Unihedron SQM-LU User manual

SQM-LU Operator’s Manual
c
Copyright 2005 - 2017
Version: 20170728
Company information
Mailing address Unihedron
4 Lawrence Avenue
Grimsby, Ontario L3M 2L9
Canada
Telephone [phone]
Fax [phone]
Website unihedron.com

Contents
List of Figures ........................................................ 5
List of Tables ......................................................... 6
1 Introduction ....................................................... 8
1.1 QuickStart ..................................................... 8
1.1.1 Othersoftware ............................................... 8
1.1.2 FITSintegration .............................................. 8
2 Measurements ...................................................... 10
2.1 Gettingaccuratereadings ............................................. 11
2.1.1 Seeingconditions.............................................. 11
2.1.2 Lightpollution ............................................... 11
2.1.3 Otherluminancescales .......................................... 12
3 Theory of operation ................................................... 14
3.1 Lightmeasurement................................................. 14
3.2 CommunicationtothePC............................................. 14
4 Specifications ....................................................... 15
5 Hardware connections .................................................. 16
6 Software development .................................................. 17
6.1 Writing your own software interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.2 Pascal ........................................................ 18
7 Unihedron Device Manager .............................................. 19
7.1 GettingUDM.................................................... 19
7.2 Installation ..................................................... 19
7.2.1 Systemrequirements............................................ 19
7.2.2 Windows .................................................. 19
7.2.3 Mac ..................................................... 19
7.2.4 Linux .................................................... 19
7.3 Operation...................................................... 20
7.3.1 Startup................................................... 20
7.3.2 Mainscreen................................................. 20
7.3.3 Mainmenu ................................................. 21
7.3.4 Filemenu.................................................. 21
7.3.5 Toolsmenu ................................................. 25
7.3.6 Helpmenu ................................................. 27
7.4 Informationtab................................................... 29
7.5 LogContinuous................................................... 29
7.6 Calibrationtab................................................... 33
7.7 ReportIntervaltab................................................. 34
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Contents
7.8 Firmwaretab .................................................... 34
7.9 Configurationtab.................................................. 35
7.9.1 Sensorarrangement ............................................ 36
7.10Simulationtab ................................................... 36
7.10.1 Simulationfromfile ............................................ 37
7.11Accessoryoptions.................................................. 38
7.11.1 Humidityaccessory............................................. 38
7.11.2 Displayaccessory.............................................. 38
7.11.3 LEDaccessory ............................................... 38
7.11.4 Relayaccessory............................................... 38
7.12Commandlineparameters............................................. 39
8 Commands and responses ............................................... 40
8.1 Commands ..................................................... 40
8.2 Responsedetails .................................................. 41
8.2.1 Readingrequest .............................................. 41
8.2.2 Unaveragedreadingrequest........................................ 41
8.2.3 Unitinformation .............................................. 42
8.3 Calibrationcommands............................................... 43
8.3.1 Calibration information request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.3.2 Lightcalibrationcommand ........................................ 43
8.3.3 Darkcalibrationcommand ........................................ 44
8.3.4 Disarmcalibrationcommand ....................................... 44
8.3.5 Manually set light calibration offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.3.6 Manually set light calibration temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.3.7 Manually set dark calibration time period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.3.8 Manually set dark calibration temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8.4 Accessoriescommands............................................... 47
8.4.1 Humidity / Temperture sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.4.2 Displayaccessory.............................................. 48
8.4.3 LEDaccessory ............................................... 49
8.4.4 Relayaccessory............................................... 50
8.5 Continuousreportingcommands ......................................... 51
8.6 Setting Interval reporting parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.6.1 Interval reporting period setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.6.2 Threshold setting for interval reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.6.3 Intervalsettingresponse.......................................... 54
8.7 Simulationcommands ............................................... 55
9 Installation ........................................................ 57
9.1 Mechanicalinstallation............................................... 57
9.1.1 Coverselection ............................................... 57
9.1.2 Covercalibration.............................................. 57
9.1.3 Covermaintenance............................................. 58
10 Default settings ..................................................... 59
11 Firmware upgrade .................................................... 60
11.1Details........................................................ 60
12 Calibration ........................................................ 61
12.1Recalibration .................................................... 61
12.2Lightcalibration .................................................. 61
12.3Darkcalibration .................................................. 61
12.4Confirmation .................................................... 61
4Unihedron SQM-LU Operator’s Manual - 20170728

