2011-12-08

[Marco Leonardi]

Tonight I am observing gamma Cas. Very interesting B star.

Cheers,
Marco

[Thierry Garrel]

Hi Marco,
you have a very good osc index, much more better than me. Very good seeing or very good guiding ? What is your focal ?
Did you try to used Astro Art for autoguiding ?
I had before a MX916, very sensitive and easy camera, low noise, huge full-well capacity, fast, but if i remember well the pixel are big, about 23µm, and not exactly square. does it cause any problem to the data reduction ? Undersampling for example.
And finally, if your are not exhausted by my questions, what is your guiding cam ?
Great screen shot, thanks

[Marco Leonardi]

Hi Thierry,
thanks. This is my set up:

- C9.25 at F/10
- I use PHD guiding for autoguiding + EQMOD ASCOM for PEC control. The two softwares work simultaneously.
- My ccd to make spectra is SX-MX916 working in bin 1:1 so the pixel have the following dimension: 11.6 x 11.2 um
- To guide I use a guiding scope installed over the C9.25 (see picture). The mount is an EQ6Pro.
- The guide scope focal lenght is 480 mm and the diameter is 80 mm.
- The guide camera is an Orion SSAG.

The seeing condition was no so good because a light cloudy hide the star (not very clean visible with naked eye) + light pollution typical here in Milan suburb.

I can reach much better osc index (0.45 - 0.5) if I have a sky clear, stable and without clouds. EQMOD ASCOM is very important to support PHD on guiding quality. Also the counter weight installed in the Losmandy bar just at the top of scope help a lot.

Some picture here below.

à bientôt!

Marco

gamcas.jpg (4.56 KiB) Viewed 6715 times

[Thierry Garrel]

Thanks Marco for yours answer.
Now i know why my osc index is worse than yours. I'm guiding with 1500mm fl at prime focus and don't used PEC, cause i'm using an Altaz mount.
Clears Skies

[Olivier GARDE]

Hello Marco,

I noticed you guide with a refractor in parallel.
Why you don't use the exit guiding of the LHIRES ? (to see the slit and the star) and how you check that the star is actually in the slit especially with faint stars ?

Finally, the difference of focal length between the guide scope and the main telescope is perhaps a little too important (480mm vs 2280mm).

Have you try to guide with your main scope ?

[Marco Leonardi]

Hi Olivier,
thanks for your comment. I have not a LHIRES but a Spectra L200. This spectroscope has not a reflective slit. So I use a virtual reticule (Al's Reticule = http://www.iceinspace.com.au/forum/show ... hp?t=58485). LHIRES reflective slit is better of course. In the past I tested different type of modified flip mirror to use the main scope but finally my results was no so good as aspected. So at the moment I prefer to use a guide scope that permit me to guide also on faint targets with the virtual reticule. With the modified flip mirror is difficult to guide on faint target and also to have enough light to make a spectra. Finally I prefer to have the spectroscope connected directly to the main scope to avoid flexures.
CIAO !
Marco

[Olivier GARDE]

Hi again Marco,

Hop, I'm sorry but I do a mistake when I saw the picture of your set up, I was convinced it was a LHIRES and I understand better now why you are using is set up.

[Thierry Garrel]

Yes, it would be a good idea to present the L200 somewhere in the forum, cause it is a very insteresting and versatile spectroscope and it remains a little bit mysterious to us

So Marco...
Tchao