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: 01-17 (93), 01-18 (93), 01-19 (93), 01-20 (93), 01-21 (93) — by astronomy; check the weather when the night is within four days.

2042-01-10astronomy score per night — click a bar for that night2042-02-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-01-10 Fri	19	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.1° 05:30	11.32	81%	23.3°
2042-01-11 Sat	26	—	unknown	01:30–06:10 (marginal, 4.67 h)	50.1° 05:25	11.3	73%	11.6°
2042-01-12 Sun	35	—	unknown	01:15–06:10 (marginal, 4.92 h)	50.1° 05:20	11.28	64%	2.6°
2042-01-13 Mon	47	—	unknown	04:30–04:40 (good, 0.17 h)	50.1° 05:15	11.26	55%	12.6°
2042-01-14 Tue	61	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:15	11.24	46%	24.5°
2042-01-15 Wed	84	—	unknown	01:25–06:10 (good, 4.75 h)	50.1° 05:10	11.22	36%	36.6°
2042-01-16 Thu	90	—	unknown	01:20–06:10 (good, 4.83 h)	50.1° 05:05	11.2	27%	49.1°
2042-01-17 Fri	93	—	unknown	01:15–06:10 (good, 4.92 h)	50.1° 05:00	11.18	18%	62.0°
2042-01-18 Sat	93	—	unknown	01:10–06:10 (good, 5.0 h)	50.1° 05:00	11.15	11%	75.2°
2042-01-19 Sun	93	—	unknown	01:05–06:10 (good, 5.08 h)	50.1° 04:55	11.13	5%	88.9°
2042-01-20 Mon	93	—	unknown	01:05–06:10 (good, 5.08 h)	50.1° 04:50	11.1	1%	103.0°
2042-01-21 Tue	93	—	unknown	01:00–06:05 (good, 5.08 h)	50.1° 04:45	11.08	0%	117.4°
2042-01-22 Wed	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.1° 04:40	11.05	2%	132.1°
2042-01-23 Thu	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.1° 04:40	11.03	6%	146.8°
2042-01-24 Fri	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.1° 04:35	11.0	13%	161.5°
2042-01-25 Sat	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.1° 04:30	10.97	22%	175.5°
2042-01-26 Sun	93	—	unknown	00:40–06:05 (good, 5.42 h)	50.1° 04:25	10.94	32%	168.9°
2042-01-27 Mon	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.1° 04:20	10.91	43%	155.0°
2042-01-28 Tue	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.1° 04:20	10.88	55%	141.2°
2042-01-29 Wed	93	—	unknown	00:35–06:00 (good, 5.42 h)	50.1° 04:15	10.85	65%	127.6°
2042-01-30 Thu	93	—	unknown	00:35–06:00 (good, 5.42 h)	50.1° 04:10	10.82	75%	114.3°
2042-01-31 Fri	92	—	unknown	00:45–06:00 (good, 5.25 h)	50.1° 04:05	10.79	83%	101.3°
2042-02-01 Sat	74	—	unknown	01:35–06:00 (good, 4.42 h)	50.1° 04:05	10.75	90%	88.4°
2042-02-02 Sun	59	—	unknown	03:25–06:00 (good, 2.58 h)	50.1° 04:00	10.72	95%	75.8°
2042-02-03 Mon	44	—	unknown	00:15–06:00 (marginal, 5.75 h)	50.1° 03:55	10.69	98%	63.3°
2042-02-04 Tue	30	—	unknown	00:40–05:55 (marginal, 5.25 h)	50.1° 03:50	10.65	100%	51.0°
2042-02-05 Wed	21	—	unknown	02:55–05:55 (marginal, 3.0 h)	50.1° 03:45	10.62	99%	38.9°
2042-02-06 Thu	17	—	unknown	04:10–05:55 (marginal, 1.75 h)	50.1° 03:45	10.58	97%	26.9°
2042-02-07 Fri	19	—	unknown	02:10–05:55 (marginal, 3.75 h)	50.1° 03:40	10.55	93%	15.1°
2042-02-08 Sat	24	—	unknown	23:50–05:55 (marginal, 6.08 h)	50.1° 03:35	10.51	87%	4.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-01-10&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.