Log Book Entry No.173

Created: 16 Nov 2018 10:24:32

Last Revised: 23 Nov 2018 11:35:47

HughSpackman

PH3010 Solar Limb Darkening Setup

Logbook for PH3010 Solar limb darkening mini-project, initial setup meeting

Present: DB, MA, JC, HS

Order of tasks for observation of the sun:

1) DO NOT STARE DIRECTLY AT SUN. DO NOT POINT UNPROTECTED TELESCOPE AT SUN

2) Go outside dome and check that sun will not be obscured by the tree, wind thingy. If it will be, will have to wait before able to take images of sun

3) Check solar filters are not damaged. Fit solar filters to main scope (and if using finder scope, fit solar filter to that). Fit CCTV lens to camera, camera to filters, filters to telescope.

4) Open dome, move opening so that allows shadow of telescope to be seen on dome wall

5) Use the shadow of the top scope (the one secured by two sets of three prongs) to align the telescope with the sun. When the shadows from both sets of prongs overlap, the telescope is (roughly) aligned with the sun

6) If using finder scope, use to target edge of sun.

7) Use IC Capture program to view camera feed (really need to jam the cable into the back of the camera to get the pc to detect it). In device-properties can control gain and exposure settings

8) Use live camera feed to target edge of sun and focus (unlock and use know on back of telescope)

9) Change declination of telescope and monitor live camera feed. Need to find centre-line of sun. This is when any change in declination results in the suns edge moving out of frame (away from centre, only changing declination in one direction will move it out of frame - the other will move it more in frame)

10) On telescope control setup-targets-terrestrial or astronomical

terrestrial will keep telescope at fixed angle, astronomical follows objects through the sky

11) Choose filter to image with. Point telescope as closely as possible to centre of sun and view image histogram. Adjust and exposure until the image is not fully saturating (has a narrow yellow bar - the zero readings - visible) but has as full a range of values as practical.

12) Return telescope to point at edge of sun, in the centre. In IC capture go to the timed capture settings. Choose an appropriate target folder and image capture filenames, set the image type to bmp, turn the 'auto display capture' to off and set an appropriate capture interval and number of captures.

Note: Sun subtends an angle of about 0.5 degrees. Previous years have taken 405 seconds worth of images for this project.

13) capture images. Repeat step 11 onwards for another filter

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