A Half Hour in Hydrogen Alpha

The sun was shining this morning so, on my way to the bathroom for my morning cleanup and visit, I immediately turned on my new Ha (hydrogen alpha) solar filter so it could warm up.  This particular filter requires power to keep the etalon (interference filter) at the optimal temperature so I can see the most details.  The wavelength band varies very slightly by controlling the temperature of the etalon.  The more finely tuned the temperature setting, the more details you will see.  The filter requires about 10 minutes to warm up so I turned it on before washing up and brushing my teeth so it would be ready when I was ready for the day.

I then headed out into the frigid single digit temperatures (just like the other morning) with the battery pack in my pocket and the telescope and mount in my hands.  I carefully made my way down to the end of the icy driveway where I have an unobstructed view of the sun quite low in the southeastern sky.

I had far more success at pointing the telescope in the correct direction this time because I had mounted my homemade solar finder scope on the telescope.  The other morning, I used a manufactured solar finder and, honestly, it isn't all that great when compared to my homemade solar finder scope.  (See this blog entry to see an image of the homemade solar finder scope in action.)  My homemade solar finder scope has a large target printed on the back end of the scope in the form of a big bullseye.  I can see where the sun is located in reference to where my telescope is pointed even if it is only very roughly pointed in the direction of the sun.  That big bullseye makes it so much easier to just push the telescope into position so the bright dot (which is the sun) lands inside the very middle of the bullseye.  The manufactured solar finder only shows the tiny hole with an equally tiny translucent screen so you can't really tell how far out you are from the sun nor which direction you need to go.  It is actually a bit frustrating to use.  This morning, however, I used my own homemade solar finder scope and finding the sun was easy-peasy.  

I used my eyepiece that has the longest focal length this morning.  This 40mm Plossl eyepiece would show me the biggest chunk of the sky.  This allowed me to see the full disk of the sun in my field of view with a little bit of room to spare at the edges of my field of view.  My 32mm Plossl just barely allows me to see the full disk.  The 40mm shows a slight bit more of the field of view so it is more comfortable.  Actually, I'd like a little bit more room around the sun so I can watch prominences all around the sun at the same time and not have to worry so much about the sun drifting through my view.  That is a preference to address on another day though.  Today I was getting to know the filter a little better while also testing an aperture mask I had made the other day after my first morning testing this new filter.  (I will write more on the homemade aperture mask in another blog entry later.)

Today, the seeing conditions weren't great (not bad, but not great either) so there was less to see than I was able to see the other morning.  I was able to immediately see that the limb of the sun (the edge) was shimmering away, wavy and constantly moving, due to an unsteady atmosphere.  I think we had high winds aloft and that really affects the seeing conditions.  I could see that there was a very, very slight haze too and that is even worse for astronomy.  Because of these less than ideal seeing conditions, I knew that my views weren't going to show as much detail as compared to what can be seen on a better day.  

Still, I was able to distinctly pick out two sunspots, a filament, a third developing sunspot, a looping prominence, some other prominences, and what appeared to be longer, taller prominence extending far from the limb.  These are usually extending out from behind the limb and only visible against the blackness of space outside of the limb but I was able to see that it was rising from the surface of the sun on my side of the sun that is facing toward Earth.  That was interesting to see.

I was able to see the mottled, fiery surface of the sun too which was less visible the last time I observed a few mornings ago.  I attribute that to using the new aperture mask I made.  I'm still working on finding the best on-band tuning in the hope that I can see even more fine detail than I am currently seeing.  It is so cold outside, however, that I'm not sure the tuning knob is having much of an effect on the etalon.  This filter may work better in more moderate temperatures.  In a month or two when it is more comfortable to be outdoors for extended periods, the ambient outdoor temperature might be more suitable for this particular filter type.  Time will tell.  

When I came back indoors, I immediately pulled up today's imagery from the NSO (National Solar Observatory) so I could compare their imagery to my own observations.  They collect data and imagery from multiple locations around the globe.  I was pleasantly surprised to see that these images looked very much like what I had seen through the eyepiece this morning.  That was great news!  Here is an image from the NSO that fairly accurately portrays what I was seeing through the eyepiece this morning...

courtesy of the National Solar Observatory                

My view didn't show some of these features quite as prominently as we see in this photo but it was very close to this.  Also, my view did not have that bright yellow ring around the sun.  My view was all red.  The yellow ring is quite distracting and I don't think it should be here...  maybe they over-sharpened the image?  Regardless of the cause, this yellow outline ring around the sun was not in my view this morning.

Note:  It is days later and, after editing some of my own images (in this blog entry), I realized how the bright edge got into the NSO image above.  It was indeed due to processing the images after collecting all the data.  This is due to a mismatch in brightness levels between an exposure for the prominences (looks like flames shooting out from the edges of the sun but is really spraying hot plasma) and an exposure for the surface of the sun.  I have found that this distracting bright edge can be avoided if you are more careful with blending the two exposures.  Also worth mentioning is that although the Ha eyepiece does show a very red disk like we see in the NSO image above, these Ha images are more pleasing if you tone down the red.  

So, at the moment, I'm pretty happy with this new solar filter.  Once I get the hang of tuning my view to be more finely tuned on-band, I'll attempt to do some of my own imaging.  I don't want to be messing around with trying to image in the freezing cold anyway so I have some time.  Imaging requires far more equipment (more adapters, a better mount that tracks, a computer, even a second telescope for more close-up views) so it requires far more time too and time in single digit temperatures is not something I want to experience if I can help it.

I'm definitely looking forward to capturing some of my own images though!