PCW Memorial Observatory – Erika Rix

As we transition out of the solar minimum and into the solar maximum, it’s a great time to try your hand at sketching the full solar disk. As if sketching prominences weren’t tricky enough, or even just sketching sunspots using a white light filter, sketching the entire Sun in hydrogen alpha means rendering additional features such as filaments, plage, active regions, and possible flare activity.  Creating the mottled appearance of the “surface”  itself can be very challenging. If you take it one step at a time, it won’t be as overwhelming as first believed.  Hopefully this tutorial will help you along the way.

H-alpha Full Solar Disk

Observing Tips:

• Remember that solar observing is affected by the same conditions that night-time observing is: the Sun beating down on pavement or wood decks creating quivering views, winds, eyepieces fogging up from your breath in the colder months/sweat from your eyebrows in the hotter months, even dark adaption (yes…having your eyes adjust to the darker views of hydrogen alpha so that you can see the faintest of details in prominence structure). Pick your location wisely to give you the best views for that day’s weather conditions.

• Your eyes can detect movement sometimes easier than they can the fainter details. Some filters don’t have a flat bandwidth nor a flat field of view. Different solar features have slightly different optimal bandwidths. So…have a play with those knobs to get the most out of your session. Scan back and forth slowly, move the FOV around, notice the features popping in and out of bandwidth.

• Outside light around the eyepiece cups will prevent you from seeing the fainter details. Eye cups, towels, proper solar cloths, or even a cardboard solar shield, will help.

Sketching Tips:

• Use grid lines or triangles to assist you for proper placements of features. Also, the larger your circle, the easier it is to fit in all the details…which in turn will keep the “super-size” temptation at bay.

• The types of paper and pencils you use can hinder or help you. Things to consider: sunlight glare on your paper will temporarily give you blind spots when you try to observe again after adding a marking (worse with white paper – think dark adaption when you put your eyes back to the eyepieces), texture, smudges or holds the pencil markings, colors…

 
 
 
Sketching Tutorial:

• Draw a large circle with your compass. Fill it in with the flat of your Conte’ crayon.

• Blend with clean, dry fingertips. I’ve tried chamois, brushes, blending stumps, and a variety of other blending tools for this step. Each one removed too much of the Conte’. The combination of the Strathmore Artagain paper’s tooth and a light blending of my fingertips produced the most accurate representation of mottling.

• If you go outside the lines, use a flattened eraser tip to cleanly remove the stray markings.  I use a utility knife to flatten the eraser tip to resemble a flat-head screwdriver.

• Draw the prominences around the limb. Use a sharpened Conte’ pencil for the brightest areas and the white watercolor pencil for the fainter ones.

• Add sunspots with a black wax pencil or charcoal. I use the sunspots and prominences as anchors to assist with proper placements of all the other features.

• Plage is added with the Conte’ pencil. Really study the active regions and be specific with your markings, placing each stroke as accurately as you can. Again, don’t be afraid to adjust the tuning of your scope to tease out details.

• Add dark contrast and filaments with a combination of charcoal and the black wax pencil. The charcoal will be more subtle and the wax/oil will be more dramatic.

• Continue working, making your way in sections across the entire disk. Scan thoroughly once again, making minor adjustments to the tuning to ensure you don’t miss out details.

• To finish it off, I scan my sketch or take a photograph of it, adjust the brightness/contrast to match the true appearance of my sketch, and then I insert a graphic from the Tilting Sun program that shows the orientation for my scope and mount (dependent on how my diagonal is turned and where I am sat behind the eyepiece) and any useful information concerning my observation.

~ by Erika Rix on November 27, 2010.

Posted in Solar Sketching
Tags: active regions, artagain, charcoal, conte', filaments, full disk, H-alpha, Maxscope 60mm, prominences, solar disk, solar sketches, Strathmore Artagain, Sun