13 Troubleshooting ..................................................... 62
14 Glossary .......................................................... 66
15 Bibliography ....................................................... 67
List of Figures
2.1 Mpsasinterpretivescale .............................................. 10
2.2 MpsasvsNELM .................................................. 13
4.1 Frontofunit .................................................... 15
4.2 Backofunit..................................................... 15
5.1 Wiredconnection.................................................. 16
7.1 Splashscreen .................................................... 20
7.2 Filemenu ...................................................... 21
7.3 FileOpendialog .................................................. 22
7.4 Viewmenu ..................................................... 22
7.5 View:Log ..................................................... 23
7.6 View:Directories .................................................. 23
7.7 Dataloggingheader ................................................ 24
7.8 SetLocationdialog................................................. 25
7.9 Tool:oldlogtodat ................................................ 26
7.10Tool:dattoMooncsv .............................................. 26
7.11Tool:Commterminal............................................... 27
7.12Helpmenu...................................................... 27
7.13Help:About .................................................... 27
7.14Founddevice(single)................................................ 28
7.15Founddevice(multiple) .............................................. 28
7.16USBconnectiondetails............................................... 28
7.17Ethernetconnectiondetails ............................................ 28
7.18RS232connectiondetails.............................................. 29
7.19Informationtab................................................... 29
7.20LogContinuouslyscreen.............................................. 30
7.21LogContinuouslyTriggertab........................................... 30
7.22LogContinuouslyThreshold............................................ 31
7.23LogContinuouslyAnnotationtab......................................... 31
7.24LogContinuouslyGPStab ............................................ 32
7.25Calibrationtab(initial) .............................................. 33
7.26Calibrationtab(populated)............................................ 33
7.27Reportintervaltab................................................. 34
7.28Firmwaretab .................................................... 34
7.29Firmwareselection ................................................. 35
7.30Configurationtab.................................................. 35
7.31Lightcalibrationconfirmation........................................... 36
7.32Darkcalibrationconfirmation........................................... 36
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7.33Sensorarrangement ................................................ 36
7.34Fig:Simulationtab ................................................. 36
7.35Accessoriestab ................................................... 38
9.1 Housing ....................................................... 57
9.2 Examplecovercalibration............................................. 58
List of Tables
2.1 Apparent Magnitudes of Known Celestial Objects adapted from [2] . . . . . . . . . . . . . . . . . . . . . . 10
7.2 simin.csvfielddescription ............................................. 37
7.3 Log continuous command line parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.4 Select device command line parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.5 Select device command line parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.1 Summaryofstandardcommands ......................................... 40
8.2 Readingrequestresponse ............................................. 41
8.3 Unaveraged reading request response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.4 Unitinformationrequestresponse ........................................ 42
8.5 Calibration information request response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.6 Lightcalibrationresponse ............................................. 43
8.7 Darkcalibrationresponse ............................................. 44
8.8 Disarmcalibrationresponse............................................ 44
8.9 Response for manual setting of light calibration offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
8.10 Response for manually setting of light calibration temperature . . . . . . . . . . . . . . . . . . . . . . . . 45
8.11 Response of manually setting dark calibration time period . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
8.12 Response for manually setting of dark calibration temperature . . . . . . . . . . . . . . . . . . . . . . . . 46
8.13 Humidity/temperature command summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.14 Humidity/temperature response summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.15 Display accessory command summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.16 Display accessory response summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.17LEDaccessorycommandsummary........................................ 49
8.18LEDaccessoryresponsesummary......................................... 49
8.19Relayaccessorycommandsummary ....................................... 50
8.20Relayaccessoryresponsesummary ........................................ 50
8.21Summaryofstandardcommands ......................................... 51
8.22 Continuous reporting command summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.23 Response of all continuous reporting requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.24Intervalreport ................................................... 53
8.25 Response of viewing or setting interval reporting parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.26 Response of request for internal simulation values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.27Requestsimulation(S....x)............................................. 55
8.28 Response of setting simulation values (S...x) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
13.1Readingseemtoobright.............................................. 62
13.2Readingis0.00mpsas................................................ 62
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13.3CannotFindUDMsoftware............................................ 62
13.4Drivernotfound .................................................. 62
13.5 USB device not found, or more than one device on the same COM port . . . . . . . . . . . . . . . . . . . 62
13.6Recordingstops................................................... 63
13.7MetercannotbefoundbyPC........................................... 63
13.8 Meter cannot be found by Windows operating system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
13.9Cannotgetareading................................................ 65
14.1Glossaryofterms.................................................. 66
List of Equations
2.1 MPSAS to cd/m2.................................................. 12
2.2 NELMtoMPSAS ................................................. 13
2.3 MPSAStoNELM ................................................. 13
8.1 RawTemperaturetodegC............................................. 55
8.2 degCtoRawTemperature............................................. 55
7

