Calibration example Linz - Revision history

GuentherWuchterl: /* Calibration to theoretical twilight with linear and exponential part */

2014-07-30T16:25:00Z

‎Calibration to theoretical twilight with linear and exponential part

GuentherWuchterl at 16:23, 30 July 2014

2014-07-30T16:23:47Z

GuentherWuchterl at 16:22, 30 July 2014

2014-07-30T16:22:39Z

GuentherWuchterl at 16:21, 30 July 2014

2014-07-30T16:21:51Z

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T16:21:15Z

‎Improved calibration accounting for daytime sensor warming

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T16:16:30Z

‎Improved calibration accounting for daytime sensor warming

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T16:03:34Z

‎Improved calibration accounting for daytime sensor warming

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T16:02:25Z

‎Improved calibration accounting for daytime sensor warming

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T16:01:50Z

‎Improved calibration accounting for daytime sensor warming

GuentherWuchterl: /* Improved calibration accounting for daytime sensor warming */

2014-07-30T15:51:55Z

‎Improved calibration accounting for daytime sensor warming

@@ Line 154: / Line 154: @@
 == Calibration to theoretical twilight with linear and exponential part ==
-[[File:Linz_cal_07_linexpcal.png|thumb|Fig. 7: Fit of a linear + exponential relation between the counts that are output by the L3-Lightmeter and the calculated Sun and twilight. Included in the fit the determination of a constant background (typically light pollution).]]
+[[File:Linz_cal_07_linexpcal_res.png|thumb|Fig. 7: Fit of a linear + exponential relation between the counts that are output by the L3-Lightmeter and the calculated Sun and twilight. Included in the fit the determination of a constant background (typically light pollution).]]
 The basic properties of the sensor of the Lightmeter are a linear low-level part and an upper

@@ Line 97: / Line 97: @@
 == Check for time or longitude offset ==
-[[File:Linz_cal_04_time_offset.png|thumb|Fig. 4: Check for a time-offset. Note that the
+[[File:Linz_cal_04_time_offset_res.png|thumb|Fig. 4: Check for a time-offset. Note that the
 measured twilight lies asymmetric with respect to the calculated values. There is a time
 shift caused e.g. by a clock-error.]]

@@ Line 217: / Line 217: @@
 ===Comparison to a fit to the morning twilight===
-[[File:Linz_cal_07a_select_linexpcal.png |thumb|
+[[File:Linz_cal_07a_select_linexpcal_res.png |thumb|
 Fig. 7a: Calibration using the morning twilight and the Sun before noon.The calibration is somewhat different then the one obtained for the evening. It is rejected because inspection of the morning measurements show systematic effects that most likely come from the Sunlight passing over the city of Linz and its large industrial area. Note that after subtraction of the contribution of the city the twilight can be followed to the natural sky levels at 0.6 mlx!]]

← Older revision		Revision as of 16:21, 30 July 2014
Line 1:		Line 1:
	== Introduction: calibration approach for the Lightmeter Network ==		== Introduction: calibration approach for the Lightmeter Network ==
		+	Transferred to upgraded wiki --[[User:GuentherWuchterl\|GW]] ([[User talk:GuentherWuchterl\|talk]]) 18:21, 30 July 2014 (CEST)

	The Lightmeters, as any sensors, generate a signal as "counts" in an instrumental system. The counts are determined by the signal, the sensor-properties, the amplifier and the analog-digital converter. The "counts" need to be converted to numbers relating to a physical unit by means of a standard. Because the Lightmeter network is global and aims to monitor long-term changes of the night sky brightness, a globally accessible standard is needed that allows repeated checks over a long period of time. Therefore, one has to ensure		The Lightmeters, as any sensors, generate a signal as "counts" in an instrumental system. The counts are determined by the signal, the sensor-properties, the amplifier and the analog-digital converter. The "counts" need to be converted to numbers relating to a physical unit by means of a standard. Because the Lightmeter network is global and aims to monitor long-term changes of the night sky brightness, a globally accessible standard is needed that allows repeated checks over a long period of time. Therefore, one has to ensure

@@ Line 360: / Line 360: @@
     c_Watt = 2.57776395614e-09
-[[Bild:L3 cal 24Augallday residuals.png|thumb|Residuals for the fits above - 24th August]]
+[[File:L3 cal 24Augallday residuals_res.png|thumb|Residuals for the fits above - 24th August]]
-[[Bild:L3 cal 24Augallday residuals_detail.png|thumb|Residuals for the fits above (detail) - 24th August]]
+[[File:L3 cal 24Augallday residuals_detail_res2.png|thumb|Residuals for the fits above (detail) - 24th August]]
     Log:

@@ Line 337: / Line 337: @@
 <gallery>
 File:L3 cal 24Augallday2 Lux mit T 2009 DM log res.png|Calibration of the L3 Lightmeter in Linz, including a temperature-correction for sensor warming during daylight. Magenta line: Light-model, red: data used in calibration.
-File:L3 cal 24Augallday Lux mit T 2009 res.png| Logarithmic version of the image above to show the low light levels. Black line: calibrated measurements, green: minus background, red: data used in calibration
+File:L3 cal 24Augallday Lux mit T 2009 log_res.png| Logarithmic version of the image above to show the low light levels. Black line: calibrated measurements, green: minus background, red: data used in calibration
-File:L3 cal 24Augallday Lux mit T 2009 log detail.png|Detail of log-plot.
+File:L3 cal 24Augallday Lux mit T 2009 log detail_res.png|Detail of log-plot.
-File:L3 cal 24Augallday2 Lux mit T 2009 DM log.png|Calibrated data and total radiation model (cyan) used as calibrator to W/m²
+File:L3 cal 24Augallday2 Lux mit T 2009 DM log_res.png|Calibrated data and total radiation model (cyan) used as calibrator to W/m²
 </gallery>
-[[File:L3 cal 24Augallday Lux mit T 2009 mooncheck.png|thumb|Calibration of the L3 Lightmeter in Linz, including a temperature-correction for sensor warming during daylight. Check with Moon in Sept.]]
+[[File:L3 cal 24Augallday Lux mit T 2009 mooncheck_res.png|thumb|Calibration of the L3 Lightmeter in Linz, including a temperature-correction for sensor warming during daylight. Check with Moon in Sept.]]
      X = c ( b (a exp (n(1+dT)/a) - 1) + n )

@@ Line 336: / Line 336: @@
 <gallery>
-File:L3_cal_24Augallday_Lux_mit_T_2009.png|Calibration of the L3 Lightmeter in Linz, including a temperature-correction for sensor warming during daylight. Magenta line: Light-model, red: data used in calibration.
+File:L3_cal_24Augallday_Lux_mit_T_2009_res.png|Calibration of the L3 Lightmeter in Linz, including a temperature-correction for sensor warming during daylight. Magenta line: Light-model, red: data used in calibration.
 File:L3 cal 24Augallday Lux mit T 2009 log.png| Logarithmic version of the image above to show the low light levels. Black line: calibrated measurements, green: minus background, red: data used in calibration
 File:L3 cal 24Augallday Lux mit T 2009 log detail.png|Detail of log-plot.