)	50.1° 22:10	5.46	93%	23.7°
2046-05-18 Fri	19	—	unknown	22:40–01:55 (marginal, 3.25 h)	50.1° 22:05	5.41	98%	37.4°
2046-05-19 Sat	26	—	unknown	22:40–02:00 (marginal, 3.33 h)	50.1° 22:00	5.36	100%	51.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-04-20&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.