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Rather than hijack Daniels thread I will respond to Bernard here.

I had used ISIS with the first version of my spectrograph which used an echelle with the same characteristics as the eShel. However, when I updated it for my new telescope to a larger echelle I saved money by getting an over stocked grating but it had a different blaze and lines/mm to teh eShel.

I tried to use ISIS and worked at it for a considerable time but I could not get past the camera rotation stage and the setting of the alpha and gamma angles and hence the assignment of the orders. See figures 22 to 26 here http://www.astrosurf.com/buil/isis/eshel/tuto1.htm

I assume this was because ISIS used a model based on the spectrograph characteristics. However, I could not prove this.

In the end I decided to use IRAF and got that working with help of this forum.

Regards Andrew

Hi Andrew,

Your ISIS 'failure point' is where I assumed it would be. A couple of years
ago I tried to help Carl Sawicki use ISIS to reduce his SQUES (with Relco
cal line) ecelle spectra and that is where we also floundered. I recently
changed my eShel camera from an ST-8 (KAF-1603) to a QHY22 (ICX-694) and it
took a lot of fine tuning of the camera rotation angle and messing with the
alpha and gamma values before it all worked well. While I can't be 100%
confident I do feel that if we had persisted we could have got it to work
with ISIS, as I see no obvious reason why the programme could not handle it.

Cheers,
Bernard

-----Original Message-----
From: Andrew Smith
Sent: Monday, September 18, 2017 12:04 AM
To: fg-spek-admin@vdsastro.de
Subject: [fg spektroskopie] ISIS and my echelle

Link zum neuen Beitrag: http://forum.vdsastro.de/viewtopic.php?t=4918#p30258

Rather than hijack Daniels thread I will respond to Bernard here.

I had used ISIS with the first version of my spectrograph which used an
echelle with the same characteristics as the eShel. However, when I
updated it for my new telescope to a larger echelle I saved money by
getting an over stocked grating but it had a different blaze and
lines/mm to teh eShel.

I tried to use ISIS and worked at it for a considerable time but I
could not get past the camera rotation stage and the setting of the
alpha and gamma angles and hence the assignment of the orders. See
figures 22 to 26 here
http://www.astrosurf.com/buil/isis/eshel/tuto1.htm

I assume this was because ISIS used a model based on the spectrograph
characteristics. However, I could not prove this.

In the end I decided to use IRAF and got that working with help of this
forum.

Regards Andrew


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_________________
Quicquid Nitet Notandum

Hi Bernard, I did not easily give up on ISIS. I spent considerable time trying different rotations and angles in a systematic manner. However, I could not get close. I reasonably sure that it is because ISIS uses a model of the echelle based on the eShel grating to decide which calibration lines should be in which order and where. I conclude that this is not compatible with my grating. I also had used the RELCO lamp with success with my initial echelle.

I then under took the adventure of learning Linux and IRAF to the point where I can simply reduce my spectra so I am less motivated to revisit ISIS again for this. However, given the almost constant cloud we now seem to have I may try again. However, Daniels new software may take priority.

I am currently building another echelle of higher R and a design close to CB's VHIRES and so will use IRAF for this as well.

Thanks for your interest and help.

Regards Andrew

I have two echelle spectrograph, one is an eshel from Shelyak, the second is a prototype of Eshel+ (R about 30000).
For this two spectrographs, I use ISIS to reduce the data of course with different parameter and it work well.

But it's difficult to find the right parameters and also the right exposure time for the Th/Ar lamp.

Hi Olivier,

Thanks for the confirmation that ISIS can handle non-eShel instruments,
which is what I thought.

Cheers,
Bernard

-----Original Message-----
From: Olivier GARDE
Sent: Tuesday, September 19, 2017 9:36 AM
To: fg-spek-admin@vdsastro.de
Subject: [fg spektroskopie] Re: ISIS and my echelle

Link zum neuen Beitrag: http://forum.vdsastro.de/viewtopic.php?t=4918#p30268

I have two echelle spectrograph, one is an eshel from Shelyak, the
second is a prototype of Eshel+ (R about 30000).
For this two spectrographs, I use ISIS to reduce the data of course
with different parameter and it work well.

But it's difficult to find the right parameters and also the right
exposure time for the Th/Ar lamp.


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_________________
Quicquid Nitet Notandum

Oliver I know the Eshel+ is different to the eShel but do the gratings have the same lines/mm and blaze angle ?

If they are different then it would be worth me trying again.

Thanks Andrew

On further thinking about this I suspect it may have been the physical rotation of the camera that gave me the issues I had. Certainly ISIS has all the data needed to account for different gratings

At the time I was using an FLI Microline which has a square casing. In view of this I probably did not try hard enough to align the "four Th Ar lines" horizontal.

I now use a SX camera so it could be rotated so I will revisit ISIS.

Thanks for the stimulus.

Regards Andrew

From my own, and other's, experience the physical orientation (rotation) of
the camera is all important, and needs very fine tuning, to get everything
working. Despite published advice to set the 'four ThAr lines' horizontal I
had to set them a bit 'off' to achieve alignment.

Cheers,
Bernard




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Quicquid Nitet Notandum

I think this is my problem as the 4 lines are at the extrems of the of orders 34 and 35 with my grating see attached.

Andrew,

Using way off-centre lines may indeed be the main problem. As ISIS allows
you to define a different ref line, and set of rotation lines, I suggest you
select a good line near the centre.

Cheers,
Bernard

-----Original Message-----
From: Andrew Smith
Sent: Tuesday, September 19, 2017 11:03 PM
To: fg-spek-admin@vdsastro.de
Subject: [fg spektroskopie] Re: Re: ISIS and my echelle

Link zum neuen Beitrag: http://forum.vdsastro.de/viewtopic.php?t=4918#p30276

I think this is my problem as the 4 lines are at the extrems of the of
orders 34 and 35 with my grating see attached.


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Quicquid Nitet Notandum

Andrew,

Here's the difference between eshel and ESP gratings :

ESP :
52,4 grooves per mm
Alpha : 65 deg
Gamma : 4 deg

Eshel :
79 grooves per mm
Alpha 63.1 deg
Gamma : 5.75 deg

Thanks Olivier, your ESP grating is close to mine. Mine has a blaze of 63.5 deg and 52.67 l/mm. I got the orders wrong in my previous post as I was quoting my original version of MRes. The orders should have been 51 and 52 for the "Four Th" lines.

Looking at the data still in ISIS from my attempts I did use different reference lines but I found an error in the order assignment.

I will try again with ISIS with the correct order this time.

Thanks Andrew