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View from a Scope | October 20, 2017

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Totally Extreme Stargazing

Totally Extreme Stargazing

As far as stargazing goes it doesn’t get more extreme than looking at our own Sun. In this article i will go through the steps needed to safely look at the Sun through a telescope. I will also try and explain the different setups you can have and what you will be able to see with them.

FIRST A WORD OF WARNING: NEVER LOOK AT THE SUN THROUGH A TELESCOPE THAT DOESN’T HAVE THE CORRECT FILTERS. YOU WILL GO BLIND IF YOU DO.

I will probably mention the above warning a few times in this article but it is deadly serious, and as the title suggests makes this “Totally Extreme Stargazing”.

Filters

In an earlier article I described how to create your own solar filter

This type of filter is called a white light filter and for starters we will focus on this.

With a white light filter you will see Sunspots and potentially granulation on the surface of the Sun.

panamora_v3

As you can see in the photo above there some obvious sunspots as well as granulation on the surface, however with a white light filter the colour you see will be white. The photo above has had false colour applied to it.

The Setup

The great thing about observing the Sun is that for once you are not outside in the middle of the night in the freezing cold. Now you can enjoy the summer sun while still following the hobby you love.

  1. The first thing to do is setup your scope and mount as you would normally do, although you dont have to worry to much about polar alignment. A very rough alignment will do the job nicely.
  2. An important thing to keep in mind when solar observing is that the sun is an extremely powerful target and direct exposure could damage some of your telescope equipment. So while setting up be sure to keep the scope pointed away from the sun and keep the dust caps on both your main scope and finderscope.
  3. Once you are ready to start observing remove the dust cap and put your solar filter in place.
  4. You would think finding the sun in your telescope would be a fairly handy thing, after all it is big WP_000304bright and there is nothing else in the sky like it but i have found that it can be tricky enough to line it up right. What I do first is to look at the shadow of the telescope and try and make the shadow as small and square as possible. This way I can get a fairly good alignment without even looking through the eyepiece.
  5. Once you are happy with the shadow you need to center it in your eyepiece, this itself is still quite difficult. What works for me is to take the eyepiece out completly and look through the empty eyepiece holder directly at your primary mirror, you should be able to navigate the sun into the center of the mirror from there. Then just replace the eyepiece.
  6. At this point you should be able to directly view the Sun.

 

 

 

 

Visual observation using the white light filter will allow you to see

Sunspots in great details,

2x barlow sunspot

 

You may also so some filaments and limb darkening. This is when the edge of the sun seems to darken compared to rest of the disk.

600px-2012_Transit_of_Venus_from_SF

Imaging the Sun

I am still trying to nail down the best imaging technique using a white light filter on the Sun.

I have tried a combination of DSLR shots as well as webcam footage (stacked)

DSLR

sun_ps_highpass_stacked

The DSLR allowed me to image the entire disc of the Sun. The problem i came across was achieving focus. I used a Canon 400d which does not have live view. Achieving focus might be easier with live view.

You will need to play with the settings to get the best image. The above shot was taken using

Exposure: 1/250 sec

ISO: 100

You are probably best to play with the settings to get the best possible image.

Webcam Stacking

When using the webcam the image was magnified a great deal, This type of imaging would be good for capturing sunspots.

sun_spot_close_up

This is a stacked image using about 2000 frames.  Combining stacked images of the sun to form a full disk does not work anywhere as near as well as doing the same with the moon. However you can make out some good detail on the surface.

Please note that the colour in these shots was added via Photoshop. The view through a natural light filter is white.

The “creme de la mont”

In order to get great views of the Sun you will need a special filter called a Ha filter.

sep10_kw04

This filter comes in many forms however you need one that blocks all wavelengths except 656.281nm. To add these filters to a telescope can cost a lot of money. £2000 plus. Your best bet to get views and images like the one above would be to use a custom solar scope like a PST coronado. This will allow you to see the real detail of the Sun, Granulation will become immediately obvious and you ma even catch some flares.

These scopes come in at around £600. But bear in mind though for your £600 you get to do your favorite hobby, chilling in the sun and during a period of the year that night viewing is very limited.

Plus

It’s Extreme!!!!!

 

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