Spectroscopy - Where should I start?

[Owmuchonomy]

I am very interested in attempting some amateur spectroscopy.  Could those much more experienced give me a pointer as to where to start researching this part of the hobby.  I don't expect to be told how to do it but will research thoroughly.  My current (observational and imaging) equipment is listed in my signature and I have a permanent obsy set up.  Aside from the two cameras listed (174MM and Lodestar mono) I do have a DSLR too (5dMkIII).  I have also completed a couple of online courses which include Spectroscopy as modules such as the Uni of North Carolina excellent astro course.  I have a scientific background (PhD in Pharmacology).

One thing I will say is that I am totally MAC. I hate PCs with a passion so if that creates a barrier for software choices then I will be disappointed. That said I have DSS and AS!2 running smoothly via Wineskin on my desktop.

I look forward to your hints and tips. Thanks very much.

[Oddsocks]

Chris.

I noticed no one had replied yet and I am no expert but here is how I started.

I began with an old Image Source firewire mono video cam and the Paton Hawksley Star Analyser 100 diffraction grating: http://www.patonhawksley.co.uk/staranalyser.html

I use Windows in a permanent observatory since I need ASCOM to interface with all the different software packages but all my post processing is done on Mac.

For acquisition as long as you can find a sensitive webcam with smallish pixels that has native Mac drivers then you will be able to capture video of brighter objects directly onto the Mac. Depending which make of DSLR you own you may also be able to drive and acquire images direct to the Mac with that.

For analysing the captured data there are several popular packages, RSPEC, which is paid for and which I started with: http://www.rspec-astro.com, or BASS project which is free, (the download link moves around quite often so you have to access the Yahoo groups quite often to keep tabs but currently a document detailing the download links and revision status can be found here: https://dl.dropboxusercontent.com/u/87095951/Spectro/BASS Project/0.0.1.0/0.0.1.9/1.9.3/BASS Project Release Notes 1.9.3.pdf . The Yahoo group for BASS is here:  https://uk.groups.yahoo.com/neo/groups/astrobodger/info .

Then there is:

Visual SPEC: http://www.astrosurf.com/vdesnoux/

ISIS:  http://www.astrosurf.com/buil/isis/isis_en.htm,

IRIS: http://www.astrosurf.com/buil/us/iris/iris.htm

IRAF: http://iraf.noao.edu/

SpcAudace: http://bmauclaire.free.fr/spcaudace/

and

Spectroscopy Analysis Software: http://www.thewhightstuff.co.uk/?page_id=128

 

There is a useful webpage maintained by the ASSA that lists much of the relevant information sources for beginners in spectroscopy: http://assa.saao.ac.za/sections/photometry-spectroscopy/spectroscopy/

Looking around the forums I get the impression that the free BASS software is the most widely used amongst amateurs.

Of these only IRAF and SpcAudace run natively on Mac OS X the others are Windows programs.  In my case I run a couple of Windows virtual machines in Parallels desktop on my Mac (Win 7 64bit Pro and Win 10 64 bit) and I also have other Astro post processing software that only runs on Windows, XCalibrator, Registar, Maxim, Registax, Auotostakert etc etc so this was a necessary evil for me and at least the drag and drop facility with Parallels means I can easily move between PixInsight and Photoshop CS6 on the Mac and whichever Windows virtual machine I am using. RSPEC (Windows) is easy to use as a jumping in point and BASS (Windows) is brilliant as well as being free.

The Paton Hawksley 100 Star Analyser is a really easy and inexpensive place to start and I spent my first couple of years getting to know how to use the software, RSPEC and more lately BASS, you are limited to the brighter stars and the resolution of the spectra is quite low but this is not a toy and quite useful work can be done with it. The SA 100 can be obtained for less than £100: http://www.365astronomy.com/Star-Analyser-100.html and you might already have a suitable webcam or DSLR you can use.

