Primary and Secondary Mirrors Resilvered

I am pleased to report that the Alan Young Telescope at Cranbrook School, is now again in working condition.

Both mirrors of this large reflecting telescope, primary and secondary mirrors, have been re-silvered by Orion Optics.

Here is a photo by Graham Caller,

Mirrors Re-Installed In The Alan Young Telescope

Mirrors Re-Installed In The Alan Young Telescope

Photo taken just after the mirrors were reinstalled after their recoat by Orion Optics.

Resilvering The BIG Mirror

This morning, Rod and Ted of the CADSAS committee dismantled parts of the Alan Young telescope to remove the big 22.5″ primary mirror and the smaller secondary mirror.

The mirrors will be sent to Orion Optics very soon.

Orion will re-coat both mirrors.  We are hopeful their service will greatly improve the mirrors’ reflectance of light and therefore our imaging results.

Although often still referred to as “silvering”, the Orion recoating does not use silver. The modern and widely accepted Hilux coating, uses aluminium in the mirror coating process.

Come and visit in the Autumn when it’s dark again and see the results.

Lunar Images From Our Recent Autumn Skywatch Public Meeting

We held an Autumn Skywatch on 10th October for our members and the general public who wanted to come along. The clouds did not look promising that afternoon, but cleared pretty well by 8pm.

Many of our telescopes were set up outside and a good range of astronomical targets were observed, guided by our more knowledgeable members.

Here are three images captured that night with our big telescope, the Alan Young. They have been reduced in resolution for the web.

Clvius and Tycho

Clavius and Tycho

Archimedes and Plato

Archimedes and Plato

Monte Apenninus and Caucasus

Monte Apenninus and Caucasus

Albireo imaged with Alan Young Telescope

Star Albireo imaged with Alan Young Telescope 06062014

Albireo imaged with Alan Young Telescope 06062014 (click for larger version)

An image of double star Albireo in constellation Cygnus, imaged with the Alan Young Telescope.

Albireo consists of an orange giant of magnitude 3, together with the blue/green magnitude 5 companion.

It is good to see that our work on improving the Alan Young Telescope is now producing results, in the form of better quality astro-images.

Orion Nebula Image – Fluorescent Light White Balance

Orion Nebula M42 image captured using Fluorescent Light White Balance

Last night Ted suggested taking images in fluorescent light setting (rather than the normal White Balance), based on advice on his Northern Lights trip.

So we did.  Here is a resulting image of the Orion Nebula.  The colour temperature of Fluorescent light is lower (warmer – more yellow)

Additional data:-

The Canon dSLR has eight white balance presets on its cameras.

AWB (Auto White Balance) will look at any scene as it’s being shot and attempt to neutralize the color it sees from 3000-7000 K.

Daylight uses Canon’s default color temperature of 5200 K;

Shade works at 7000 K; Cloudy at 6000 K; Tungsten at 3200 K; White Fluorescent is set to 4000 K (there are huge color temperature variations in fluorescent lights); Flash at 6000 K; and Custom White Balance, which can neutralize light with a color temperature anywhere between 2000 and 10,000 K.

Jupiter images, including a composite with moons

On Monday (5th November – with fireworks exploding nearby) we captured some images of Jupiter with the Alan Young telescope.

We used raw format on the Canon dSLR (.CR2), for the images.

(Captures by Ted Pearson, composite image by Kevin Brown using

Here is an image of Jupiter:

jupiter captured 051112 in canon dslr raw format


And below, a composite image of Jupiter (1/200 second exposure) and its four “Galilean” moons – Io, Europa, Ganymede and Callisto (1/4 second exposure).

Jupiter and  four of its moons - composite image


Stepper Motor Drive For Declination Axis – Successful Test Flight!

Declination Axis Stepper Motor Drive Test

Declination Axis Stepper Motor Drive Test

Today we tested the newly developed mechanism for the Alan Young telescope’s declination axis drive. It is powered by a stepper motor, controlled by an Arduino microprocessor and EasyDriver board.

We have fabricated a system of three belts and pulleys to give a reduction ratio of 398:1.  This means the stepper motor running at a practical maximum speed of 30 rpm, produces a slew rate of around 0.5 degrees per second.

The motor is controlled by software running on the Arduino and so its rotation speed can be easily slowed to give a lower slew rate, as we did today.

When testing it today for the first time, it worked well and easily moved the telescope tube smoothly up and down. It also locked the tube in position once stopped, because of course, the stepper motor remains powered up, even when not moving.

It was a fun and promising test.  We now need to complete the fly-off, main belt tensioning mechanism and refine the software-based control system.