Spectroscopy & Spectrography

Photos of lens on CCDSPEC under finding/tracking eyepiece and slit

The following are photos from the CCDSPEC finding/tracking eyepiece port.


Under the eyepiece is an inbuilt lens to help focus light onto the finding/tracking eyepiece (removed in this photo below):

The following photos below are magnified photos of the surface of the lens that can be seen in the picture above (the first picture taken through 10mm eyepiece focused on the surface of the lens, the next two through a reticle eyepiece (my Meade XY adjustable illuminated eyepiece likewise focused). I am concerned that there appears to be marks on this lens directly in line of sight of the eyepiece, possibly affecting my ability to observe fainter objects during spectrometry sessions – although worth noting that this will not affect the ability of CCDSPEC to collect light for the spectrometer.as this lens is only for the visual lens port:

Photos below are of the eyepiece above focused on the spectrometer slit:


Spectroscopy Vega, Arcturus, Sadr, failed attempt to take spectrum M57, using CCDSPEC on Sky Watcher Equinox Pro 80mm on Manfrotto mount

Yesterday the sky cleared after raining for a large part of the day. Rhys and I tried to take a spectrum of the Ring Nebula M57 using a new combined flip mirror/off axis guider/hand-guided on Manfrotto video mount. Unfortunately, the experience showed clearly that these nebulae are very faint and we will need to use GOTO power-driven mount to keep the object on the spectroscopy slip whilst taking spectra of these objects.

We did obtain a spectrum of Vega (for calibration), a spectrum of Arcturus and for the first time a spectrum of Sadr.


Sky Watcher Equinox Pro 80mm OTA, with finder scope with illuminated eyepiece, Teleskop Express combined flip mirror/off axis guider and astrometric eyepiece, CCDSPEC with Meade XY adjustable illuminated eyepiece. The experience last night indicated another XY adjustable illuminated eyepiece would be a better choice to the astrometric eyepiece on the combined flip mirror/off axis guider and in fact a flip mirror might be a better choice to the combined flip mirror/off axis guider as will direct more light to the eyepiece (below):

Calibrating spectrum of Vega (using know Vega lines):

Calibration information on Vega lines I have determined previously (see https://roslistonastronomy.uk/re-analysis-of-vega-spectrum-from-4-8-2018):



Vega from 8/6/2019:

Arcturus (spectral class K1.5IIIFe-0.5):


With an apparent visual magnitude of 2.23, Gamma Cygni is among the brighter stars visible in the night sky. The stellar classification of this star is F8 Iab, indicating that it has reached the supergiant stage of its stellar evolution.

We initially guided to Sadr using green lazer on finder show – carefully aligned so point of lazer coincided with CCDSPEC slit – this meant that we did not need to use illuminator on eyepiece – the green lazer was sufficient to show up the guiding reticule on the illuminated eyepiece and a lot fainter than the red light on that eyepiece – we demonstrated that this is an effective method for guiding to fainter stars.

Sadr – this time spectrum without using green lazer:


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!


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 coolcosmos.ipac.caltech.edu/ask/200-Which-planet-spins-the-fastest-)

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 https://www.shelyak.com/planets-rotation/?lang=en for more details.

Identifying spectral lines on Jupiter:

I have attempted to do this using diagram as my source from https://www.researchgate.net/figure/Jupiter-Spectrum-The-white-boxes-represent-the-Fraunhofer-lines-and-colored-boxes_fig2_283695178

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.


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.


Spectroscopy with CCDSPEC 27/4/2019 Vega and Deneb and failed attempt to get M57

Using CCDSPEC spectrometer with Equinox Pro 80mm hand guided on Manfrotto mount.

Calibration pictures – Compact Fluorescent Bulb:

I use the following picture which I prepared using data from Wikipediato help with calibration using CFL bulbs.

Vega – I took spectra of Vega at two points tonight:


Failed attempt to obtain spectra of M57 Ring Nebula (As you can see lines do not line up especially 5800A hydrogen line which is very bright in the nebula = I think what I thought was M57 was in fact another star – I need to get a flip mirror to help finding faint objects for CCDSPEC.