Sky brightness (SQM-L) readings

posted: 1665 days ago, on Saturday, 2013 May 04 at 02:15
tags: astronomy, observing report, light pollution, SQM.

A log of sky brightness readings, made with SQM-L meters, at various places in South Africa. The measured values in the table below are in magnitudes per square arcsecond.

Astronomer Brian Skiff notes that it is widely accepted that the zenithal sky brightness of a site completely free from man-made light pollution, and at a time when solar activity is a minimum, is 22.0 magnitudes per square arcsecond. He considers a "true-dark" site as one where the sky brightness is less than half a magnitude brighter than the natural background glow, i.e. 21.5-mag per square arcsecond.

SQM-L readings

PlaceDate (SAST)░CNotesOCIndividual readingsmeansigma
 
 
Hakos Observatory, Namibia2012 Dec 11, 22:2118----AS21.97, 21.97, 22.03, 21.93, 21.93, 21.92, 21.93, 21.93, 21.93, 21.9521.950.03
Hakos Observatory, Namibia2012 Dec 09, 23:0021----AS21.89, 21.94, 21.87, 21.88, 21.90, 21.91, 21.92, 21.92, 21.91, 22.0021.910.04
Hakos Observatory, Namibia2012 Dec 10, 23:3013----AS21.83, 21.78, 21.84, 21.82, 21.82, 21.81, 21.81, 21.80, 21.81, 21.7521.810.03
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Aug 18, 00:354at zenithAS21.87, 21.74, 21.81, 21.74, 21.76, 21.81, 21.78, 21.79, 21.79, 21.8421.790.04
Hakos Observatory, Namibia2012 Dec 15, 23:4315----AS21.86, 21.80, 21.76, 21.74, 21.73, 21.72, 21.72, 21.74, 21.73, 21.7621.760.04
Oestervanger [33:57:15, 19:40:11], 310m2010 Dec 03, 01:4518----EF----21.76----
Karoo Star Party, Britstown2010 Aug 07, 02:255----AS21.77, 21.72, 21.72, 21.73, 21.74, 21.74, 21.74, 21.78, 21.74, 21.7421.740.02
Sutherland [32:23:37, 20:39:41], 1456m2010 Dec 11, 23:3018----EF----21.74----
Sutherland, Middelfontein2010 Apr 12, 22:5514----AS21.76, 21.80, 21.72, 21.70, 21.70, 21.70, 21.70, 21.73, 21.81, 21.7021.730.04
Sutherland, Sterland2010 Apr 12, 23:1515----AS21.83, 21.79, 21.72, 21.72, 21.72, 21.71, 21.71, 21.71, 21.71, 21.7121.730.04
Bonnievale, Night Sky Caravan Park2011 Feb 06, 01:3520----AS21.69, 21.72, 21.74, 21.72, 21.72, 21.7, 21.71, 21.71, 21.75, 21.7521.720.02
Karoo Star Party, Britstown2010 Aug 08, 03:407----AS21.75, 21.72, 21.72, 21.71, 21.71, 21.71, 21.71, 21.70, 21.70, 21.6921.710.02
Sutherland, SAAO2010 Apr 12, 23:4616----AS21.69, 21.72, 21.70, 21.68, 21.68, 21.68, 21.70, 21.70, 21.65, 21.6821.690.02
Sutherland, Sterland2010 Jun 10, 22:317---AS21.71, 21.64, 21.63, 21.61, 21.59, 21.69, 21.77, 21.76, 21.68, 21.6921.680.06
Hakos Observatory, Namibia2012 Dec 15, 00:2315----AS21.50, 21.58, 21.65, 21.70, 21.69, 21.69, 21.69, 21.69, 21.69, 21.6921.660.07
Bonnievale, Night Sky Caravan Park2012 Sep 15, 22:0012----AS21.6, 21.65, 21.65, 21.6, 21.59, 21.58, 21.60, 21.66, 21.61, 21.6121.620.03
Hakos Observatory, Namibia2012 Dec 14, 04:2716----AS21.61, 21.68, 21.55, 21.62, 21.59, 21.58, 21.59, 21.57, 21.61, 21.6121.600.04
Sutherland, Sterland roadside2010 Apr 07, 22:35-------AS21.61, 21.61, 21.59, 21.46, 21.46, 21.58, 21.61, 21.6121.570.07
Hakos Observatory, Namibia2012 Dec 12, 03:0017----AS21.43, 21.50, 21.51, 21.46, 21.50, 21.52, 21.53, 21.51, 21.54, 21.5421.500.04
Impangele (Hex) [33:27:36, 19:42:28], 642m2010 Dec 10, 00:0019----EF----21.49----
Blesfontein [32:28:04.5,20:26:11] 1421-m2010 Apr 09, 20:3018100% cloudAS21.32, 21.49, 21.5, 21.72, 21.64, 21.69, 21.52, 21.46, 21.28, 21.2321.490.17
Night Sky [34:00:46, 19:49:57], 210m2011 Feb 04, 01:0522----EF----21.45----
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Jun 19, 23:00-------EF----21.44----
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Dec 17, 23:00-------EF----21.44----
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Mar 16, 00:3026----EF21.38, 21.46, 21.31, 21.56, 21.41, 21.43, 21.42, 21.44, 21.42, 21.4221.430.06
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Jun 20, 20:00-------EF----21.41----
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Apr 13, 01:0212----AS21.41, 21.41, 21.42, 21.43, 21.42, 21.39, 21.37, 21.41, 21.36, 21.4021.400.02
