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--- technical:description [2026/03/05 21:35] – [(3) First optical focus (F1) : light polarization analysis instrumentation] etienne
+++ technical:description [2026/03/17 15:57] (current) – etienne
@@ Line 12: / Line 12: @@
 Overall, the working characteristics of THEMIS are the following:
   * Observational electromagnetic spectrum range: 400-1100 nm
-  * Imaging field-of-view : ~2’x2’; square shaped
+  * Imaging field-of-view : ~2’x2’ square shaped without polarisation analysis; ~1’x1’ with polarisation
   * Overall focal ratio : f/62
   * Effective aperture: 92 cm
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 ==== (2) Full-Sun guider ====
-A full-sun guider has been setup on the telescope outer ring of the heat protection, near the 1m entrance plate. It uses a 45/500 mm objective, an Herschel prism, a neutral filter, a broadband (10 nm) green continuum 540nm photosphere filter (Baader Planetarium GmbH), and a ZWO ASI 178 mono (2000x3000 pixel²) CMOS camera. The full-sun guider image is always available in the control room of THEMIS. The full-Sun guider images are not meant for pure scientific analysis. Please note that given the location of the entrance pupil and depending on the telescope/dome relative positions, this guider may be momentarily obscured by the dome edge(for less than 30 seconds in any circumstance). <html><font color="#ff9900"> Camera settings can be changed by the user in the control room. Acquisition is left to the needs and appreciation of the user. </font></html>\\
+A full-sun guider has been setup on the telescope outer ring of the heat protection, near the 1m entrance plate. It uses a 45/500 mm objective, an Herschel prism, a neutral filter, a broadband (10 nm) green continuum 540nm photosphere filter (Baader Planetarium GmbH), and a ZWO ASI 178 mono (2000x3000 pixel²) CMOS camera. The full-sun guider image is always available in the control room of THEMIS. The full-Sun guider images are not meant for pure scientific analysis. Please note that given the location of the entrance pupil and depending on the telescope/dome relative positions, this guider may be momentarily obscured by the dome edge (for less than 30 seconds in any circumstance). <html><font color="#ff9900"> Camera settings can be changed by the user in the control room. Acquisition is left to the needs and appreciation of the user. </font></html>\\
  <html><font color="#0000ff"> The image from this camera is an available data product </font></html> [[observation:data#Full-sun  guider images| (cf. THEMIS data products)]].
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 ==== (8-9) Broadband Imaging (BBI) filter & camera ====
-If illuminated, the BBI camera offers a broadband high-resolution image with a square field-of-view of about ~55"x55". A broadband red filter, with a ~3nm passband centred around 656 nm is placed upstream of the camera. THEMIS BBI camera thus currently provides images or the red visible continuum.
+If illuminated, the BBI camera offers a broadband high-resolution image with a square field-of-view of about ~55"x55". A broadband red filter, with a ~3nm passband centred around 630 nm is placed upstream of the camera. THEMIS BBI camera thus currently provides images or the red visible continuum.
 THEMIS BBI camera is currently a 2000 x 2000 pixels Andor Zyla camera. This camera relies on the scientific CMOS technology (active-pixel sensor). This offers a high quality image of a subset of the THEMIS field-of-view with a very fast read-out, enabling the capture of a burst of images capture (up to 40 images/second) that are ideal for post image reconstruction. <html><font color="#ff9900"> Camera acquisition settings can be changed by the user in the THEMIS control room. Acquisition is left to the needs and appreciation of the user. </font></html>\\
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 If the slit-jaw slit configuration has been chosen at F2, the light not entering the spectrograph is captured by the slit-jaw camera. Slit-jaw images offers the context images of the spectrograph slit and allows a precise knowledge of the localisation of the slit.
-As almost all the remaining 15 watts of radiative power are then directed toward the camera, filters shall be place upstream of the camera to reduce the light flux. Presently a green continuum filter at XXX nm, with a 10 nm passband is used.
+As almost all the remaining 15 watts of radiative power are then directed toward the camera, filters shall be place upstream of the camera to reduce the light flux. Presently a green continuum filter at 540 nm, with a 10 nm passband is used.
 The slit-jaw camera is currently a ZWO ASI 178MM camera capturing the F2 field-of-view on a 3000x2000 pixels array. It's a CMOS camera. Without polarimetry, the field of view is 2'x2', while it is reduced to 2'x1' when polarimetric analysis are carried.