If you get hooked then a pro / semi-pro slit spectrometer is the next step and then you are looking into possibly thousands of pounds of outlay, not just for the spectrometer but for the high quality mount and guiding you need to keep the target star tracking for hours on the slit, you already have a good mount and guide camera so you are half way there already.

I began building my own self guiding photo-spectrometer two years ago using salvaged parts from a couple of CD writers to scan a phototransistor by a moving mirror set behind a servo driven variable width slit, the hardware was fairly easy once I invested in a milling machine but I have struggled with the weight and have recently begun a redesign with much of the chassis being replaced with 3D printed parts. The software is proving a bigger challenge, much has changed since my only software writing experience with UNIX and VENIX in the 1980s but I have just bought a Raspberry Pi and begun to learn Python so perhaps one day I will have it finished....

If you want an off the shelf product then the Shelyak Alpy Spectrograph is popular: http://www.iankingimaging.com/show_product.php?id=1461, it is a modular product and by the time you include the guiding module and calibration module you will easily be past a £2000 spend.

The high price of ready made Spectrometers drives many to self build, an amateur astronomer at my local astro society made one from plywood and razor blades for the slit and he gets as good as results with that (using a DSLR) as many others achieve with the semi-pro ready made stuff so it can be done on a budget provided you have the tenacity.

If you do get into Spectrometry it opens up more observing opportunities, especially when the conditions are too poor for conventional astro imaging due to intermittent cloud cover or an intrusive moon, you can always find a gap somewhere to grab a few minutes of video with a diffraction grating and processing that video will give you another hour or two of enjoyment!

William.

[Owmuchonomy]

William @Oddsocks, that is truly a comprehensive response and exceeds my expectations.  Thank you very much.  I tested my kit out on the Paton Hawklsey configuration page for the Staranalyser 100.  I got 3 green OK boxes by using a 10mm spacer on my ASI 174MM and coupled to my 9.25SCT at f/10.  So that looks a good start.  Regarding software I can run Autostakkert for example on my MAC no problem.  I'm happy to try one of the spectroscopy packages in the same way via Wineskin just to see if it runs.  If not, I do have access to a dreaded PC.  I presume a short video then stacked is what the spectroscopy software is requiring?  Please correct me if I am wrong. Your skills at self build are very impressive.  I wish I understood half of what you have achieved.

[Merlin66]

Chris,

William has given a pretty good overview of "Spectroscopy 101"

The Star Analyser provides a great introduction and will allow you to gain experience in spectral processing....

Most of the spectral processing software will handle raw files in FITS format.

I use and recommend BASS Project.

Check out Christian Buil's website for information on DIY spectroscopes, and much, much more.

http://www.astrosurf.com/buil/spectrographs.htm

 

[Oddsocks]

7 hours ago, Owmuchonomy said:

I presume a short video then stacked is what the spectroscopy software is requiring?

Depends on the software Chris.

In RSPEC it takes the raw video file and does the frame stacking internally, or you could import a preprocessed single image in several different choices of format. I think RSPEC used to have a demo licence and some video tutorials available on their website.

For other spectroscopy packages you could stack a video file in Registax or AutoStakkert and then import the single output frame as uncompressed TIFF or PNG. If you have PixInsight you can convert TIFF, PNG or RAW Canon/Nikon directly into FIT for those spectroscopy packages that only work with FIT files.

As Merlin states if you have a dedicated astro camera that outputs in FIT format you can use that as a single frame directly into BASS, or, you can manually combine single FIT frames in Maxim, probably DSS too although I have not tried that, PixInsight etc.

William.

[Merlin66]

For what its worth, I use AstroArt for all my camera controls (as well as guiding), image acquisition and all the pre-processing.

For the spectroheliograph project I'm using the ASI174 under FireCapture.

 

 

[Owmuchonomy]

Thanks all.  Very informative. I use @JamesF oaCapture with my ASI174 which can capture video in pretty much any format.  Not sure about single output frames.  So I might start there and see how I get on.

Does anyone know the depth of the 1.25" spacer on the PHEL website http://www.patonhawksley.co.uk/accessories.html?

