Images of the Sun in Hydrogen Alpha

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Solar Photosphere and Chromosphere

Light radiates from the photosphere of the Sun's shell, the 100km thick inner layer of the solar surface. Images of the photosphere reveal features such as sun spots, spicules, filaments, prominences (edge and surface), ribbons, and grannules. To learn more about the solar photosphere, click here.

The chromosphere is the second of three main layers of the Sun's atmosphere and is roughly 2,000 kilometers deep. It sits just above the photosphere where coronal ejections, prominences and solar flares can be observed. A coronal mass ejection (CME) is an unusually large release of plasma and magnetic fields from the chromosphere. CMEs follow solar flares and and are normally present during a prominence eruption. For more Information on the solar chromosphere, click here.

 

About the Images

Equipment: The images below (and those in the archives) were captured using Lunt 80mm or Lunt 100mm dedicated Ha solar telescopes with hydrogen-alpha filters centered on a wavelength of 6562.81 Angstrom having a <0.7A bandwidth. More recent images were captured using a DSII double-stack etalon module, narrowing the bandwidth from 0.7A to 0.5A to increase detail of the surface (photospheric) features. Harmful emissions are further blocked by an 18mm blocking filter. A high resolution video camera is used to record dynamic changes in the sun's photosphere and chromosphere. My current camera is a Point Grey Grasshopper with a USB3 interface instrumented with a 0.83" CMOS chip. A Televue Powermate 2.5x barlow is often used to increase resolution.

Solar H-alpha telescopes are equipped with etalons for tuning the Ha bandwidth (e.g. by pressure tuning or tilting) to compensate for the high velocities (Doppler effect) that characterize fast moving prominences and ejections.

Data Acquisition: Video images are acquired using frame rates ranging from 42/sec (full frame) to over 150 f/s (for selected regions of interest). Generally, I'll collect 1000 frames per file. A 42 f/s 1000 frame exposure takes 23.8 seconds. A typical imaging sessions involve collecting 10-15 video files from different regions of the sun, retuning to bring out prominenences, or refocusing to compensate for changing sky conditions. Each file is approx 4.5GB in size. Needless to say, file management and image back-up can be a challenge. Currently using FireCapture v2.4 for data acquisition.

Workflow: Video files are automatically analyzed to select the sharpest 15-25% of frames. These frames are then registered using several alignment points and stacked to create a single 16-bit image file. A single image comprised of a stack of 15% is effectively a 3.57 second cumulative exposure (15% of a 23.8 second video file is 3.57 seconds). Stacking is done using AutoStakkert 2.0. The image then undergoes wavelet sharpening (RegiStax 6.0) and further processing such as inverting, colorizing, sharpening, and noise reduction (Photoshop CS 6).

 

Sun in Ha on 9/10/17

9/10/17

 

Sun in Ha on 9/10/17

9/10/17

 

Sun in Ha on 9/7/17

9/7/17

 

Sun in Ha on 9/2/17

9/2/17

 

Sun in Ha on 9/2/17

9/2/17

 

Sun in Ha on 8/30/17

8/30/17

 

Sun in Ha on 8/29/17

8/29/17

 

Sun in Ha on 8/29/17

8/29/17

 

Partial Eclipse 8/21/17

 

8/21/17

 

8/16/17

8/16/17

 

803/17

8/3/17

 

7/8/16

7/8/17

 

7/8/17

7/8/17

 

6/16/16

6/16/17

 

5/23/17

5/23/17

 

5/23/17

5/23/17

 

5/22/17

5/22/17

 

5/8/17

5/8/17

 

4/28/17

4/28/17

 

4/20/17

4/20/17

 

4/20/17

4/20/17

 

4/20/17

4/20/17

 

April 5, 2017

4/5/17

 

April 1, 2017

4/1/17

 

April 1, 2017

4/1/17

 

April 1, 2017

4/1/17

 

March 24, 2017

3/24/17

 

February 23, 2017

2/23/17

 

February 15, 2017

2/15/17

 

February 12, 2017

2/12/17

 

Lunt 100 mm Solar Scope

Lunt LS100THa/PT DSII

In service from 4/16 - present

714 mm focal length; f/7 dedicated H-alpha telescope.

0.5A bandwidth centered on Ha at 6562.81A

PointGrey Grasshopper USB3 CMOS camera

2 inch Feathertouch Focuser and 18mm blocking filter.

 

Lunt 80mm Solar Scope

Lunt LS80THa/PT DSII

Used from 12/14 - 2/16

560mm focal length; f/7 dedicated H-alpha telescope.

Double stack (DSII) etalon = 0.5A bandwidth

PointGrey Grasshopper USB3 CMOS camera

2 inch Crayford Focuser and 18mm blocking filter.

 


Image Archives

2014-2015

2016

 

A few links to Solar Images from NASA and on-line Media:

Click here to visit very useful information on sunspots and active regions

Click here for a drawing of the outer layers of the Sun (credit: sciencenordic.com)

Click Here for the closest images ever taken of the Sun

Click here for a NASA image from the SDO taken on Sept. 30, 2014 in extreme UV light. The Earth is shown to scale.

Click Here for current (up to the minute) Ha images of the sun from 7 NSO solar observatories