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Walking on the Moon

Spectroscopy set-up

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I have just finished commissioning my new spectroscopy set up.

It is based on a Paramount ME and The Sky X Pro, Orion Optics ODK16, FLI Atlas focuser, Inovations Foresight ONAG, and Shelyak Instruments Fiber guide head. In addition there are 4 cameras an FLI ML8300 for target acquisition and guiding, Atik414 Ex for the low resolution spectrograph, Starlight Express SXVR6400 for the medium resolution spectrograph and an Imaging Source USB camera to monitor the fiber entrance.

The set-up is very stable giving reliable pointing with a PSD of 13 arc seconds. The ONAG passes the infrared below 750nm to the guide camera which allows me to plate solve and hence automate the collection of spectra. The rest is reflected to the Fiber guide head. After the plate solve the mount is jogged to place the target star onto the 75 micron hole which couples to a 50 micron fiber which feeds the spectrographs. Not so simple at a focal length 2720mm!

This arrangement allows me to leave the system untouched while switching between low and medium resolution spectrographs. Three fiber cables (orange) can be seen on the image two are for the spectrographs and the third takes calibration light from a Argon Thorium lamp and passes it on via the guide head to the spectrograph.

The automated runs are done via Java scripts controlling The Sky X which allows me to keep warn inside while the system does the work.

The low resolution spectrograph (R ~ 350) is complete, see below, but the medium res one (R ~8000) is still under construction and a high res spectrograph (R- 20000) being designed.

I realise most of you are imagers or visual observers but thought you might find this of some interest.

Regards Andrew


Very low res.jpg

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Glorious. I have just started on that road, but of significantly more modest means to begin with. RC6, 414ex and currently a StarAnalyser, but hoping to pick up an Alpy early next year. Your setup is something to inspire! What targets or projects have you/are you working on with this?

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Glad to see you are taking up spectroscopy Matt, as you can see it can become all consuming. The Aply is a fine instrument and the Star Analyser a good learning tool.

I have to admit I have collected the kit over many years! The lenses in the Low Resolution spectrograph are at least 15 years old. The ML8300 is from the days when I did astrophotography and the Imaging Source camera from solar studies.

I intend to use the R~350 spectrograph to continue the Be search work I did with the old kit (see here http://www.astrosurf.com/aras/be_candidate/auto-be-candidate.htm ). I still need to satisfy myself the resolution is high enough but if not it is a simple job to change the grating.

The R ~ 8000 spectrograph will allow me to follow up on any new discoveries from the Be search. It will also allow me to study spectroscopic binaries and do RV line measurements on giant stars like Rho Cass. To this end it will be in a temperature controlled environment. It is far too massive to be attached to the telescope.

The R ~ 20000 will be dedicated to H alpha line studies of Be and other stars of interest.

The flexibility of just changing over the fiber cables will allow me to mix and match as the weather, targets and mood dictate. The fiber coupling while expensive avoids having to make the spectrographs mechanically stable enough to wiz about the sky... ... it can have a down side though in that I wasted one exposure last night with the wrong fiber connected sending the photons into thin air!

Regards Andrew 

PS If you have not seen it have a look at Francois Teyssier "Low Resolution Spectroscopy Observers Guide" available here http://www.astronomie-amateur.fr/ in English.

Edited by andrew s
PS added
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Very neat.  Makes my start with the SA100 and 9.25" SCT at f/6.3 look very humble.  Just shows with great ingenuity what is achievable from the backyard.  Looking forward to seeing the Hi-res results when available. Having read Ken Harrison's book I know what a challenge targeting the fibre/slit can be!

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12 minutes ago, Owmuchonomy said:

Makes my start with the SA100 and 9.25" SCT at f/6.3 look very humble.

I started there too Chris! What impressed me about The sky X is that it would still plate solve with all the slitless spectra in the field so I could make sure I was looking at the right stars spectra. 

Regards Andrew. 

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