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Apr 13, 20:4919----EF----21.38----
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Apr 15, 00:4517----EF----21.38----
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Jun 20, 23:00-------EF----21.38----
Hakos Observatory, Namibia2102 Dec 08, 01:2521----AS21.33, 21.38, 21.39, 21.38, 21.36, 21.34, 21.32, 21.36, 21.32, 21.3621.350.03
Aquila Game Park [33:21:09, 19:50:08], 720m2011 Apr 09, 23:5022----EF----21.32----
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Aug 18, 00:355aimed at M7AS21.33, 21.33, 21.34, 21.32, 21.33, 21.31, 21.26, 21.33, 21.26, 21.2921.310.03
Leeuwenbosfontein2011 Apr 30, 00:016----AS21.31, 21.29, 21.3, 21.27, 21.32, 21.29, 21.29, 21.29, 21.27, 21.3021.290.02
Leeuwenbosfontein2011 May 01, 00:156----AS21.33, 21.34, 21.29, 21.27, 21.29, 21.27, 21.27, 21.26, 21.27, 21.2721.290.03
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Apr 14, 00:0514----EF----21.29----
Sutherland, Sterland2010 Apr 09, 21:0015----AS21.18, 21.21, 21.21, 21.23, 21.23, 21.23, 21.24, 21.23, 21.32, 21.3021.240.04
Bergwater Lodge, Pietersfontein Dam, Montagu2013 Apr 12, 02:0017----EF----21.23----
Bergwater Lodge, Pietersfontein Dam, Montagu2012 Jun 19, 20:00-------EF----21.21----
Karoo Star Party, Britstown2010 Aug 06, 22:359----AS21.22, 21.19, 21.20, 21.20, 21.22, 21.18, 21.20, 21.17, 21.20, 21.2021.200.02
Merweville2010 May 01, 19:3022----AS21.15, 21.15, 21.15, 21.15, 21.19, 21.15, 21.13, 21.15, 21.01, 21.1521.140.05
Cape Town, Paardeberg [33:34:25S, 18:51:15E]2010 Jun 05, 20:4614---AS21.13, 21.13, 21.13, 21.13, 21.13, 21.13, 21.13, 21.12, 21.12, 21.1521.130.01
Cape Town, Paardeberg [33:34:25S, 18:51:15E]2010 Jun 06, 01:2011---AS21.13, 21.13, 21.13, 21.13, 21.13, 21.13, 21.14, 21.12, 21.12, 21.1221.130.01
Springbok [29:40:11S, 17:53:07E]2012 Dec 19, 23:5325----AS20.69, 20.67, 20.71, 20.64, 20.63, 20.63, 20.59, 20.70, 20.69, 20.6920.660.04
Ostrich Ranch, N7, Cape Town2013 April 30, 21:5816----AS20.27, 20.24, 20.25, 20.25, 20.29, 20.30, 20.27, 20.27, 20.25, 20.2820.270.02
Sutherland, Kambro2010 Apr 07, 22:3019----AS20.04, 20.26, 20.23, 20.18, 20.20, 20.34, 20.30, 20.25, 20.27, 20.3420.240.09
Sutherland, Kambro2010 Apr 09, 00:0116----AS20.33, 20.30, 20.11, 20.05, 20.44, 20.18, 20.2120.230.13
Merweville2010 Apr 30, 19:5019----AS20.01, 20.01, 20.01, 20.03, 19.98, 19.95, 20.01, 19.97, 20.01, 19.9219.990.03
Somerset West suburb [34:04:06S, 18:50:03E]2010 May 12, 21:1218----AS19.74, 19.71, 19.71, 19.74, 19.74, 19.75, 19.75, 19.72, 19.75, 19.7219.730.02
Eerste Steen (Melkbos) [33:46:38, 18:26:54], 6m2011 Mar 24, 20:3020----EF----19.42----
Breede Valley [33:42:07S, 19:21:29E]2010 Apr 24, 20:0618MoonAS19.36, 19.37, 19.43, 19.40, 19.39, 19.38, 19.38, 19.39, 19.42, 19.4019.390.02
Simondium [33:48:20S, 18:57:02E]2010 Apr 24, 23:1916MoonAS19.20, 19.19, 19.25, 19.21, 19.19, 19.24, 19.18, 19.21, 19.20, 19.2419.210.02
Camerton (UK) [51:19:01, 02:02:27], 75m2011 Jul 03, 23:3519----EF----18.93----
Stellenbosch, Die Boord suburb2010 Apr 24, 23:5918MoonAS18.65, 18.58, 18.59, 18.64, 18.62, 18.67, 18.77, 18.74, 18.69, 18.7118.670.06
Johannesburg, ScopeX War Museum2010 Apr 17, 22:00-------AS18.12, 18.02, 18.10, 18.14, 18.16, 18.17, 18.18, 18.17, 18.12, 18.1718.140.05
Brackenfell [33:52:52, 18:40:45], 99m2010 Nov 16, 21:5026----EF----17.9----
Wanstead (UK) [51:35:01, 00:02:04], 16m2011 Jul 02, 23:1019----EF----17.76----
V°gsli (Norway) [59:44:06, 07:33:08], 1500m2011 Jun 22, 00:1514----EF----13.31----
Oslo (Norway) [59:55:16, 10:43:21], 25m2011 Jun 06, 00:1524----EF----13.00----
Ulefoss (Norway) [59:16:37, 09:16:01], 60m2011 Jun 21, 00:1520----EF----12.25----
 

Key: Column 2: Date and time in SAST (or local time). Column 5: Observer Code [AS=Auke Slotegraaf, EF=Ed Foster]

Further reading

Birriel, J. et al. (2010) Documenting Local Night Sky Brightness Using Sky Quality Meters: An Interdisciplinary College Capstone Project and a First Step Toward Reducing Light Pollution. JAAVSO, 38, 132-138. [2010JAVSO..38..132B]

nothing more to see. please move along.