Night Reports 2023

In the tables below, Observing, Weather and Technical refer to time spent observing, time lost to bad weather, and time lost because of technical problems. Note that Observing includes time spent on calibration observations and, occasionally, scheduled on-sky test observations; Technical does not include scheduled downtime (e.g. for planned engineering work).

The Night Duty Officer estimates whether the night was photometric or non-photometric (spectroscopic) based on satellite imagery and SkyCam data obtained through the night. This is a qualitative assessment only and may not always be entirely accurate. IT IS POSSIBLE THAT, ON OCCASION, OBSERVATIONS REQUIRING PHOTOMETRIC CONDITIONS ARE ACQUIRED IN NON-PHOTOMETRIC CONDITIONS. Users should check the quality of their data carefully. Good, average and poor seeing refers to inferred zenith seeing of < 1.0 arcsec, 1.0-2.0 arcsec, and > 2.0 arcsec, respectively. Calima refers to a warm wind that occasionally blows over from the Sahara and brings a lot of fine dust forcing a shutdown to protect the optics.

SKYCAM MOVIES AND ATMOSPHERIC TRANSMISSION

Below we also provide links to Movies constructed from a sequence of optical images obtained with either SkyCam-A (covering the whole sky), SkyCam-T (now showing a 9 degree field centred on each target; was 21 deg pre-21 Oct) or SkyCam-Z (1 degree field). Images are obtained every minute or so throughout the entire night. These movies can usually be used to establish, qualitatively at least, how clear or cloudy a given night was. On bright nights (i.e. when the moon is up), the smaller-field camera's T and Z are often more useful than the full-sky camera A. Additional movies and still images are available from the Skycam Archive. Plots of SkyCamZ Zero Point data are also provided. Zero points here are defined with respect to APASS 10 < r < 13 with no colour term. These indicate to first order periods of thin or thick cloud. A clear night usually results in a flat distribution of ZP values, while thick cloud causes a dip in the ZP level. 'A', 'T' and 'Z' in the SkyCam columns refer to the camera from which the data were acquired.

January 2023

Date	Hours Used			Comment	SkyCam
Date	Observing	Weather	Technical	Comment	ZP Plot	Movie
25 Jan	9.2	1.4	0.0	Non-photometric with average/poor seeing. High cloud in the middle of the night.	T	A T -
24 Jan	10.6	0.0	0.0	Photometric, with good/average seeing.	T	A T -
23 Jan	10.6	0.0	0.0	Photometric, with average/poor seeing.	T	A T -
22 Jan	0.0	10.6	0.0	High humidity.	T	A T -
21 Jan	3.6	7.0	0.0	Non-photometic with average/poor seeing. High humidity.	T	A T -
20 Jan	9.7	1.0	0.0	Photometric with average/poor seeing. Brief closure for high humidity.	T	A T -
19 Jan	0.8	9.9	0.0	High humidity. Non-photometric with poor seeing.	T	A T -
18 Jan	2.2	8.5	0.0	High humidity. Non-photometric with average seeing.	T	A T -
17 Jan	10.7	0.0	0.0	Photometric with average seeing.	T	A T -
16 Jan	5.3	5.4	0.0	Non-photometric with average/poor seeing. High humidity in second half of night.	T	A T -
15 Jan	2.2	2.0	6.5	Non-photometric, seeing good-average.	T	A T -
14 Jan	9.3	1.4	0.0	Non-photometric, seeing good-average.	T	A T -
13 Jan	10.7	0.0	0.0	Non-photometric, average-bad seeing.	T	A T -
12 Jan	10.7	0.0	0.0	Non-photometric, average-bad seeing.	T	A T -
11 Jan	0.0	10.7	0.0	High humidity.	T	A T -
10 Jan	2.0	8.8	0.0	High humidity. Bad seeing in non-photometric conditions.	T	A T -
9 Jan	0.0	0.0	10.8	IO:O warming up.	T	A T -
8 Jan	10.8	0.0	0.0	Photometric, average/poor seeing.	T	A T -
7 Jan	10.8	0.0	0.0	Photometric, good/average seeing.	T	A T -
6 Jan	10.8	0.0	0.0	Photometric, full range of seeing from good through to poor.	T	A T -
5 Jan	10.8	0.0	0.0	Photometric, full range of seeing from good through to poor.	T	A T -
4 Jan	7.0	3.8	0.0	Set to non-photometric, sky photometric; good-average seeing. High humidity at start and middle of night.	T	A T -
3 Jan	9.1	1.7	0.0	Photometric and set as such for second half of night. Average to good seeing. High humidity at start of night and in early morning.	T	A T -
2 Jan	0.0	10.8	0.0	High humidity all night plus lightning risk.	-	- - -
1 Jan	0.0	10.9	0.0	High humidity all night.	-	- - -