ISIS Response function - using any reference star

[Robin Leadbeater]

Does anyone know of a way to use any reference star spectrum with the Response function in ISIS, not just those in the supplied database?
(Ideally it would be useful if the user could add new stars or lists of stars to the database, for example the ELODIE 3.1 library
http://www.spectro-aras.com/forum/viewt ... f=8&t=1369 )


Thanks
Robin

[Robin Leadbeater]

So how do people produce an Instrument Response using ISIS if the reference star is not in the database? I am currently using a workround, temporarily replacing one of the spectra in the database with the one I want, changing its name to match the one in the database but this is crazy. I am probably being stupid but there must be a better way.

Robin

[Andrew Smith]

Hi Robin - Sorry I don't know. I need to reset up ISIS having had to have computer rebuilt. Have you tried adding the spectra using the naming convention used by ISIS for its standard spectra and seeing if it adds the new spectra?

Regards Andrew

[Peter Somogyi]

ISIS is not in front of me, but I doubt you can make it easily choseable without any severe GUI work and design consideration (where to place the combo boxes, etc...).

Otherwise you can already just do a copy-paste + divide result spectrum, as you need to do anyway at lots of other places in ISIS.

If I'd get the source I'd likely work on such tasks. (Would have others, much more severe wishes on my queue: per-exposure calibration, flat decomposing + shifting.)

[Peter Somogyi]

.. I have managed now to extend miles2.lst, however Elodie looks like really hardwired.

However if I'd touch that code allowing a general use-case for pioneers, I'd rather ungrey the "Reference spectrum:" edit box let to do any free copy/paste.

Human beings won't remember any HDxxx number anyway - I have an own text file containing the ref. star for each target... the best was to match the "star name" you typed in the "Object:" field already, or have a button to find the match by string matching...or some text history. Just think in use-cases. Forcing to chose from a large complex dialog for a number you've already filled in several times - it's is just a duplicate woe at processing time.

And for planning BEFORE observing - you already use many other tools.

The only meaning of that dialog I've seen was for determining the star type - then trying Pickles was a nice handy feature. But I guess it's not a core processing functionality.

- Peter

[Robin Leadbeater]

Thanks Peter, Andrew

At least it seems I have not missed anything obvious. Extending the miles2.lst is another interesting workround (For some reason, The ISIS database does not even include all the MILES stars. Also the continuum calibration for the Vega spectrum chosen from the ELODIE archive is known to be incorrect but at least than can be replaced easily)

I'd rather ungrey the "Reference spectrum:" edit box let to do any free copy/paste.

I think a good solution would be if this box could be used to open a browser to select any file, similar to the way the selection tool works on the "Profile" display for example. I was surprised when I found that it did not work that way

It could also be useful to have a keyword in the fits header for the reference star used, similar to the way the comparison stars used are included in photometry data submitted to AAVSO/BAAVSS for example.

ISIS is a nice program but I suppose this is an example of the disadvantages of using a program which is not open source.

Cheers
Robin

[Paolo Berardi]

Hi everybody,

So how do people produce an Instrument Response using ISIS if the reference star is not in the database?

Robin, I just copy the profile (i.e. from Elodie library) into the working folder. Then adjust the possibile lambda offset (using compare/shift functions) and do the division. It would very useful to integrate another library and use the standard "Response" function of ISIS. Sadly, I don't know how to do it.

For some reason, The ISIS database does not even include all the MILES stars

It has been chosen a magnitude threshold. ISIS database includes stars brighter than V mag 7 (the fainter star has V mag 6.99). The only exception is a dozen of "strange" stars with mag < 7 that are considered inappropriate for the purpose.

Paolo

[Robin Leadbeater]

Hi Paolo,

With the ALPY "200" all the MILES stars are very bright so I can use any of them. A mag 8 star saturates in just 15 sec

Cheers
Robin

[Paolo Berardi]

Sure!

Sometime I use DAT profiles of fainter Miles stars or Elodie 3.1 stars using the related Excel spreadsheet (we speak about them in the forum). But I realize that it would be better to include all the library profiles in the very nice ISIS database page.

Paolo

[Robin Leadbeater]

Sure!

Well almost . With the ALPY 200 at mag 8 I normally just use 10 sec exposures. For example here is HD86986 at air mass ~1.5 showing a max ADU/pixel of 22k.

mag8_10s_ALPY200_22kADU.png (229.63 KiB) Viewed 8007 times

This is with the ATK314 2x binned though to minimise read noise on the faint targets. 10s is enough at mag 8 to give SNR ~100. Only at R~130 though !

Robin