Prsentation PowerPoint

1
Stage Spectro Observatoire Haute-Provence 21-24
Aout 2007
2
Installation Tests

• Library
• Elements
• Spectral Type
• Gnuplot
• Spectrum

3
Vspec preferences...

• Configure Vspec
• Menu Preferences
• Working directory
• Image file preferred format (fits or pic)
• Header coment
• Continuum zone
• Atmospheric lines file
• Reference preset of 2 calibration line
• Spectrum directory where is Spectrum.exe
• Language...
• Position of observation site, used only for the
  atmospheric extinction correction

4
Play with the image...

• Pixel informations
• Coordinates xy
• Pixel intensity I
• Thresholds adjustment
• Enter the value in the text box
• Play with the mouse right click cursor as the
  right button in maintained
• Move up or down increase or decrease the high
  threshold
• Move right, left increase of decrease the low
  threshold
• Reset come back to the thresholds registered in
  the image header with the "originanl thresholds"
  button

Ouvrir fichier image
5
Binning

• As simple as "a click"
• If only one spectrum in the image, correctly
  aligned click on the "Object binning" button
• Profile informations
• Move the cursor along the profile
• Xl position x of the pixel, wavelength (once
  calibrated)
• Intensiy I
• Sampling in Angström by pixel, profile always
  resampled to linear calibration (A/pixel) (once
  calibrated)
• Prepare the calibration
• Load the image of the lamp for reference
• Do "reference binning"
• The lamp profile is added in the same document,
  it contains 2 series intensity and ref1

6
Series...

• Document .spc
• ASCII File readable with notepad, excel,
  word...
• Definded by A.Klotz in 89
• A header followed by 7 columns
• Only columns 3, 4, 5, 6 are series
• Columns 1 and 2 are the abcisses (pixel and
  angstrom once calibrated) and the column 7 was
  used to invalidated pixels
• A document .spc can record 4 colums in a profil,
  sharing the same abcisses (calibration)
• Play with the series...
• Select the "active" serie by clicking on it with
  the mouse or through the drop-down listbox,
  change its color...

7
Calibration "2 lines"...

• With the neon...
• Select the serie Ref1
• Enter in mode "calibration with 2 lines"
• If the neon lines are unknown display the lines
  list with "display elements"
• H-alpha 6562.852 -gt neon lines are on each side
  -gt 6532.882 et 6598.953
• Select the line, enter the value or click on the
  line in the list
• Same for the second
• To validate the entry, do "Enter" or double-click
  in the textbox
• Calibration done, sampling updated...

8
Is it enought ?

• Display the atmopheric spectrum
• Ask for the H2O correction
• If atmospheric lines does not perfectly
  superimposed to the one of the calibrated profile
• Non-linear calibration required

9
Atmopshere spectrum

• Superposition of atmospheric line
• In list element, select the source file "atmos"
• "export" button

10
Characteristic atmospheric lines 6500-6600 Ang
11
Calibration with multiple lines...

• Calibration multi-line to improve accuracy
• Multi-line calibration button
• Select a line
• Find its wavelength in the element list
• Look at line intensity, click on a line and look
  at the cursor position on the profile
• Validate with "Enter"
• Eventually, re-click in the textbox before
  validating
• Barycenter is computed and the first line is
  added in the calibration line list
• Take as many lines as you can, well spread

12
Atmospheric lines identified...
1
2
3
4
5
13
Multi-line calibration...

• Calibration parameters
• Pick the polynome degree
• Regression equation coefficient are not yet
  computed
• The line list can be saved in a .lst file
• Click on "compute"
• If there is no inflexion point, the equation
  coefficient are computed
• Residus are also computed, the smaller they are,
  the better it is...
• Save the equation coefficient in a .exc file for
  later re-use
• Profile is calibrated
• A re-sampling linear is performed with an average
  sampling factor

14
Vérification avec le spectre théorique
atmosphérique

• Go back to the H2O correction
• This time, lines are correctly aligned all along
  the profile

