Andrew Thornett

CCDSPEC guiding setup 2/5/2019

This is my proposed CCDSPEC guiding setup based around my Sky Watcher Equinox Pro 80mm refractor. Directly behind the OTA is Teleskop Express Off Axis Guider/Flip Mirror with T2-2″ eyepiece adapter, into which the CCDSPEC is inserted.

Orion XY adjustable 9mm illuminated eyepiece in the CCDSPEC currently and an astrometric illuminated eyepiece in the off axis guider/Flip Mirror, although I intend to later change this for another Orion XY adjustable illuminated eyepiece.

Alongside the main OTA is a finder with helical focused and another illuminated eyepiece. This can be adjusted via its mounting rings to point at the same object in its cross hairs as seen in the CCDSPEC.

Hopefully, this setup will allow me to get a spectrum of M57 Ring Nebula!


Ideas on how to centralise faint objects in CCDSPEC spectrometer slit

The CCDSPEC spectrometer works well on stars and other bright objects such as planets but I am finding it difficult to obtain a spectrum of the Ring Nebula and other fainter more dispersed objects because these cannot be seen in the observing eyepiece on the spectrometer.

I am toying with idea of using a flip mirror but Ed Mann had excellent idea yesterday which I am also considering – mounting a parallel finder scope on the Sky Watcher Equinox 80mm or DS Pro 72mm scopes I use with the CCDSPEC. I can then not only observe fainter objects using this second scope but by aligning it carefully with the slit and cross hairs on the illuminated eyepiece on CCDSPEC I can then use the second scope to guide the scope whilst the spectrum is being taken. This is similar to the method used in astrophotography to guide for  camera.

Might be chance to try this idea out tonight……I can see clouds thinning and Vega has appeared!


Tacking down and trimming edges of shingles in home observatory

It always amazes me how long the start and end of a project takes whilst the middle bit shoots along at pace.

Such is the case with my roofing project on my home observatory.

Following previous posts in which Rhys and I replaced the roof of the log cabin with shingles, today I tacked down the edge of the shingles to the side of the roof and trimmed it off. I bought a new pair garden shears for the latter job!

It took a couple of hours to do what at first sight seemed such a small job.

At least the log cabin can stay as it is now until I get around to the final tasks of adding batons over the edges, trimming the edges of the shingles to match the new batons, and replacing the glittering.

Observant readers of this blog entry will note the streaks of creosote on the inside of the window of the log cabin. Oops! I only coated the outside but some it got inside during process. I will need to empty the back end of the cabin to get to the window to clean it!

I also need to clean off the glittering although if this proves difficult might be easier to replace it……Any one know of good method for cleaning off creosote from plastic and glass?


Guest speaker at RAG tonight 31/5/2019 – ‘Hunting Out Young Stars Project – Citizen Science’ (Dr Dirk Froebrich, Univ. of Kent)

May 31st 2019 – Guest speaker @ RAG ( DF) – ‘Hunting Out Young Stars Project – Citizen Science’ (Dr Dirk Froebrich, Univ. of Kent).

Brilliant lecture tonight from Dr Dirk Froebrich – who drove all the way up from the University of Kent. His Talk was on the Citizen Science Project ‘Hunting Out Young Stars’ – HOYS-CAPS. The concept is fascinating, and has tempted some of us to assist Dr Froebrich and his Team, by contributing to their research – uploading our photos of the night sky.
Contact details for the team can be seen in the photos below from the lecture tonight.



Spectroscopy of Jupiter Andrew 29/5/2019

After Angella and Alan and Chris left tonight, I was packing away my equipment when Jupiter became visible – having previous been obscured by cloud – so I took some quick spectra before it disappeared again.


I thought I could use the above to calculate the speed of rotation of Jupiter at the surface but I was wrong.

Surface speed from my data = 1/4 (Doppler shift in practice needs to be counted 4 times) x 300000km/s (speed of light) x change in wavelength (1200A above)/wavelength (5780A)

= 15570 km/s.

