Barton Lake Instruments · Software

Sky Quality Meter Workbench

Record, chart and publish your sky's darkness, every night, from a Unihedron Sky Quality Meter.

Download 1.0.0 Free · Windows 10 and 11 · SQM-LE and SQM-LU
Chart of the night of 13 March 2025 at Barton Lake Observatory: sky brightness falls to about 17 mpsas under a full moon, then rises above 20 mpsas between 2 and 4 a.m. during a total lunar eclipse.
13 March 2025: a full moon all night, then a total lunar eclipse darkening the sky by two magnitudes between 2 and 4 a.m.

Your sky, night after night

Sky Quality Meter Workbench connects to your SQM-LE or SQM-LU, records the sky's brightness through the night on a schedule worked out from sunset and twilight at your site, and keeps every reading on your computer.

Look back over a single night or years of them, see how the moon shaped each one, and keep a live chart of tonight's sky on your website.

What Workbench does

Scheduling

Records on its own

Set your site once. Workbench works out sunset and twilight for every night, starts and stops by itself as the seasons change, and can start with Windows so an observatory computer recovers from a restart.

Storage

Every reading kept

Readings are stored on your computer with exactly what the meter sent back. Bring in your existing sqm_reading_<date>.txt files, and keep writing them for other software that reads them, such as ASCOM drivers.

History

Your history at a glance

SQM History shows your nights as a table, a trend or a calendar, by night, week, month, season or year, coloured by Bortle class. Open any night to see every reading.

Moon

The moon, accounted for

The calendar shows the moon's phase on every date, charts can draw the moon's path across the night, and one tick box leaves out readings taken while the moon was up.

Publishing

Publish tonight's sky

Keep tonight's chart and a small reading card up to date through the night, and upload them to your website by FTP, FTPS, SFTP or Amazon S3.

Charts

Seven chart styles

From a high-contrast chart for a website to black and white for print, in light or dark mode.

A look inside

SQM History calendar view for January and February 2026, each night shaded by Bortle class with its mean reading and a moon-phase icon.
Every night at a glance, coloured by Bortle class, with the moon's phase.
SQM History trend view plotting a month of nightly readings against Bortle class bands.
A month of nights against the Bortle classes.
Night detail window showing one night's chart and the list of individual readings.
Any night in detail, down to a single reading.
The eclipse night drawn in the Publication chart style. The eclipse night drawn in the Slate chart style. The eclipse night drawn in the Parchment chart style.
Seven chart styles. Here are three of them, all showing the same eclipse night.
Options dialog, Schedule page, set to record from sunset to sunrise.
Records sunset to sunrise, recomputed every night.

Download

Free · Version 1.0.0 · 26 October 2026

Sky Quality Meter Workbench 1.0.0

59.7 MB · Windows 10 and 11, 64-bit. The installer includes everything Workbench needs; installing it needs administrator rights.

Download the installer What's new in 1.0.0 Read the user guide

Windows may show “Windows protected your PC” the first time you run the installer. Click More info, then Run anyway.

SHA-256 ED64DE3159AD49EFBC6EB86447E64375B56C008D46CD30B9564D7DF72023652C

Good to know
  • Works with the SQM-LE and SQM-LU, on 64-bit Windows 10 and 11.
  • Never changes your meter's calibration or settings.
  • Your readings stay on your computer unless you choose to publish them.
  • Free to download and use, with free updates: Help ▸ Check for Updates tells you when a new version is out.

Questions, bug reports and feature suggestions are all welcome by email: support@bartonlakeinstruments.com