15
Atmospheric lines elimination

• Spectrum adjustment
• Smoothing factor (link to the spectro)
• Intensity (linked to spectro and to quantity of
  water vapor in the atmophere at the moment of the
  observation)
• Display the result by looking at the division
• Adjust sigma the same for a given spectrograph,
  modify the width of the line
• Interactive adjsutment of intensity
• Image A intensity too low
• Image B intensity too high
• Image C correct

A
B
C
16
Save the result

• Save the corrected profile
• Corrected profile is the serie "Division"
• Temporary serie -gt if you save as is, the serie
  will be recorded...
• Move the serie as a fix serie, like "intensity"
• Serie fixes Intensity, Ref1, Ref2, Norm
• Save the profile under another name
• Comparaison Before-After
• We can always do better, try...

17
Calibration of another spectrum

• Star Delta Sco - Be
• Do the binning
• Calibration with multi-line
• Charge the equation from Altaïr
• Sync with only one line
• Put the polynome constant at zero
• Pick one of the atmospheric line and enter its
  wavelength
• Click on Apply in the equation frame
• The new constant is computed from the reference
  line
• Close...
• H20 correction
• Chack the calibration is correct superimpose the
  atmospheric spectrum
• Adjust parameters and look at "see the division
  result"
• Click on OK when adjustment is correct
• Move the division serie to the intesity serie
• Save, that's it...

18
Flux correction

• Altaïr, reference star...
• Because we have a "corrected" spectral in
  relative intensity
• Not too many lines, A type
• Scale continuum to 1
• Database of "corrected spectrum"
• UVES, from l'ESO
• Pickles (5Ang/pixel) in Vspec not suitable for
  sampling lt0.5
• Divide the raw spectrum by the "corrected"
  spectrum from library/database
• I raw I rep I corr
• I rep I raw / I corr
• Result green serie, to be smoothed...

19
Response curve

• Extract the continuum
• Menu radiometrie, "extract the continuum"
• Select the zone wich contains lines
• Right click "Remove"
• Once all zones cleared, button "Run"
• Filter coefficient dialog box adjust the cursor
  to match the continuum trend
• Close the smoothing dialog box
• Save the new serie as the THE instrumental
  response of your instrument, over this spectral
  range

20
Response correction...

• For a star ...
• Load the response profile and the star profile
• Do a division
• That's it...

21
Assitants...

• Two assistants
• From menu Assistant
• 0b_to_1c
• From image to calibrated and corrected from
  response profile
• Processing needed for BeSS
• 1b_to_2b
• From calibrated profile to profile corrected from
  the instrumental response, atmospheric lines and
  continuum removed

0b_to_1c from image to corrected profile
1b_to_2b additional corrections
22
Assistant images to profile calibrated and
corrected

• With images and instrumental response profile
• Not specific to LHIRES
• Neon or lamp lines shall correspond to the line
  list

23
Assistant corrections

• Link the corrections
• Instrumental Response
• Atmospheric lines
• Division by the continuum
• Each correction can be disabled
• Required files
• Instrumental Response profile .spc
• Object profile with extension "_1b"
• Interactivity...
• Atmospheric lines
• As for the correction stand-alone function,
  adjust the width and depth of the theoretical
  atmospheric spectrum
• Continuum
• As for the "divide by continuum" stand-alone
  function, remove the area where lines are and
  adjust the smoothing coefficient (spline)

24
Spectral line database

• Version courte du CRC Handbook of Chemistry
  Physics - Only element up to Iron are included
• VI/16 Line Spectra of the Elements (Reader
  1980-1981)Reader J. Corliss Ch.H.lt61st ed.,
  CRC Handbook of Chemistry Physics (1980--81)gt
• Catalog of spectral lines in star spectrum
• VI/71A Revised version of the ILLSS Catalogue
  (Coluzzi 1993-1999)COLUZZI R 1993ltBull. Inf.
  CDS 43, 7gt

25
Spectral Type

• Search the spectral type of a star
• Using SIMBAD... if internet connection
• With Vspec, using the Bright Star catalog
  included

