AR2824 in Calcium K

Its been a long time since I've done any Calcium K solar imaging. The Calcium K wavelengths are into the near UV and represent excitation wavelengths of highly ionised calcium in the hot solar atmosphere.

 

Atmospheric seeing on Earth was poor to fair this morning but I thought I should see if my Calcium K set-up still works.

 

This is an image of Sunspot group AR2824 at the level of the Sun's chromosphere which is above the photosphere. The main features of the sunspot can be seen - umbra and penumbra but in addition, a paler network can be seen around the sunspot with a second concentration a little bit more distantly to the left.

 

These two zones represent the 2 poles of the magnetic field associated with the sunspot group. The lighter the pixel, the stronger the magnetic field. These light zones are called "Plages".

 

NASA can examine images like this with polarised light and determine which are N and S poles. See here for their equivalent of my image:

 

sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_HMIB.jpg

 

Intense white spots represent very strong areas of electromagnetic flux where solar flares or Coronal Mass Ejections may originate.

 

Celestron 1000mm f/10 Omni XLT refractor

Lunt B1200 CaK module

ZWO ASI 290 MM CMOS camera

Calcium K 1.25 inch filter (Double stacked)

Hinode solar finder/guider

Acquired with FireCapture v2.6

Stacked in Autostakkert!3

Wavelet sharpening in RegiStax6

 

FireCapture v2.6 Settings

------------------------------------

Camera=ZWO ASI290MM

Filter=Calcium K

Profile=Sun

Frames captured=5000

ROI=1936x1096

FPS (avg.)=166

Shutter=1.011ms

Gain=37 (6%)

Gamma=off

Histogram=91%

Limit=5000 Frames

Sensor temperature=28.6°C

Focuser position=0

Done