Real speed of rotation: Since Jupiter is a gas planet, it does not rotate as a solid sphere. Jupiter’s equator rotates a bit faster than its polar regions at a speed of 28,273 miles/hour (about 43,000 kilometers/hour). Jupiter’s day varies from 9 hours and 56 minutes around the poles to 9 hours and 50 minutes close to the equator. (From

My own calculations =

Jupiter’s circumference = 439,264 km

Rotation period (length of day in Earth days)
Jupiter’s day = 9.8 Earth hours

So surface speed = 439,264/9.8 =  44,822 km/hour = 12.45 km/s

So I am way out!!

Looking up methodology for calculating surface speed my method is wrong (hence incorrect result) – the real way to do it requires high resolution spectrograph and measure the spectrum at the equator. This spectrum will show a tilt due to doppler shift and from that SINGLE spectrum the speed of rotation at the surface can be calculated from the amount of tilt. See for more details.

Identifying spectral lines on Jupiter:

I have attempted to do this using diagram as my source from

Not sure whether I have identified the correct lines!

Spectroscopy of Vega, Polaris and Deneb with Angella, Alan and Chris Ford 28-29/5/2019

Angela, Alan and Chris Ford came to my house tonight and did a brilliant job calibrating CCDSPEC spectrometer on Equinox Pro 80mm, and hand guiding it to obtain three spectra. Amazing for first ever try!


The team (Chris Ford, Angella, Alan, Andrew):

Angella controls the imaging software while Alan hand guides the scope:

Calibrating the CCDSPEC (Angella, Alan and Chris):

The image below taken with Samsung S7 phone hand held at eyepiece of CCDSPEC spectrometer shows compact fluorescent bulb with spectrometer slit and cross-hairs of illuminated eyepiece:

Compact fluorescent bulb spectrum:

Compact fluorescent bulb spectrum profile in RSPEC after calibration (after calibration shows angstroms of wavelength rather than pixels on x-axis):

Angella used the following graph to calibrate the spectrum of the compact fluorescent bulb – it shows known wavelengths of specific lines in the length (prepared using data in Wikipedia):

Vega (Angella and Alan) – the profile showing the Vega spectrum compared to that of reference library A0V spectrum shows close match with hydrogen Balmer lines:

Polaris (Angella and Alan) – much fainter and more difficult to obtain high quality spectrum tonight – nevertheless some significant lines can be seen to match on the rather noisy spectrum obtained tonight:

Deneb (Angella and Alan):


Spectra from Science Surplus “DIY Spectrometer” comparing sky, tree trunk and CFL bulb, through Sky Watcher Evostar 72ED telescope 28/5/2019

Spectra from DIY Spectrometer comparing sky, tree trunk and CFL bulb, through Sky Watcher Evostar 72ED telescope 28/5/2019. Note that although the x-axis is the same scale for all three graphs, the y-axis scale differs.

Coma beam splitter 1.25″.

Ocean Optics collimating lens at telescope end of fibre optic where enters beam splitter.

I can’t see any meaningful difference between sky and tree trunk spectra but the CFL bulb clearly different.


Creositing the home observatory

I felt it was worth painting a protective layer of creosote on edges of the log cabin home observatory roof before I tacked down the shingles over the edges.

This I did today – weather looked fine.

Just as I finished the rain came down!

The gloves I am wearing are vetinerary gloves designed to allow vets to put their arms in cows’ bottoms up to their elbows! I used them to stop getting creosote on my arms when I was painting the stuff on to the cabin under the eves – worked although creosote dissolved the gloves and I had to keep changing them so good thing that they came in packs of 50!


Review of effectiveness of new illuminated eyepiece for CCDSPEC Spectrometer during observing session 26/5/19

In a previous post I mentioned that I purchased a new illuminated Meade 9mm eyepiece with XY adjustment screws.

I used this new eyepiece on my CCDSPEC spectrometer on my Sky Watcher Equinox Pro 80mm telescope during my observing session 26/5/2019.

Itwas fantastic! When I ensured the star remained in the little illuminated central square as I hand-guided, every time I successfully obtained a spectrum of a star. More problematic with M57 The Ring Nebula but this was due to this objects relative faintness and difficulty of swing it at all with any time finder eyepiece in CCDSPEC. That is something I need to find a solution to.