26
Spectrum library
Gam Cas, type B0IVclose to B0V
27
Some calculations...

• On the H-alpha line
• Signal to noise ratio
• Select a region of the profile with no line
• Ration Mean/Standard deviation
• Standard deviation Square root of the sum of
  the differences suare between the intensity and
  the mean
• Mid-Heigth line width, equivalent width
• Diaolog box of measurement preferences
• To select the calculation to perform menu
  spectrometry, "measures preferences..."
• Or to simply compute the already selected values
  button "computations"
• Display results in infos window
• Line center, on a reduced zone
• Switch the profile display to "point mode" to
  accuratly see which points will be included
• Select "line center" in the "measures
  preferences"
• For each zone, re-compute using the button
  "computation"
• In the infos windows, can display header data and
  save the result file "infos.txt" in the Vspec
  directory

28
Reference the relative intensities...

• Intensities...
• Depends of the quantity of photons captured
• Depends on spectro efficiency, on guiding, on
  exposure duration, magnitude, spectral type...
• Are not "absolute"
• Which means only function of the magnitude and
  the spectral type
• Values with no reference, hard to compare with
  other spectra
• The continuum as reference
• Zone with no lines
• Defined in the preferences
• Or select "on the spot" with the mouse before
  scaling
• "Normalisation" or "scaling" or "take a
  reference"
• Defined as intensity"1" the mean of the
  continuum zone taken as reference.
• Divide all profile intensities by this mean
• Serie "Normalized" as the serie where the
  intesities are relative to 1 on the pre-defined
  continuum zone, pink serie

29
Equivalent Width

• Line in emission or absorbtion
• Reference to "1" the close-by continuum
• Measures preferences check box LEQ
• Toolbar "computation" button
• Results...
• In the wsndow "infos"
• Exportable as fichier .txt
• Link...
• Open all the profiles
• For each
• Select the line
• Compute the LEQ (EW in french)
• Export the infos
• Open with your preferred grapher
• Fields delimited by "tabulation"

30
Scripts...

• You like the consoles and the command lines...
• Go to mode console !
• Allows you to pass hard values for parameters
  instead of mouse selection
• You like the scripts...
• Link the commands in a text file
• Follow the syntax of each command
• Change the extension of the text file to .pgm
• Can include up to 3 parameters
• Type Run and the name of the script file
• File name with no .pgm extension
• Result in infos window...
• Not everything is scriptable...
• Many correction or processing requires user
  interactivity, not everything can be automatic
• Look at the assistant for the basic processings

31
BeSS format conversion

• Export in fits format - BeSS
• Add keywords BeSS to FITS standard keywords
• Can check if object name is recognized by Simbad
• BeSS instrument and observatory can be picked
  from a list
• List is an ascii test file named list_instru.txt,
  list_obs.txt which shall be in the Vspec
  directory
• BeSS additional default informations in
  preferences
• BeSS(2) to fill the BSS_COSM, BSS_TELL and
  BSS_CONT keywords with method description
• Can keep the default setting of Vspec or
  customized yours

32
Fits 1D file - BeSS format
Fits keywords concatenation

• Open fits 1D profile
• Same open box than spc profile
• In the drop-down list, pick "fit" instead of spc
• If click on fits 2D file a warning message is
  displayed
• Fits header
• To see the full FITS header
• Click on the brown line between white graphic
  zone and window title
• Right click with the mouse for the pop-up menu,
  pick Header display

33
Graphical exportation with Gnuplot...

• Executable Gnuplot
• Executable .exe
• Command file "gnu.bat" used by Vspec
• Scritp file written by Vspec "gnup.txt"
• Scripts used by gnuplot to format the plot,
  editable, used by Vspec "std.gnu"
• Other style file can be created and picked from
  the dialog box in Vspec
• Customize the plot with a Vspec dialog box
• Title, Scale, output file format (depends on the
  style file used .gnu)
• Vspec automatically generate a .dat file of the
  active serie if this file does not exist to pass
  it to gnuplot

34
Graphique Gnuplot

• Graph gnuplot
• Depends on the stype file
• With std.gnu, displayed on the screen
• If click on OK, exit from gnuplot
• And a .png file is written on disk

