RSPEC Spectrum Analysis Software

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):


Spectroscopy of Moon, Capella and Sirius in Lichfield 18-19/2/2019 – Andrew Thornett & Nick Rufo – CCDSPEC slit-based spectroscope and Star Analyser spectroscopy grating

Last night was predicted to be clear all night. The Moon was bright, so it seemed to be a good opportunity to do something other than observing. Nick and I are both interested in spectroscopy so he bought around his Star Analyser on his camera and I took outside my Sky Watcher 120mm Equinox on EQ6 mount with CCDSPEC spectroscope. Of course, it did not turn out to be clear all night but nevertheless Nick and I were able to do some good work & enjoy ourselves……apart from when I dropped his camera lens on the floor – Andy strikes again – ahhh!

The Star Analyser has advantage of being quick to set up whereas the Equinox/EQ6/CCDSPEC was lot of faff to set up – Nick was photographing spectra well before me!

Successful procedure for aligning EQ6 mount/Sky Watcher Equinox 120mm telescope/CCDSPEC & taking spectra:

In fact, last night was a very positive experience for me because I got the procedure of taking spectra with tracking mount working properly for first time – hitherto my spectra have been on undriven Manfrotto mount with Sky Watcher Equinox 80mm.

Process that worked last night was:

  1. Balance EQ6 using heaviest eyepiece I have – 20mm Explore Scientific 100 degree eyepiece in 2″ diagonal – last night I also had finder scope for 120mm on scope and also Ed Mann’s wonderful powered and heated laser finder. I used 2 counterweights on the EQ6. Do NOT pull dew shield out during balance process.
  2. Perform 3 star alignment using the eyepiece. This is NOT easy to do with CCDSPEC eyepiece so use the heavy Explore Scientific 20mm eyepiece for the 3 star alignment. Need finder and laser to help with alignment.
  3. Exchange eyepiece for CCDSPEC. In CCDSPEC use illuminated reticule eyepiece – this has cross hairs that enclose the slit at centre helping to get stars on slit. Focus CCDSPEC using its eyepiece so star or Moon even better focused on slit – this involves racking focuser right out – hence why balance an issue as moment on the balance point of mount is changed – so need to use heavy eyepiece initially. Pulling dew shield out at this point helps with balance of scope as eyepiece exchanged for CCDSPEC.
  4. Slew to object of interest. Laser pointer and finder help if 3 star alignment not perfect.
  5. Use illuminated eyepiece to slew object onto slit as likely to be slightly off in field of view.
  6. Once object hits slit it will spread out from point light source into tiny spectrum.
  7. Take photo of spectrum using QHY6 camera on CCDSPEC and Nebulosity software – choose ASCOM camera in camera choice drop down list and then QHY6 camera in drop down menu that follows in Nebulosity from choosing ASCOM camera.
  8. Analyse spectrum in RSPEC.

Spectrum of the Moon:

The following is a photo of spectrum on Star Analyser showing the Moon to the left and its spectrum to the right taken by Nick with his Canon camera on undriven mount with Star Analyser grating. I love this photo – which can only be done with the Star Analyser – on the CCDSPEC you don’t see the Moon in the same shot!

In the following image, I have graphed the spectrum taken with CCDSPEC of the Moon last night against a reference solar spectrum (CCDSPEC pointed at cloudy sky in day) taken by myself 1/8/2018 (below). The spectrum of the Moon as taken by the QHY6 camera is shown on the left and a graph of this in RSPEC on the right, together with the reference solar spectrum. It shows that the lines on the spectrum from the Moon match those on the spectrum from the Sun – this is because the spectrum from the Moon is in fact the spectrum of reflected sunlight bouncing off the Moon which does little to alter it as it has no significant atmosphere.

Spectrum of Capella:

I was really pleased when I could slew the EQ6 to Capella and within two attempts get spectrum of this star. The laser pointer REALLY helped to compensate for problems in my poor 3-star alignment.

In the screenshot from RSPEC below, Capella’s spectrum is on the left as it comes out of the QHY6 and on the right this spectrum is graphed against the same solar spectrum as above. Some but not all of the lines match, showing that the two stars differ in composition.

Spectrum of Sirius:

Nick took a spectrum of Sirius using his Canon DSLR/Star Analyser/Canon kit lens:

Some lines are visible in centre of graph (dips) – to determine what these are we would need to calibrate the graph. Turned out calibrating the Star Analyser spectra requires a bit more work on the light used – my CCDSPEC slit easily uses just about any light with clear identifiable lines but we need to point or at least narrow light source for the Star Analyser which we did not have available tonight……a job for Nick to make himself one!

Calibrating the spectra:

I have not got around to doing this yet – but this process involves identifying lines with known wavelengths so that the pixel measurements above can be replaced with wavelengths.

To this end, I took a spectrum last night of a 12V Compact Fluorescent bulb using same set-up as above. For some reason the graph is the wrong way around and needs to be inverted left-right but I seem to be having difficulties getting RSPEC to do this on the data set for this spectrum, hence why I have not yet calibrated the above spectra!

I will be able to identify the lines using this graph below:

Using the “subtract background” function in RSPEC Software to bring the baseline down towards zero on Altair spectrum from 10/10/2018

Following my recent post:

Attempt to generate instrument response curve in RSPEC software for CCDSPEC using Altair spectrum from 10/10/2018

Peter Hill asked me whether I had used the “subtract background” option in RSPEC to bring the baseline down towards zero on the spectrum – I had not done it and did not know what to do so I looked it up and here is the difference it makes……(below)

A dramatic improvement! Thanks Pete for the advice!


