Orwell Astronomical Society (Ipswich)

Sketches Of The Sun, 04 June - 08 December 2023

Sketches of the solar disk made with the following instruments:

• OASI's Coronada Hα PST (Personal Solar Telescope) and various eyepieces. The instrument is an introductory model, intended more for visual rather than photographic use.
• A Celestron C4R 102 mm F9.8 refractor on a manually driven alt-az mount. To provide safe views of the solar disk in white light, the telescope was fitted with a Lunt 1.25" Herschel Wedge (diagonal) and an additional single polarizing filter fitted to the eyepiece (in accordance with instructions from Lunt). The eyepiece/filter combination could be rotated to adjust image brightness to a comfortable level.

Sketches made at the eyepiece of the PST were produced using a pencil and/or crayons. Some of the resulting images were scanned and subsequently post-processed in Gimp v2.6.

Sketches made at the eyepiece of the C4R were post-processed as follows:

1. Scan image to PDF using an HP Envy 5646 printer/scanner.
2. Copy/paste image into Microsoft Paint.
3. Flip image L-R horizontally to correct the effect of the diagonal.
4. Add black oval/circle to mask the edge of the solar disk.
5. Save image then copy/paste into GIMP 2.6 (1024 pixel square).
6. Bucket-fill the sky background black. Touch up remaining spots around the solar disk (paintbrush tool).
7. Save final image.

Sketched on 04 June 2023, 12:30-12:35 UT. Coronado PST with a Meade 26 mm Super Plossl eyepiece providing a magnification of 15.4x. The scanning process lost some detail but retained key features including prominances, plages, filaments and active regions. Clearly a lot was going on!

Sketched on 26 June 2023, 08:55-9:00 UT. OASI's Coronado PST with a Meade 26 mm Super Plossl eyepiece providing a magnification of 15.4x. The image features prominances, filaments and active regions.

Sketched on 17 August 2023, 15:00-15:20 UT. OASI's Coronado PST with a 20 mm Kellner eyepiece providing a magnification of 20x. The image features prominances, filaments and active regions. Left-right: orignal pencil sketch, scanned version with colour added, final version with marbling added to prove the most realistic representation of the view through the eyepiece.

Sketched on 06 December 2023, 11:45-11:50 UT. Celestron C4R with a Star 25 mm Plossl eyepiece providing a magnification of 40x.

Sketched on 06 December 2023, 11:45-11:50 UT using the Celestron C4R with a Star 25 mm Plossl eyepiece providing a magnification of 40x. Comparison with the preceding image shows the motion and evolution of active regions on the solar disk.

Neil Morley

Original: emails 18 June, 26 June, 19 December 2023.
Updated: 23 December 2023