35
Gnuplot style file
Fichier style "std.gnu" Visual Spec propose un
fichier de script par défaut "std.gnu" il
génére à la fois le graphique à l'écran et un
fichier gif. Le fichier .gif est enregistré dans
le même répertoire que le fichier
profil.
Script de trace GnuPlot des profils
spectro de Visual Spec
Paramtre 1 nom du
fichier Paramtre 2 intitul du titre
Paramtre 3 valeur min en Y Paramtre 4
valeur max en Y Paramtre 5 valeur min en X
Paramtre 6 valeur max en X Paramtre 7
valeur ticks en X Paramètre 8 nom du fichier
png Exemples call "std.gnu"
"140699.dat" "88Her" 6500 7000 .2 1.8 call
"std.gnu" "140699.dat" "88her"
(echelle automatique)
set terminal windows
"Arial" 9 -gt doit afficher le graphique sur
l'écran set xlabel "" -gt défini les étiquettes
x, ici aucune set ylabel "" -gt défini les
étiquettes x, ici aucune set yrange 23 -gt
défini les bornes de l'axe Y set xtics 6 -gt
défini l'espacement entre les graduations en
X set xrange 45 zone libre -gt défini
les bornes de l'axe X set tmargin 2 -gt défini
les marges autour du graphique set grid -gt
affiche une grille d'arrière-plan set title '1'
,-0.5 -gt affiche le titre du graphique plot "0"
notitle with lines -gt trace le graphique à
partir du fichier et maintenant le fichier set
terminal gif small size 640,480 -gt doit afficher
le graphique dans un format gif set output '7'
-gt sauve le graphique dans le fichier set xlabel
"" set ylabel "" set yrange 23 set xtics
6 set xrange 45 zone libre set tmargin
2 set grid set title '1' ,-0.5 plot "0" notitle
with lines

• "style" file std.gnu in Vspec
• Can be customized...
• Refer to gnuplot website for command syntax and
  list

36
Spectrum...

• Synthesis of a star spectrum using an atmophere
  model
• From R.O.Gray
• Other simulation software exist
• A lot of astrophysical hypothesis underlying...
  Shall be used carefully
• Can be used to generated very high resolution
  spectrum, to better indentify the lines
• But, what a sport !
• You'll discover that many lines are blended...

37
Star atmosphere models...

• Atmosphere models
• By Kurucz
• File name coding
• Xxx temp eff
• Yy log(g)10
• Kx microturbulence
• Pxx metallicity M/H referenced to the Sun
• Example 82045k4p00
• 8200K T Eff
• 4.5 log(g) gravity log(g)4.5cm/s²
• k4 is the microturbulence speed, 4km/s
• p00 is the ratio metallicity M/H equal to 0.0
  for the Sun abundance or m05 for M/H-0.5 for
  0.32 time the sun abudance or p05 for M/H0.5
  for 3.2 time the sun abundance
• Correspondance table between spectral type and
  atmosphere parameters
• For indicative use... Each star has its history,
  the one we are looking for...

38
Simulation Altaïr spectrum

• Get its spectral type
• With the bright Star catalog (excel file in vspec
  directory, provided)
• Menu tools, item "Spectral type"
• Using the table...
• A7V would corresponds to a model
• T Eff 8000K
• Log(g) 4.5cm/s2
• If by default we pick k0 and p00
• 80045k0p00
• Not all the models are working...
• Erreur spectrum 1, excuting under DOS, we could
  see the reason of spectrum abort
• Generate the spectrum
• With the diaolog box interface Visual Spec
• Select the model, the wavelength range, and the
  sampling
• Enter the outpu file name, With the .dat
  extension !

39
Simulation Altaïr spectrum

• Spectrum.exe
• Run in DOS, with a command file
• Command file B.bat, written by Vspec with a batch
  file for Spectrum "b.rsp" in the spectrum
  directory
• If computation are going well, the wavelength and
  intensities are displayed in the DOS window
• Vspec automatically display the theoretical
  spectrum
• With cut and paste, the 2 profiles can be
  superimposed
• Normalize to "1" on the same continuum zone
• The interpretation is another story...