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: 01-31 (93), 02-01 (93), 02-02 (93), 02-03 (93), 02-04 (93) — by astronomy; check the weather when the night is within four days.

2027-01-30astronomy score per night — click a bar for that night2027-02-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-01-30 Sat	92	—	unknown	00:25–06:00 (good, 5.58 h)	50.2° 04:10	10.83	36%	52.7°
2027-01-31 Sun	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.2° 04:05	10.8	27%	64.5°
2027-02-01 Mon	93	—	unknown	00:15–06:00 (good, 5.75 h)	50.2° 04:05	10.77	19%	76.2°
2027-02-02 Tue	93	—	unknown	00:10–06:00 (good, 5.83 h)	50.2° 04:00	10.73	12%	87.9°
2027-02-03 Wed	93	—	unknown	00:10–06:00 (good, 5.83 h)	50.2° 03:55	10.7	7%	99.6°
2027-02-04 Thu	93	—	unknown	00:05–05:55 (good, 5.83 h)	50.2° 03:50	10.66	3%	111.3°
2027-02-05 Fri	93	—	unknown	00:00–05:55 (good, 5.92 h)	50.2° 03:50	10.63	0%	123.1°
2027-02-06 Sat	93	—	unknown	23:55–05:55 (good, 6.0 h)	50.2° 03:45	10.59	0%	134.9°
2027-02-07 Sun	93	—	unknown	23:55–05:55 (good, 6.0 h)	50.2° 03:40	10.56	2%	146.7°
2027-02-08 Mon	93	—	unknown	23:50–05:55 (good, 6.08 h)	50.2° 03:35	10.52	5%	158.3°
2027-02-09 Tue	93	—	unknown	23:45–05:50 (good, 6.08 h)	50.2° 03:30	10.49	10%	168.6°
2027-02-10 Wed	93	—	unknown	23:40–05:50 (good, 6.17 h)	50.2° 03:30	10.45	17%	170.1°
2027-02-11 Thu	93	—	unknown	23:35–05:50 (good, 6.25 h)	50.2° 03:25	10.41	25%	160.1°
2027-02-12 Fri	93	—	unknown	23:35–05:50 (good, 6.25 h)	50.2° 03:20	10.37	35%	147.8°
2027-02-13 Sat	93	—	unknown	23:35–05:45 (good, 6.17 h)	50.2° 03:15	10.33	46%	134.8°
2027-02-14 Sun	93	—	unknown	23:30–05:45 (good, 6.25 h)	50.2° 03:10	10.3	57%	121.3°
2027-02-15 Mon	93	—	unknown	23:35–05:45 (good, 6.17 h)	50.2° 03:10	10.26	68%	107.4°
2027-02-16 Tue	90	—	unknown	23:45–05:45 (good, 6.0 h)	50.2° 03:05	10.22	78%	93.1°
2027-02-17 Wed	85	—	unknown	01:25–05:40 (good, 4.25 h)	50.2° 03:00	10.18	87%	78.6°
2027-02-18 Thu	55	—	unknown	05:10–05:40 (good, 0.5 h)	50.2° 02:55	10.13	94%	63.9°
2027-02-19 Fri	37	—	unknown	23:35–05:40 (marginal, 6.08 h)	50.2° 02:55	10.09	98%	49.2°
2027-02-20 Sat	24	—	unknown	02:20–05:40 (marginal, 3.33 h)	50.2° 02:50	10.05	100%	34.7°
2027-02-21 Sun	21	—	unknown	02:50–05:35 (marginal, 2.75 h)	50.2° 02:45	10.01	99%	20.9°
2027-02-22 Mon	24	—	unknown	23:05–05:35 (marginal, 6.5 h)	50.2° 02:40	9.97	95%	9.8°
2027-02-23 Tue	32	—	unknown	22:40–05:35 (marginal, 6.92 h)	50.2° 02:35	9.92	89%	12.4°
2027-02-24 Wed	49	—	unknown	22:20–05:35 (marginal, 7.25 h)	50.2° 02:35	9.88	81%	24.0°
2027-02-25 Thu	84	—	unknown	22:40–02:00 (good, 3.33 h)	50.2° 02:30	9.84	72%	36.4°
2027-02-26 Fri	90	—	unknown	22:40–05:05 (good, 6.42 h)	50.2° 02:25	9.79	62%	48.7°
2027-02-27 Sat	93	—	unknown	22:35–05:30 (good, 6.92 h)	50.2° 02:20	9.75	53%	60.8°
2027-02-28 Sun	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.2° 02:15	9.7	43%	72.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-30&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.