Telescopes

We have recently acquired a new professional level StellaLyra 16"-aperture telescope system to extend and enhance the University’s teaching and research in astrophysics. It is capable of performing high quality deep space astrophotography with high quality astro-imaging data output. The purchase of this instrument was made possible by the Cruickshank Trust.

The photo to the right shows the telescope set up in the atrium of the Zoology building for an outreach event in October 2024.

Telescope characteristics:

• 16" primary mirror diameter (40.6 cm)
• 3.25 m focal length (f / 8)
• Ritchey-Chrétien reflector design
• 800x magnification
• 95% reflectivity quartz mirrors
• 0.29" angular resolution, 200 times sharper than the human eye
• Virtually zero thermal expansion using strong carbon fibre frame
• Aberration-free optics, as used by HST, Keck, VLT, and other large professional telescopes

In the 2000s we acquired a Meade "Classic" LX200 10" Schmidt-Cassegrain telescope (25.4 cm primary mirror, 2.5 m focal length, f/10). This was installed in the Cromwell Tower Observatory (CTO) during its 2000s refurbishment, and at the time was a very popular commercially available instrument.

The image to the right shows Dr John Reid with the 10" telescope under the south dome of the CTO, circa 2000.

In 2023 the 10" telescope was removed from the CTO to prevent its further deterioration, and repaired and restored by BSc student Christopher Willett under the supervision of Dr Charles Wang.

Initial work was on the electronics, which had not worked for at least 10 years, with the optics to follow later. In principle the telescope could still be used manually if the electronics could not be repaired. The problem was identified as a short-circuited CPU capacitor that had resulted from an early manufacturer's modification to the "Classic" LX200 model to make it run on 18V rather than 12V. The image to the left shows the installation of the replacement component.

Restoration of the optics followed next. Most concerning was whether the actual optics had been destroyed by being left exposed to extreme weather cycles in the CTO for up to 20 years with no heating or air conditioning. The telescope tube was disassembled and a grainy deposit carefully cleaned off the Schmidt corrector plate (the lens at the entrance to the telescope tube). The images below show the lens before and after cleaning.

With these repairs done, the telescope was tested first in the Meston Building and later at Sheddocksley Sports Centre playing fields. The Aberdeen Astronomical Society kindly loaned two Akit 4000 CCD cameras, and Stellarium was installed for telescope tracking, Sharpcap for taking photos, and Astrosurface for image editing.

The tests identified a problem with focus or collimation, which was fixed thanks to some additional help from the AAS. One of the three collimating set screws had come out of its housing and was not moving the secondary mirror at all when adjusted. A final fix to the electronics was required when the DEC motor encoder blew (which had been repaired in the past but not replaced correctly).

The photo to the left shows the restored telescope being used to observe the Sun from the roof of the Fraser Noble Building in June 2025, by placement student Fraser Mackenzie from Robert Gordon’s College under the supervision of Dr Charles Wang.

In 2025 we acquired a 4.75"-diameter (120 mm) Sky-Watcher Evostar refracting telescope, primarily for outreach and solar observing. This is an achromatic telescope with a precision erecting prism diagonal and an equatorial mount.

Technical specifications:

• 4.75" / 120 mm objective lens
• 1 m focal length (f / 8.333)
• 40-100x magnification
• 9x50 optical finderscope
• Achromat lens to correct for chromatic aberration
• Potential for solar observing with a H-alpha chromosphere / prominence filter
• Sky-Watcher EQ3-2 GEQ (equatorial) mount
• StellaMira 2" 90^o Erecting Prism Diagonal to reverse up/down and left/right for easier viewing