Keep following that
DSS thread, I posted a bit more. Someone offered to analyze it in
DSS. Note my comments about the
LP and why Blue is stacked near-perfectly, while LPR is a mess. It may very well be caused by sideways incident light during LPR.
The flats for LPR and Blue are identical, normalized, to less than 1% error. Note also that the circular footprint is off to the right - I may have to adjust the axial position of my secondary (the dreaded #1 step of first-time collimation, should be a one-time action).
Bob if you want to play with Scilab, install the IPCV module after installing Scilab. I think it's done by using ATOMS, just search for it and you will find some pointers. Scilab itself is easy to install, and IPCV is not a big issue - just a 3rd party Scilab module.
You will end up writing code that looks something like this in a .sce file (I added some tile averaging functions, and cd to the directory above Flats, Light and Bias, // means commented out):
cd "C:\Users\aling\Pictures\astro\Objects\
NGC 2170";
function [x,y,z] = imLoad(fn, skip)
l = imread(fn);
[nx, ny] = size(l);
dx = int(skip/2);
dy = dx;
x = [dx+1:skip:nx-dx]';
y = [dy+1:skip:ny-dy]';
nx = length(x);
ny = length(y);
z = zeros(nx, ny);
for i = -dx:dx do
for j = -dy:dy do
z = z + double(l(x+i,y+j));
end
end
z = z/(2*dx+1)^2;
endfunction
function [x,y,z] = imLoad1(fn, skip)
l = imread(fn);
[nx, ny] = size(l);
x = [1:skip:nx]';
y = [1:skip:ny]';
l = l(x,
;
l = l(:, y);
z = double(l);
endfunction
skip=20;
fn = "Flat\Blue\MasterFlat_Gain210.tif";
[x,y,zfb] = imLoad(fn, skip);
fig1 = scf(1); clf(); plot3d(x,y,zfb);
fig1.children(1).data_bounds(1,3)=0;
//fig1.children(1).isoview="on";
title("Master flat Blue");
fn = "Flat\LPR\MasterFlat_Gain210.tif";
[x,y,zf] = imLoad(fn, skip);
fig8 = scf(8); clf(); plot3d(x,y,zf);
fig8.children(1).data_bounds(1,3)=0;
//fig8.children(1).isoview="on";
title("Master flat LPR");
fn = "Flat\Blue\MasterFlat_Gain210.tif";
zfi = ones(zf)./(zf/mean(zf));
//zfi = 1 + exp(2*(zfi-1));
fig7 = scf(7); clf(); plot3d(x/10000,y/10000,zfi);
//fig7.children(1).data_bounds(1,3)=0.9;
//fig7.children(1).isoview="on";
title("Master flat inverse normalized");
fn = "Bias\MasterOffset_Gain210.tif";
[x,y,zb] = imLoad(fn, skip);
fig2 = scf(2); clf(); plot3d(x,y,zb);
fig2.children(1).data_bounds(1,3)=0;
//fig2.children(1).isoview="on";
title("Master bias");
fn = "Light\Blue\NGC_2170_Light_001.tif";
[x,y,zl] = imLoad(fn, skip);
fig3 = scf(3); clf(); plot3d(x,y,zl);
fig3.children(1).data_bounds(1,3)=0;
fig3.children(1).data_bounds(2,3)=5000;
//fig3.children(1).isoview="on";
title("Single sub");
fn = "Light\Blue\AutosaveNGC_2170_Light_001.tif";
[x,y,za] = imLoad(fn, skip);
za = za - min(za);
za = za/max(za);
za = (2^16-1)*za;
za = min(2^16-1, 5*za);
fig6 = scf(6); clf(); plot3d(x,y,za);
fig6.children(1).data_bounds(1,3)=0;
fig6.children(1).data_bounds(2,3)=5000;
//fig6.children(1).isoview="on";
title("
DSS-stacked single sub");
z = (zl-zb).*(zfi-0.8);
//z = (zl-zb).*zfi;
z = min(z, 2^16-1);
fig4 = scf(4); clf(); plot3d(x,y,z);
fig4.children(1).data_bounds(1,3)=0;
fig4.children(1).data_bounds(2,3)=5000;
//fig4.children(1).isoview="on";
title("Corrected single sub");
//z = (zl-zb).*(zfi-0.6);
z = (zfb/mean(zfb)).*zfi;
fig9 = scf(9); clf(); plot3d(x/10000,y/10000,z);
//fig4.children(1).data_bounds(1,3)=0;
//fig4.children(1).data_bounds(2,3)=1.;
//fig4.children(1).isoview="on";
title("Comparison with LPR flat");
z = z - min(z);
z = z/max(z);
z = (2^16-1)*z;
z = min(2^16-1, 5*z);
z16 = uint16(z);
scf(5); clf(); imshow(z16);
fig5.children(1).isoview="on";
title("Corrected single sub");
return;
... Henk.
Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80,
Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall,
Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS,
DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles,
Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50,
Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK,
Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17",
Website:Henk's astro images
