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Connected meters (SQM-LE/LU/LR/DL) / Re: FTDI driver installation problems
« Last post by admin on September 10, 2015, 07:55:45 pm »
Clearing Windows COM list

After installing different FTDI devices in Windows, the system fills up with COM port numbers.

You should prevent auto update as identified in the previous post, then ...

If you are very careful, it is possible to clear off all the "used" COM ports by following the instructions at this link:

Connected meters (SQM-LE/LU/LR/DL) / Re: FTDI driver installation problems
« Last post by admin on September 10, 2015, 07:41:57 pm »
Installing Windows FTDI driver manually (preventing auto-update)

Just recently, Microsoft seems to have stopped providing FTDI drivers automatically for Windows 7 (and possibly other versions).

This can be a problem because connecting an FTDI device to the USB port usually initiates an automatic check for updated drivers and failure to find such a driver at Microsoft results in a failed driver installation.

You can turn off automatic updates to prevent this as follows:
  • Open the: Control Panel -> System Security -> Windows Update
  • Select Change settings
  • Deselect Recommended updates
  • Press OK

You can now manually install the FTDI driver from

Then plug in the SQM-LU device.
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.
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