First light for Alpy 600 at THO

[Robin Leadbeater]

first light for my new Alpy 600.

Alpy_first_light_sky.png (16.45 KiB) Viewed 11256 times

Not very exciting I am afraid, just sunlight filtered through the clouds. Wavelength calibration was done using Ne and Ar lines from a Relco fluorescent lamp starter.

More to come once we get some clear skies.

Cheers
Robin

[Christian Buil]

Robin,

Congratulations for Alpy!

A small note about focus. The preferred spectral region is between 3800 and 7300 A.
Alpy 600 is optically optimized for give a very uniform spectral quality inside this
domain. Should not try to focus particularly the infrared part (also affected by the
order recover). My recommendation is to focus the visible and UV part
and forget IR portion above 7500 A (not used).

Christian

[Robin Leadbeater]

Here are the results of the first star target (CH Cyg) for my new Alpy

chcyg_alpy_20130530_annot.png (32.89 KiB) Viewed 11191 times

The setup is Celestron C11 , reducer (giving ~f5) Alpy 600 and guiding modules, ATIK 314L+ imaging camera and DSI Pro guiding camera using PhD software. I also have a reversed flip mirror between the focal reducer and the guider, partly to fill the gap but it could also allow light from a calibration lamp to be injected.

The observing session went reasonably well given this is a new spectrograph. To get good resolution it is important to focus the spectrum well. This is very critical with a fast short focal length system like this and also fiddly because of the interaction between the orientation of the spectrum and focus. Also it cannot be done without removing the spectrograph from the telescope and partially dismantling it. Hopefully it will retain focus well over time. (I am also planning to add a rotateable camera mount so small rotation errors can be corrected without losing focus when changing the imaging camera between spectrographs)

One problem (which was new to me not having done much full spectrum slit spectroscopy before) was the large dynamic range in the flats (My normal Halogen lamp and diffuser in front of the telescope gives a very low signal at the violet/UV end) I finally removed the large lamp spectrum gradient from the flat using a spline fit and used this normalised flat to correct the spectra. (A flat is particularly useful with the Alpy as it shows significant waves in the instrument response which can be difficult to correct without flat correcting first.)

Cheers
Robin

[Francois Teyssier]

Looks very good Robin

Could you please send me the fit files
Margarita K. is interested by a survey if the star during this active stage
I'll open an aras page this week end in order to gather spectra
But now I'm on the boat from Marseille to Corsica
Bonne continuation
Francois

[Olivier Thizy]

Congratulation Robin, excellent results. Any pic of the setup?

Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/

[Robin Leadbeater]

Could you please send me the fit files
Francois

OK will do. Have a good trip

Here is a photo of the setup for Olivier. I was very lucky with the DSI Pro for the guider. It just reached focus with about 0.5mm to spare

Robin