About Miles data base

[Paolo Berardi]

Ken, you write while I answer this (I'm glad you solved):

I'm trying to use Marco&Poulo's spreadsheet for the Miles database...
I can't seem to be able to down load the test.dat files from their nominated site - and the other sites have the database in test.fits format...

Hi Ken, please try to download now from here:
http://quasar.teoth.it/html/varie/MILES_OBS.zip

This is the Excel spreadsheet related to database:
http://quasar.teoth.it/html/varie/SPEC_VIEW_V2.zip

Extract SPEC_VIEW_V2.zip in any place with folder structures option enabled.
SPEC_VIEW_V2 folder should contain:



Extract files s0001-s0985 (file extension .test.dat) from MILES_OBS.zip in the empty folder MILES_OBS. Open the spreadsheet (the version you can use).

Martin, NOAO spectra are very useful, thanks for link and spreadsheet. I wonder if also UVES spectra can be suitable for calibration purpose. They are R=80000 spectra so I think should be resampled and filtered with gaussian algorithm before using them. I see there are many in "Field star" section:

http://www.eso.org/sci/observing/tools/ ... tonow.html

It's a pity they have a "hole" around 5800 A, anyway could be interpolated during continuum extraction.

Ciao
Paolo

[Ken Harrison]

Paolo,
Thanks.
Now up and running!
(BTW The link to the Miles database in your last message seems to work directly! Good news.)

[Martin Dubs]

Hello Paolo,

I have used the UVES database occasionally, but I find it rather cumbersome to get the spectra in suitable form for ISIS: The way I do it is to:
- download the tfits merged spectrum archive
- extract the tfits file with 7-zip
- open the file with Fitsview (http://heasarc.gsfc.nasa.gov/docs/software/ftools/fv/)
- select the columns for wave and flux
- export the table with space delimiter as *.dat
- with ISIS: interpolate the gaps, smooth the spectra to the desired resolution and resample at 0.1 A, (VSpec seems to be overloaded by the size of the files)
- save the result in .fit or .dat format
Maybe there is a simpler way, but I used it only rarely for comparing with my echelle spectra.
Advantage: very good normalization, no ripples which are typical for echelle spectra.
I recently had the chance to visit Paranal, very impressive!

Regards, Martin

[Martin Dubs]

Hello,
a note of caution:
the above method works only for single downloaded orders or for the creation of *.dat files. Unfortunately the sampling interval of different wavelength ranges is different, which makes the correct spectrum extraction difficult:
from data description
http://www.eso.org/sci/observing/tools/ ... ml#column6

The tfits tables include a different binning for each instrumental setting.Unfortunately IRAF noao>onedspec>splot does not support multiple binning.In order to plot the merged spectra with splot, you must first transform the tfits tables into standard iraf spectra.

The same problem seems to occur with ISIS. A workaround is to download shorter spectra.

Regards,

Martin

[Paolo Berardi]

Very well Ken , thanks for feedback!

Martin, thank you for detailed extraction procedure.
So, UVES spectra are difficult to use entirely, what a pity!
Fortunately Miles and NOAO are very useful resources...

I recently had the chance to visit Paranal, very impressive!

Wow, congratulation for your great experience! ESO telescopes are "state of the art" technology but sky is not less!

Best,
Paolo

[Robin Leadbeater]

Hi Martin, Paolo

I dont normally download the full spectral range on UVES spectra as I am normally using it for LHIRES spectra over a limited range but I have managed to get the full range with Vspec. (It takes time to display the first time but if you immediately resample to something more manageable eg 0.1A it generally copes) This is the procedure I use.

From here
http://www.eso.org/sci/observing/tools/ ... tonow.html
select "Plot" for the star you want
select the range you want, select ascii file format and click plot.
save the txt file and change the file type from .txt to .uvs
Vspec can then read the file direct (chose .uvs from the drop down list of file types)
Note it takes about 20sec to load a full spectrum on my laptop
Once it is in Vspec you can resample or export it as dat if you like

Cheers
Robin

[Robin Leadbeater]

Note though that as I read it, because master response curves were used to reduce these spectra rather than standards measured on the night,
http://www.eso.org/sci/publications/mes ... vespop.pdf
the flux calibration of the UVES POP spectra may not be that good, a figure of 10% being mentioned here
http://www.eso.org/observing/dfo/qualit ... l#response

Cheers
Robin

[Robin Leadbeater]

I had a quick look for any overlap between UVES POP and Miles and found this star. (HD33256 F2v) The continuum is significantly different for the two sources

Robin

[Paolo Berardi]

Thank you Robin, you gave us an important information. The use of Miles profiles remain one of the best way to calibrate wide-range spectra. For shared observations I remember was recommended to use (all observers) the same, close to target, reference star (i.e. eta UMa for SN2011fe). Also using Pickles library spectra we can at least to uniform the results.

Generically speaking I thought there was some tolerance for spectral intensity calibration (after all you can still see wavelenght calibrated only profiles) but it is evident that amateur spectroscopy evolves...

Cheers,
Paolo