Recent changes to Home

Home modified by Peter Fontein

Peter Fontein — Wed, 08 Jul 2020 15:58:07 -0000

--- v17
+++ v18
@@ -20,13 +20,5 @@
 0.11 beta: added tracking error, moon phase and improved help
 0.1 beta: first commit

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-To add a new page simply reference it within brackets, e.g.: [SamplePage].
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-The wiki uses [Markdown](/p/astropicturesimulator/wiki/markdown_syntax/) syntax.
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 [[members limit=20]]
 [[download_button]]

Home modified by Peter Fontein

Peter Fontein — Wed, 08 Jul 2020 15:57:19 -0000

--- v16
+++ v17
@@ -1,7 +1,11 @@
 **Restriction:**
-Note that SNR calculations become complex in case the signal is truncated in any way, either by reaching the limits of the AD converter or in case the sensor reaches its full well limits. No conclusions should be drawn from SNR values in the red and yellow zones of the "Optimize SNR" tab. SNR values inside these regions are constructed such that they will be lower than those in the non-truncated region.  As a result the optimum will always be found in the non-truncated region. In certain cases it may appear that this is not the case, but that is a consequence of the discrete choices available (the optimal value may be in between two available choices).
+Note that SNR calculations become complex in case the signal is truncated or clipped in any way, either by reaching the limits of the AD converter or in case the sensor reaches its full well limits. No conclusions should be drawn from SNR values in (or very close to) the red and yellow zones of the "Optimize SNR" tab. SNR values inside these regions are constructed such that they will be lower than those in the non-truncated region.  As a result the optimum will always be found in the non-truncated region. In certain cases it may appear that this is not the case, but that is a consequence of the discrete choices available (the optimal value may be in between two available choices).

-In practical situations you might prefer clipping of (at least part of) the signal, e.g. bright stars. Do not go blind on the values presented. The most useful takeaway for me is that settings like gain and exposure time are less critical than you might think. 
+After some interesting experimentation with simulated truncated distributions I decided that incorporating this in the program does not add any value. In many cases the differences are negligible. Where differences are found this has to do with the precise definition of SNR in a clipped situation and not so much with getting an optimal exposure (where you do not want clipping of the target of interest). Note that in practical situations, you should probably allow for clipping of  bright stars in case these are not your actual target of interest.
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+So do not go blind on all the values presented. The most useful takeaway for me is that settings like gain and exposure time are less critical than you might think in case you stack images. 
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+No updates past 2.06 are foreseen in the near future.

 **Version history:**
 2.06 mostly internal changes to simplify testing. Visible changes: help states restriction with respect to SNR values in case of clipping. Values at full well may differ slightly from version 2.01.  Calculated optima are equal to 2.01. No need to switch to 2.06 if you have 2.01.

Home modified by Peter Fontein

Peter Fontein — Tue, 30 Jun 2020 19:14:57 -0000

--- v15
+++ v16
@@ -1,7 +1,10 @@
 **Restriction:**
-Note that SNR calculations become complex in case the signal is truncated in any way, either by reaching the limits of the AD converter or in case the sensor reaches its full well limits. No conclusions should be drawn from SNR values in the red and yellow zones of the "Optimize SNR " tab. SNR values inside these regions are constructed such that they will be lower than those in the non-truncated region.  As a result the optimum will always be found in the non-truncated region. In certain cases it may appear that this is not the case, but that is a consequence of the discrete choices available (the optimal value may be in between two available choices).
+Note that SNR calculations become complex in case the signal is truncated in any way, either by reaching the limits of the AD converter or in case the sensor reaches its full well limits. No conclusions should be drawn from SNR values in the red and yellow zones of the "Optimize SNR" tab. SNR values inside these regions are constructed such that they will be lower than those in the non-truncated region.  As a result the optimum will always be found in the non-truncated region. In certain cases it may appear that this is not the case, but that is a consequence of the discrete choices available (the optimal value may be in between two available choices).
+
+In practical situations you might prefer clipping of (at least part of) the signal, e.g. bright stars. Do not go blind on the values presented. The most useful takeaway for me is that settings like gain and exposure time are less critical than you might think.

 **Version history:**
+2.06 mostly internal changes to simplify testing. Visible changes: help states restriction with respect to SNR values in case of clipping. Values at full well may differ slightly from version 2.01.  Calculated optima are equal to 2.01. No need to switch to 2.06 if you have 2.01.
 2.01 bug fixed
 2.0 calculates optimal gain, note: contains bugs, to be tested
 1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc.  Added extra info in groupboxes.

