Multiple stars, 17 Lyrae and Aquila.

slim chance to get there before the huge Moon bleached out the sky.Aquila is well placed for comfy seated for observing. Altair is a fine wide binary. Attention to some multiple and binary stars. It’s a wonder that larger apertures can catch faint magnitude stars. One numerical change in magnitude is a change of x2.51 in magnitude. However this is exponential, 2 magnitude difference is 2.51 squared ,3 is 2.51 to the power of three.

17 Lyrae gives a wonderful high power view of this multiple. The companions are a manageable search.(SAO 67835) A is 2.2 x Sol diameter.

23 Aquilae is an eruptive variable giving a yellow and astounding blue companion. A huge A has a diameter of 22.3 Sol. Separated by 364 AU. (SAO 124487)

28 Aquilae is a pulsating variable, the A being x3.6 Sol diameter.(SAO 104722)

Now for a very very fast moving star, 31 Aquilae. There are 4 stars here not gravitationally linked . Herschel did not include it in his list of doubles as A was well away from other stars.(SAO 104807)

Hoping next time out to catch the low field view that includes Σ2547, Σ2545, LV21 and Σ2541. Clear skies ! Nick.

Stargazing in Skopelos, Greece in August 2018

Hi folks,

 

We’ve just got back from a holiday in Greece, and as part of a local festival of music, dance and culture, I met a really nice chap George (Giorgiu),who had set up a viewing area for the public to see the Moon (Selene in Greek), Mars (Aris), Jupiter (DIas) and Saturn (Kronos). That’s George checking the view of Saturn in the second photo

He has the first, and only, observatory on the island and it’s in a great location away from the town lights (the lat long coordinates are on the poster in the first picture)

He was interested in what we are doing too so I’ll drop him a line and hopefully get to see his obsy next time

Taken with NightCap. Long Exposure mode, 7.12 second exposure, 1/3s shutter speed.This was the night of the full moon (Sun 26th August 2018). Mars can be seen above the right hand set of masts although the photo doesn’t show very well here and I don’t know how to make it zoomable

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.

Resources and video tutorials online for use of Science Surplus DIY Spectrometer

The following resources are available on-line:

Company webpage:

Main webpage: http://www.science-surplus.com/products/spectrometers

Resources for Spectrometer: http://www.science-surplus.com/products/spectrometers/spectrometer-resources

Youtube video showing recording spectra from specific metals is sparks and also gives some detail on use of ability in the software to explore specific atomic lines on the spectra:

Other we based resources:

http://redlum.xohp.pagesperso-orange.fr/electronics/spectrometer.html

http://www.thepulsar.be/article/science-surplus-spectrophotometer-review/

https://www.photonlexicon.com/forums/showthread.php/24623-Science-surplus-spectrometer-calibration-help-needed

https://stargazerslounge.com/topic/204245-diy-spectrometer-first-light/

CCDSPEC Spectrometer/CCDSPEC Spectroscope/CCDSPEC Spectrograph/Science Surplus DIY Spectrometer

Click on following links to view posts on amateur astronomical spectroscopy on the website of Rosliston Astronomy Group:

All relevant posts:

https://roslistonastronomy.uk/category/spectroscopy

Posts related to the use of the CCDSPEC Spectrometer made by Ken Elliott:

https://roslistonastronomy.uk/category/spectroscopy/ccdspec-spectrometer

Posts related to the use of the Science Surplus DIY Spectrometer:

https://roslistonastronomy.uk/category/spectroscopy/diy-spectrometer

Does perspex effectively change solar spectrum or compact fluorescent light spectrum recorded with CCDSPEC spectrometer?

I mentioned at the RAG meeting on Friday evening that I was making a portable calibration light using a compact fluorescent bulb in a desk stand and that I was making a Perspex diffuser to go in front of it.

Lee wondered whether the Perspex would change the recorded spectrum due to its absorption characteristics. I am very grateful to Lee for pointing out this possibility as it clearly needs to be checked, especially as being able to know the exact wavelengths of the peaks on the spectrum produced by the bulb is vital to the calibration process and if these change as a result of the Perspex then this will mean that I will need to be careful using this material during the calibration process.

I have this tested this hypothesis this evening. If the Perspex does change the spectrum then I will know that it will limit the use of the lamp as a calibration device.

My test below used the solar spectrum initially, followed by use of same compact fluorescent bulb as being used in my portable calibration light.

Result of these tests = Perspex sheet reduces intensity but does not effect spectrum – therefore can be used as diffuser in front of calibration light without problems.

Andy

Solar spectrum taken by pointing CCDSPEC spectrometer out of window (not attached to a telescope) – this spectrum is without anything in front of the CCDSPEC spectrometer:

The following spectrum was taken as above but this time I placed the piece of Perspex I intend to use as the diffuser on the new portable compact fluorescent bulb calibration lamp in front of the CCDSPEC touching the 2 inch eyepiece adapter so that very little light could get into the CCDSPEC without going through the Perspex (below):

In the following image, I have compared the above two spectra and added some lines to demonstrate that absorption lines are essentially unchanged between the two:

The above spectra are not calibrated on x-axis. The following is a repeat of the image with Perspex in front of the CCDSPEC but this time calibrated to give wavelength on x-axis in nanometres (nm):

The above shows that the solar spectrum as shown on CCDSPEC stretches from essentially 400nm to 750nm – this will be limited by the instrument’s response as the solar spectrum extends either side of this.

The following graph shows typical transmission characteristics of variety of plastic materials including acrylic from 200-1200nm:

From the above spectrum, it is unlikely that plastics make little difference to the spectrum of light over the range of wavelengths covered by CCDSPEC, and this appears to be born out by my solar spectra today.

Spectrum from CCDSPEC pointed at desk lamp with compact fluorescent bulb WITHOUT Perspex between them (darkened room, below):

Repeating above but this time placing Perspex over end of CCDSPEC – compact fluorescent bulb, darkened room:

Perspex can be seen to reduce intensity but does not meaningfully change the spectrum so will not adversely affect the ability of the Perspex covered light to act as calibration instrument. The reason that I want to add perspex in front of the calibration light is to act as a diffuser and give even illumination (the Perspex has appropriate surface to act as diffuser).

Solar spectrum taken at LRO 26/8/2018 using DIY Spectrometer

Having calibrated my DIY Spectrometer, I took a solar spectrum by pointing the telescope at the cloudy sky outside LRO.

I have compared the spectrum below to a published spectrum.

It shows many prominent lines. Unfortunately, it also shows that my calibration was off – the red lines should be vertical!!!

Andy