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Congratulations to B Espey, PhDa,b and J McCauley, MSca for the publication of their paper:

Initial Irish light pollution measurements and a new Sky Quality Meter-based data logger

in Lighting Research and Technology, on February 2014 vol. 46 no. 1 67-77

From the Abstract:
In the Celtic Tiger years, Ireland underwent an explosive growth in housing and an increase in light pollution, nationally. We outline work undertaken towards the first ever ground-based survey of light pollution in the island of Ireland and illustrate this with some representative data taken between 2009 and the present. The aim of our work is to establish a database to serve as a reference to monitor future changes, to compare with in-orbit measurements, to study the potential impact on the environment and to permit the calculation of the effects of future changes in lighting usage and patterns. We also report the development of a microcontroller-based data-logging instrument based on a Unihedron Sky Quality Meter-LR detector, which can be used by amateurs or can serve as a stand-alone instrument for night-sky brightness surveys.

Read the full paper here:

This paper explains a method of using the SQM-LR and a GPS to gather night-sky brightness readings over a large area.
SQM-LU-DL (Datalogging light meter) / Re: 3 new DLs installed...
« Last post by admin on March 20, 2015, 07:15:54 pm »
Thanks for the update Brian,

You may already be aware that the standardized header file format allows for a "Location name:" field that might help your define the various units. This information is stored in the "Configfile path:" which is viewable in UDM from "View-Directories". The udm.cfg file is a simple text file, and sections can be copied to that same file on your other computers so that they are all synchronized.

SQM-LU-DL (Datalogging light meter) / Re: 3 new DLs installed...
« Last post by darkwightskies on March 20, 2015, 06:51:32 pm »
Sorry to have taken so long to reply.

The fault was with us, a self inflicted wound!
We had a couple of laptops with old software on them and they threw the records into chaos. We share a "cloud" upload folder for each SQM location and nobody recorded which machine had uploaded data on each occasion.

As we have quite a few SQMs around the Island we need several data collectors but we had failed to update the Unihedron software on every machine.

I am sorry to have presented a problem of our own making to a public forum and can assure all readers of this that all SQM are working correctly and since we updated everything, all readings have been collected properly.

General Discussion / Reports from Spain
« Last post by admin on March 19, 2015, 11:29:10 pm »
You may be interested in these reports from Spain. Thanks to Jaime Zamorano for these:

Zamorano, Jaime y Muñoz Marín, Víctor Manuel (2010)
Calibration of SQM-L photometers for the NixNox project. [ LICA report; nº #01]

Zamorano, Jaime & Ruiz Carmona, Roque (2013)
Sky Quality Meter cross-calibration for the NixNox project. [ LICA report; nº #03]

Nievas Rosillo, Miguel & Zamorano, Jaime (2014)
*PySQM the UCM open source software to read, plot and store data from SQM photometers*

Zamorano, Jaime, Sánchez de Miguel, Alejandro, Martínez Delgado, David & Alfaro Navarro, Emilio (2011) Proyecto NixNox disfrutando de los cielos estrellados de España. Astronomía (142). pp. 36-42. ISSN 1699-7751

Zamorano, Jaime, Sánchez de Miguel, Alejandro, Nievas Rosillo, Miguel & Tapia Ayuga, Carlos (2014) NixNox procedure to build Night Sky Brightness maps from SQM photometers observations.

A night sky brightness network with data obtained with fixed SQM photometers of the Spanish Light Pollution Research Network.
Connected meters (SQM-LE/LU/LR/DL) / APT - Astro Photography Tool
« Last post by admin on March 19, 2015, 10:53:28 pm »
"Astro Photography Tool", a Swiss army knife for your astro imaging sessions now incorporates SQM readings. You can check out all the features at

Here is the latest screenshot demo:

General Discussion / Paper: Worldwide variations in artificial skyglow
« Last post by admin on February 13, 2015, 12:34:07 am »
Congratulations to Christopher C. M. Kyba, Kai Pong Tong, and many other contributors on the publication of their paper:

  Worldwide variations in artificial skyglow

From the Abstract:
Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope, and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by ~25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by ~5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.

Read the full paper here:

Much hard work was involved in gathering and standardizing readings from all over the world.
Weatherproofing / Unihedron enclosures
« Last post by BPO on January 08, 2015, 08:05:05 am »
Hi. One of my two enclosures recently lost its glass window for unknown reasons, possibly a combination of high UV exposure (it's on a mountaintop) and high winds.

So, don't forget to inspect your enclosures every now and again, just in case!

SQM-LU-DL (Datalogging light meter) / Re: 3 new DLs installed...
« Last post by admin on December 10, 2014, 10:33:13 pm »
Can you run a test locally to ensure that the units can record from battery and that you can retrieve the data? Such a test should only take an hour or two if your setting is on "once per hour".

Also, make sure that you are using the UDM software that came with the units or get the latest version from here:

I look forward to solving this issue.
SQM-LU-DL (Datalogging light meter) / Re: 3 new DLs installed...
« Last post by darkwightskies on December 10, 2014, 10:16:32 pm »
Thanks for the very quick response
  • All testing was done in the Data-logging mode
  • Threshold was initially set to 14 to avoid collecting daytime readings but as we are in a basically dark skies area it should have been overridden at night, it is now set to 0.
  • The LED was showing every minute
  • The  2 units have been reset to ensure compliance with the settings you suggest and will be checked again in a few days.
Once again, thanks for your reply, let's hope for some results when we next visit the sites… i'll let you know either way,
SQM-LU-DL (Datalogging light meter) / Re: 3 new DLs installed...
« Last post by admin on December 10, 2014, 04:02:12 pm »
There are two ways to gather readings with the DL meter:
  • Log continuous mode: Available from the information tab. This method does not set the internal battery operated datalogging features. If you initially tested the unit with this mode, then the battery operation settings will not be set to the same setting as in Log continuous.
  • Datalogging tab: Settings on the datalogging tab are stored in FLASH memory inside the meter. These settings control how the meter records while connected to the battery.

If you noticed that no readings are being recorded at all, then check the threshold setting on the datalogging tab. It should be 0. Anything greater will prevent datalogging on readings below that value.

Also, when plugging in the battery pack to the meter, the LED should be visible for three seconds every minute.

Please let me know if you have further questions or still have problems.
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