Home modified by Peter Fontein

Peter Fontein — Tue, 30 Jun 2020 18:47:37 -0000

--- v14
+++ v15
@@ -1,4 +1,7 @@
-Version history:
+**Restriction:**
+Note that SNR calculations become complex in case the signal is truncated in any way, either by reaching the limits of the AD converter or in case the sensor reaches its full well limits. No conclusions should be drawn from SNR values in the red and yellow zones of the "Optimize SNR " tab. SNR values inside these regions are constructed such that they will be lower than those in the non-truncated region.  As a result the optimum will always be found in the non-truncated region. In certain cases it may appear that this is not the case, but that is a consequence of the discrete choices available (the optimal value may be in between two available choices).
+
+**Version history:**
 2.01 bug fixed
 2.0 calculates optimal gain, note: contains bugs, to be tested
 1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc.  Added extra info in groupboxes.

Home modified by Peter Fontein

Peter Fontein — Sun, 28 Jun 2020 08:57:06 -0000

--- v13
+++ v14
@@ -1,4 +1,5 @@
 Version history:
+2.01 bug fixed
 2.0 calculates optimal gain, note: contains bugs, to be tested
 1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc.  Added extra info in groupboxes.
 1.25 restructured a lot (compared to 1.21) to simplify testing and added unit tests to get more confidence in results

Home modified by Peter Fontein

Peter Fontein — Sat, 27 Jun 2020 21:24:20 -0000

--- v12
+++ v13
@@ -1,4 +1,5 @@
 Version history:
+2.0 calculates optimal gain, note: contains bugs, to be tested
 1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc.  Added extra info in groupboxes.
 1.25 restructured a lot (compared to 1.21) to simplify testing and added unit tests to get more confidence in results
 1.21 fixed error in SNR at values of gain other than 1.0. Added SkyMag (in addition to Bortle), fixed label of offset (ADU instead of electrons)

Home modified by Peter Fontein

Peter Fontein — Fri, 26 Jun 2020 19:19:00 -0000

--- v11
+++ v12
@@ -1,5 +1,5 @@
 Version history:
-1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc. Added extra info in groupboxes,
+1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc.  Added extra info in groupboxes.
 1.25 restructured a lot (compared to 1.21) to simplify testing and added unit tests to get more confidence in results
 1.21 fixed error in SNR at values of gain other than 1.0. Added SkyMag (in addition to Bortle), fixed label of offset (ADU instead of electrons)
 1.2 SNR calculation simplified and now conform standard (noise of signal included in denominator)

Home modified by Peter Fontein

Peter Fontein — Fri, 26 Jun 2020 19:14:57 -0000

--- v10
+++ v11
@@ -1,4 +1,5 @@
 Version history:
+1.5 added a tab to calculate optimal exposure time due to frames ruined by passing satellites, airplanes etc. Added extra info in groupboxes,
 1.25 restructured a lot (compared to 1.21) to simplify testing and added unit tests to get more confidence in results
 1.21 fixed error in SNR at values of gain other than 1.0. Added SkyMag (in addition to Bortle), fixed label of offset (ADU instead of electrons)
 1.2 SNR calculation simplified and now conform standard (noise of signal included in denominator)

Home modified by Peter Fontein

Peter Fontein — Thu, 25 Jun 2020 15:20:25 -0000

--- v9
+++ v10
@@ -1,6 +1,5 @@
 Version history:
-this is still work in progress, it runs, but the numbers might change
-most recent code has same functionality as 1.21 but is restructured to facilitate unit tests
+1.25 restructured a lot (compared to 1.21) to simplify testing and added unit tests to get more confidence in results
 1.21 fixed error in SNR at values of gain other than 1.0. Added SkyMag (in addition to Bortle), fixed label of offset (ADU instead of electrons)
 1.2 SNR calculation simplified and now conform standard (noise of signal included in denominator)
 1.1 added nebulosity, added total time in groupbox, fixed bug for small SNR

Home modified by Peter Fontein

Peter Fontein — Wed, 24 Jun 2020 19:59:12 -0000

--- v8
+++ v9
@@ -1,5 +1,6 @@
 Version history:
 this is still work in progress, it runs, but the numbers might change
+most recent code has same functionality as 1.21 but is restructured to facilitate unit tests
 1.21 fixed error in SNR at values of gain other than 1.0. Added SkyMag (in addition to Bortle), fixed label of offset (ADU instead of electrons)
 1.2 SNR calculation simplified and now conform standard (noise of signal included in denominator)
 1.1 added nebulosity, added total time in groupbox, fixed bug for small SNR