WITHOUT the “subtract background” feature being used (below):

WITH the “subtract background” feature being used (below):

Spectroscopy of Altair (and Vega) in Lichfield, UK 11/10/2018, using CCDSPEC, Sky Watcher Equinox Pro 80mm OTA on Manfrotto manual mount

A new star tonight for me – Altair! I have not taken a spectrum of this star before. Being also an A type star (A7V), it was going to be similar to Vega (A0V). Therefore, I took a spectrum of Vega for comparison too..

Taken using CCDSPEC spectrometer with Sky Watcher Equinox Pro 800mm Telescope on alt-az undriven Manfrotto mount – hand-guided for 50 second exposures.

RSPEC software has some great reference spectra which I was able to use to calibrate these images this evening. Cross checked using my own image of Vega as reference spectrum.

Note Vega = A0V spectral type

Altair = A7V spectral type


The post below follows on from the above post:

Attempt to generate instrument response curve in RSPEC software for CCDSPEC using Altair spectrum from 10/10/2018


Attempting to calibrate RELCO Starter against 12V Compact Fluorescent Lamp in order to work out the wavelengths of the main lines on RELCO spectrum

Today, I have had a go at calibrating the homemade RELCO Starter bulb calibration lamp I made against 12V compact fluorescent lamp bulb in order to determine the wavelengths of the main lines on the CCDSPEC spectrum of the RELCO bulb.

Download calibration files from analysis by clicking on link below – calibration files RELCO vs CFL CCDSPEC no telescope 30/9/2018:

Spectrum RELCO Starter on CCDSPEC without telescope 300918

Also look at to find out what happened when I tried to compare the lines I identified below with the atlas of lines from – sadly they don’t seem to match!


RELCO Starter Bulb spectrum taken with CCDSPEC Spectrometer (below):

Spectrum of compact fluorescent light bulb taken with CCDSPEC (below):

Graphing both above spectra together:

Calibrating spectra of both RELCO and CFL using above two lines in RSPEC gives following calibrated spectra:

The following is my final labelled image showing main lines on RELCO starter bulb spectrum (below):

How to process spectra recorded from the Science Surplus “DIY Spectrometer” using the “Spectrum Studio” software in either Microsoft Excel, RSPEC or VSPEC software

How to process spectra recorded from the “DIY Spectrometer” using the “Spectrum Studio” software in either Microsoft Excel, RSPEC or VSPEC software.

The following is my summary and my own screenshots of the process using a solar spectrum I took using the DIY Spectrometer. I am indebted to Jeffrey L. Hopkins’ excellent book for teaching me about the process “Using commercial amateur astronomical spectrographs” and is the only resource that I know of that explains how to do this.

Processing the results from the DIY spectrometer in Excel, RSPEC, VSPEC:

Spectrum line profiles generated from the DIY spectrometer using its own software Spectrum Studio can be saved as a CSV file. Later we need to convert it in to a text file, once we have manipulated it in Micosoft Excel or Open Office or other similar spreadsheet programme.

Saving profiles from Spectrum Studio:

As shown in the screenshots above, Spectrum Studio automatically saves as CSV file which can then be directly loaded into Excel.

The CSV file produced includes a header with the scan date which uses the computers date and time, integration time which is the same as exposure time, and number of averages.

The following screenshot shows the Spectrum Studio CSV file as generated by Spectrum Studio opened in Microsoft Excel. I have highlighted the header:

Five columns of data will be found below this header.

Under the five columns are 2047 rows of data corresponding to the 2047 pixels on the linear CCD chip. Each row has an associated column for pixel number, wavelength in nanometres, sum, average, background. If the spectrum has been calibrated then the pixel number and wavelength will be the same.

The CSV file that is been saved above can be opened in Excel. Only two columns are needed for further analysis – the pixel number and the sum.

The following screenshot shows the Spectrum Studio CSV file opened in Excel with the Pixel Number and Sum columns highlighted – these are the two columns that need to be kept in order to open the file in RSPEC/VSPEC – other columns are deleted as is the header:

To create a line profile in Excel or Open Office or other similar spreadsheet programme, select these two columns and choose the desired graph from the options open to you in the spreadsheet software. The data files of multiple columns of ADU counts, Microsoft excel can be used to produce another column which is the sum of those counts for a given pixel position. That sum and pixel position can be used to create the line profile graph. The pixel number versus the wavelength can be determined and a new column created that shows the wavelength for each pixel position. The sum column and the new wavelength column can then be used to create a wavelength calibrated line profile graph. Such a graph would be very similar to the one that appears on the DIY spectrograph’s own spectrum software when you take spectrum.

Microsoft Excel helps allows you to manipulate the file so that it can be loaded in RSPEC/VSPEC but programmes such as RSPEC or VSPEC are easy to use if you want to process the spectrum in practice.

In order to open the text file from the DIY spectrograph spectrum in RSPEC or VSPEC, some changes need to be made to this text file. Open it in Microsoft Excel and then:

1. Delete the header data
2. Delete the column titles
3. Delete all columns except pixel number and sum
4. Save the resulting file as a text file. It does not matter from my own experience whether you save as Unicode text file or as tab-delimited – both with open in RSPEC/VPSEC.
5. Change the extension from .txt to .dat

The file can now be opened in RSPEC or VSPEC.

This file is not an image file any longer so it must be opened as a line profile .dat file.

Opening profile in RSPEC:


Once opened in RSPEC or VSPEC the profile can then be wavelength calibrated and further processed.