[ejp1684]

Some great advice here. I tried all the software analysis programs and now use BASS project software. Once you get into it, there's an amazing amount of stuff you can do with the Star Analyser 100.

Eric.

[Merlin66]

Chris,

The spacers are 10mm.

 

[Dave In Vermont]

+10 For the StarAnalyzer from PatonHawksley. And here's a very good book to go with:

https://www.amazon.com/Grating-Spectroscopes-Patrick-Practical-Astronomy/dp/1461413966

You should find one near you.

Enjoy!

Dave

[Owmuchonomy]

1 hour ago, Dave In Vermont said:

+10 For the StarAnalyzer from PatonHawksley. And here's a very good book to go with:

https://www.amazon.com/Grating-Spectroscopes-Patrick-Practical-Astronomy/dp/1461413966

You should find one near you.

Enjoy!

Dave

Hi Dave, yes I already ordered the StarAnalyser 100 and spacer. Cheers.  I will check the book out too.

[Owmuchonomy]

So the stuff has arrived and the book arrives tomorrow. I joined the BASS Yahoo group and have been accepted. However, the user group interface does nothing,. The menus don't work nor do the links so I can't get to the software. Any thoughts. I've contacted the organiser but as yet no reply.

[Merlin66]

Chris,

I've just sent you a message with the BASS Project download details.

 

[Whirlwind]

One other thing to note.  With spectroscopy you don't have to be so bothered about poor transparency conditions which might stop other forms of astroimaging.  All you are trying to do is build up the signal to noise from the star so even if there is a lot of high haze, as long as you can still guide accurately and you are observing a bright star then you can carry on.  Poor seeing can also be less of an issue especially when you start using slits to target one particular star (all you are doing again is reducing the signal to your spectra).

[Owmuchonomy]

On 9/21/2016 at 22:01, Merlin66 said:

Chris,

I've just sent you a message with the BASS Project download details.

 

Thanks very much I will check it out.  My concern is that if the user group is not working, which it isn't for me, then I won't be able to use it for information and support.

[Merlin66]

Chris,

I'm sure John and all the others who use BASS Project can assist you.

I can' t final any problems with the forum...is it your settings in internet which are affecting Yahoo access.. Do other Yahoo sites work OK?

 

[Owmuchonomy]

27 minutes ago, Merlin66 said:

Chris,

I'm sure John and all the others who use BASS Project can assist you.

I can' t final any problems with the forum...is it your settings in internet which are affecting Yahoo access.. Do other Yahoo sites work OK?

 

Well, possibly yes, but everything else works.  My Yahoo mail works ok but not the forum.  What settings are you referring to?

[Merlin66]

Chris,

Just checking if you can successfully access any other Yahoo groups.

 

[Owmuchonomy]

On 9/23/2016 at 10:16, Merlin66 said:

Chris,

Just checking if you can successfully access any other Yahoo groups.

 

Thanks very much for trying to help.  I have been through the help process, enabled Java plug-ins, enabled pop ups etc., etc.  The BASS Yahoo user group is functionless on my system.  My other Yahoo stuff seems fine.  I haven't heard back from the administrator yet.

On a more positive note I have my Staranalyser 100, locking ring and spacer ready to try.  I have also read the salient parts of Ken Harrison's book.  I need to run through the maths again but it seems that I could use either my SCT 9.25" or even my ED80 to a point although the star size is a bit low for the pixel size of the 174 and I guess there will be more curvature.  It's fun learning about it though but I need to go and capture a spectrum now and get some software.

[jnp]

Hi Chris,

I'm the author of BASS Project. I haven't been on SGL for quite a while.  

What browser (& version) are you using. If you haven't already, try Chrome?

Not sure what links Ken provided. Let me know if you still need direct links to the documentation and software. The latest version is 1.9.4. Drop me a line, with more details on the issues, if you are still stuck. You can also try post to the group by sending your email to astrobodger@yahoogroups.co.uk

regards

John 

[Owmuchonomy]

Hi John I use Safari on MAC OS X El Capitan.  Having checked various help forums it seems to have been a bit of a cross browser issue since May 2016.  There is no simple or single solution it appears.  Some administrators are also having issues.