1 Introduction
Thank you for purchasing the SQM-LU. You will soon be on your way to collecting scientific data.
The SQM series of products have been used in the following applications:
•Quantitatively comparing the sky brightness at different astronomical observing sites.
•Documenting the evolution of light pollution.
•Setting planetarium dome illumination to mimic the skies that people are likely to experience elsewhere in the city.
•Monitoring sky brightness through the night, night-to-night, and year-to-year for astronomical observation records.
•Determining which nights show the greatest promise for finding the ’faintest fuzzies’.
•Calibrating the effect of sky brightness on qualitative measures such as the Bortle Scale or NELM.
•Investigating how sky brightness correlates with the solar cycle and month-to-month sunspot activity.
•Helping to provide local ground truth for future sky brightness prediction with the Clear Sky Clock.
•Helping CCD users make a correlation between the SQM reading and when the background reaches some ADC
level.
•Assisting Sea Turtle researchers in studying the amounts of light in areas where turtle hatchlings are affected by
artificial lights.
•Researching bird-song synchronization with dawn.
•Researching twilight brightness changes with the addition of external Neutral Density filters. Unihedron offers
adapters to attach such filters onto the meter.
1.1 QuickStart
1. Connect the SQM-LU meter to the computer with the supplied USB cable. Wait for any device drivers to automat-
ically load (if required). You may have to visit www.FTDIchip.com to get the latest VCP drivers if they do not get
installed automatically.
2. Ensure that your computer date and time is up-to-date.
3. Install and launch UDM (Unihedron Device Manager software supplied on the CD from your File Manager).
4. Click the “Find” button to find attached devices, then click on the SQM-LU that you connected.
5. Click on “Reading” to get a reading from the SQM-LU.
6. Logging and plotting can be done from the “Log Continuous” button.
1.1.1 Other software
•If you are using Windows, you may want to use Knightware SQM-Reader from www.knightware.biz/sqm .
•The CD contains examples of software (Perl, Python, etc.) for various functions that connect to the meter.
1.1.2 FITS integration
Some programs (listed below) gather information from the Unihedron Sky Quality meter products and insert that data
into the Flexible Image Transport System (FITS) header.
•MaxPilote (Freeware) incorporates SQM readings from an SQM-LE/SQM-LU into the FITS header while at the
same time provide constant readings in a live and updated Data Window.
8

1.1 QuickStart
•CCDAutoPilot
•FITS4Win2 uses the MPSAS keyword for sorting and filtering image files.
Unihedron SQM-LU Operator’s Manual - 20170728 9

2 Measurements
The SQM-LU provides readings in Magnitudes per square arcsecond, abbreviated as: mpsas, and written mathematically
as mag
arcsec2.
Mpsas is a logarithmic measurement which means that large changes in sky brightness correspond to relatively small
numerical changes. A difference of 5 magnitudes is a factor of 100 times the intensity. Therefore a sky brightness 5.0mag
arcsec2
darker corresponds to a reduction in photon arrival rate of a factor of 100.
The following schematic gives a rough idea of how to interpret the readings of the SQM:
Figure 2.1: Mpsas interpretive scale
Magnitudes are an astronomical unit of measure for object brightness. Brighter objects have a lower magnitude and
darker objects have a higher magnitude value. For example; a star that is 6th magnitude is brighter than a star that is
11th magnitude.
The star Vega is used a the reference point of ≈0 magnitude. Table 2.1 shows the apparent magnitude of some common
known celestial objects.
Table 2.1: Apparent Magnitudes of Known Celestial Objects adapted from [2]
App. Mag. Celestial Object
−26.73 Sun
−12.6 full Moon
−4.7 Maximum brightness of Venus
+0.03 Vega, the original zero point
+6 Faintest stars observable with naked eye
+27 Faintest objects observable in visible light with 8m ground-based tele-
scopes
+30 Faintest objects observable in visible light with Hubble Space Tele-
scope
Arcsecond is the definition of an arc being divided up into seconds as follows.
1. There are 360 degrees in a circle.
2. There are 60 arcminutes in a degree, and 21600 arcminutes in a circle.
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