My Astronomy




My Telescopes

My Main Telescope - C14 and Paramount ME

My new Paramount MyT and 8-inch Ritchey-Chretien Telescope

MyT Hand Controller

My Meade 12 inch SCT on a CGEM (Classic) Mount

My 4 inch Meade Refractor with Sky Watcher Guidescope and ZWO camera on a CGEM (Classic) Mount

Skywatcher Star Adventurer Mount with Canon 40D


My Solar setup using a DSLR and Mylar Filter on my ETX90

DSLR attached to ETX90. LiveView image of 2015 partial eclipse on Canon 40D

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 I try to log my observing and related activities in a regular blog - sometimes there will be a delay but I usually catch up. An index of all my blogs is on the main menu at the top of the page with daily, weekly or monthly views. My Twitter feed is below. I am also interested in photograping wildlife when I can and there is a menu option above to look at some of my images. I try to keep the news feeds from relevant astronomical sources up to date and you will need to scroll down to find these.

The Celestron 14 is mounted on a Paramount ME that I have been using for about 10 years now - you can see that it is mounted on a tripod so is a portable set up. I still manage to transport it on my own and set it all up even though I have just turned 70! It will run for hours centering galaxies in the 12 minute field even when tripod mounted.


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« Spectroscopy Part 4 - Balmer Line identification in Vega | Main | Spectroscopy Part 2 - Spectrum of Vega »

Spectroscopy Part 3 - Vega Spectrum Calibration

Continued from Part 2

I am working on my previous 135mm lens Vega spectrum today using RSpec and first show the Vega image adjacent to the generated raw profile.

To calibrate the spectrum I need two reference points. The first one is easy. The star image has passed directly through the grating without deflection and so zero Angstroms corresponds to the pixel position of the star as shown below.


The second reference relates to the Balmer Series Hydrogen Beta line which is clearly visible in the raw spectrum and corresponds to a wavelength of 486.1 nm or 4861 Angstroms. I entered this value which corresponds to the pixel position of 2722 pixels on the Canon chip.

This is how I calculated the Hydrogen Beta line wavelength for the above calibration value - as shown in the extract from my spreadsheet below.

 The Balmer series of lines are all caused by an electron transition between orbit 2 and higher orbits. For the Beta line it is between orbits 2 and 4.

Once the x-axis changes to Angstroms, the number of Angstroms per pixel is shown - in this case it is 4.3 A/pixel. Now that is known,  in future I will only need to set the zero point to produce a calibrated profile on any star using the 135mm and grating with the same camera.




I will continue with this in Part 4.