[Oddsocks]

3 hours ago, Owmuchonomy said:

Hi John I use Safari on MAC OS X El Capitan.  Having checked various help forums it seems to have been a bit of a cross browser issue since May 2016.  There is no simple or single solution it appears.  Some administrators are also having issues.

Hi Chris.

I am using Safari, just updated to Sierra but previously with El Capitan and can access BASS Yahoo group and other Yahoo groups without any issues but there are known problems with Safari and a common "fix" for when some sites no longer respond correctly.

If you have not already done this try the following:

Open Safari and in Safari Preferences click on the "Advanced" icon and then place a tick in the "Show Develop menu in the menu bar" then close the preferences tab. and close Safari.

Open Safari again, in the top of screen menu you will now see the "Develop" sub menu available, click on this to open the develop tools and look for the item "Empty Caches", click on this to clear all stored web pages from the browser memory, note this does not remove your bookmarks or passwords just the archived pages that are used to speed up page calls and the little website icons that appear in the bookmarks folders (these will reappear as you revisit the webpages or open the bookmarks tab from the top menu and leave the browser idle but open for a hour or so).

Close Safari and wait a moment before reopening then try visiting the BASS yahoo webpage again and see if the page links are now working.

When the website designer builds a website they can choose to force a page refresh and ignore cached pages by a coding command but depending where they place the instruction not all browsers will follow this and they just pull up the cached page from memory and rely on the user to use the "refresh" icon in the website address bar, if you are not aware of this you just end up looking at old webpages.

I now clear the caches monthly as it speeds up the browser and stops a lot of these page faults.

Safari is not a perfect browser and I have lots of problems using online banking with it so I have both Firefox and Chrome loaded as well with Firefox being the most reliable and seemingly secure for on-line banking since Chrome will not work with the Rapport browser security software that RBS provides and requires it's customers to use. If I want to see astro pictures on-line I use Chrome because it is the only browser that displays images that are true to the sRGB standard so you see the image the way the creator intends and not contrast or gamma enhanced.

HTH

William.

 

[Owmuchonomy]

Thanks William. I will certainly give that a try. Much appreciated.

[Owmuchonomy]

1 hour ago, Oddsocks said:

Open Safari again, in the top of screen menu you will now see the "Develop" sub menu available, click on this to open the develop tools and look for the item "Empty Caches", click on this to clear all stored web pages from the browser memory, note this does not remove your bookmarks or passwords just the archived pages that are used to speed up page calls and the little website icons that appear in the bookmarks folders (these will reappear as you revisit the webpages or open the bookmarks tab from the top menu and leave the browser idle but open for a hour or so).

Close Safari and wait a moment before reopening then try visiting the BASS yahoo webpage again and see if the page links are now working.

Sorry to report that this procedure did not work but thanks for the suggestion.

[Oddsocks]

3 hours ago, Owmuchonomy said:

Sorry to report that this procedure did not work but thanks for the suggestion.

Thats a pain...

When you are on the BASS Yahoo groups page do you see your Yahoo login name in the purple banner at the top of the page next to the e-mail logo and have you logged out and back into Yahoo to update your group membership since requesting membership to the BASS group......for me I don't see new additions to Yahoo groups unless I log out of Yahoo and back in and also have to do this if something has changed with my Mac i.e. after updating to Safari v10.10 a few weeks ago and again after updating to OSX Sierra just last week I had to logout of Yahoo and back in which generates the popup message "We haven't seen you log in from this device before, choose how to obtain your verification code"...or something like that, can't remember the exact wording, once I log back in I then see any new groups that I have joined.

If this does not fix it for you and the same access problem exists with Firefox or Chrome then the problem can not be with your mac and must be with Yahoo groups which is going to need Yahoo tech support to resolve.

William.