Website User Information

User guide to website

• View Star Table - View sortable table of all star records in the database
  • View Star Data - View full record for an individual star
• View Line Table - View sortable table of all atomic and diatomic lines as well as known DIBs with their properties
• View Equivalent Width Table - Select set of stars and lines to view measured equivalent widths
• Plot Spectra - Final reduced and summed spectra can be plotted, with many adjustable parameters
• Plot Nightly Sums - Plot reduced spectra of individual nights as well as total sums to investigate transient effects
• Star Population Correlation Tools - Perform correlations between various parameters and measurements across the population of stars in the database
• Correlate Equivalent Widths - Plot equivalent widths of all lines in one star against another star

View Star Table

This page displays a table of information about the stars in the database.

• The table, as it is displayed, can be downloaded as either a tab-delimited (.txt) or comma separated (.csv) file with the links at the top of the page.
• The column headers are all links to see the table sorted by that column.
• In the Spectograph column, "ARCES" refers to data taken with the echelle spectrograph at Apache Point Observatory only with the pre-8/2012 grating. "ARCES*" has data taken with the post-8/2012 grating. "ARCES**" has co-adding of data taken with both gratings.
• The d(pc) column shows the approximate distance of the star, in parsecs, and the unlabeled column next to it shows a code (explained below) for the source of the information.
• The v sin i column shows the measured rotational velocity broadening of spectral lines. The unlabeled column next to it shows a code (explained below) for the source of the rotational velocity information.
• The Std column shows 1 if the star is used as a spectral standard for comparing more reddened stars to for DIB identification and measurement. If the star was not used as a standard, the column shows 0.
• The FUSE and Cop columns show a 1 if the star was observed by FUSE and Copernicus, respectively.
• The f column shows the fraction of hydrogen in molecular form along the line of sight. The Lim column next to it is a flag variable which is set to 1 if the f value is an upper limit as opposed to a measurement.
• The Data link in the rightmost column goes to a page with the full information in the star record, including column densities, extinction parameters, and information about the spectra in our database

View Star Data

This page, linked to from the star table, displays the complete available information about a star.

• The top section of the page (Stellar Data) gives the star's properties (i.e. name, sky coordinates, brightness, spectral type, etc.)
• The sources for the observational data (V, B-V, Spectral Type) are given as a code. The meaning of the codes is listed here:
  1. Bright Star Catalogue or its Supplement (BSC)
  2. Hipparcos Input Catalog (HIC)
  3. Data are available in HIC, but another source (e.g. SIMBAD or literature) was used instead
  4. No data in BSC or HIC, so some other source (e.g. SIMBAD or literature) was used
  • Note: For RR Lyr variables, the photometry listed refers to the phase of maximum brightness, if a light curve was found.
  • Note: In the Comments column, references to the literature are generally provided only in cases where finding some or all of the stellar data proved particularly difficult, or where one or more of several references available were especially useful.
• "v sin i" shows the measured rotational velocity broadening of spectral lines. The Reference Code gives the source of the information:
  1. Abt, Levato, & Grosso 2002, ApJ, 573, 359
  2. Standard stars from GG2005*
  3. Simbad (but only if after 1982, usually)
  4. General catalogue of GG2005* (but only if after 1982, usually)
  5. Specifically UF(1982) from GG2005*
  6. Bright Star Catalogue (1982) or its Supplement (1983)
  7. Other
  • * GG2005 = Glebocki & Gnacinski 2005, ESA, SP-560, 571 = spectroscopic catalogue III/244 in online CDS collection
• The code next to the listed distance gives the source of the information:
  1. Hipparcos parallax of 4-sigma precision or better
  2. Spectroscopic distance modulus, Vo-Mv
  3. Member of an OB association, cluster, or multiple-star system
  4. Other
  • Note: In case 2, a ratio Rv = 3.1 and Blaauw's 1963 calibration of Mv in terms of SpT were used.
• The "Observing Data" section gives information about the observations of the star that led to the spectrum in the database.
• The "Extinction Parameters" section gives parameters for Fitzpatrick & Massa's derived extinction curves, both the 6-parameter and 7-parameter models. Derived UV Extinctions for both curves are displayed as well.
• The Exposure information shows the nightly sum spectra that are in the database and were used to make the final summed spectrum for the star.

View Line Table

This page displays information about the atomic, diatomic, and DIB absorption lines that may be found in the spectra.

• As in the star table, the data in this table is sortable by each column by clicking on the column header.
• The wavelength column shows the central wavelength for the line. For DIBs, which have small shifts in different stars, a weighted average is shown.
• The 'Vibronic Band' and 'Assignment' columns show the quantum mechanical designation for the transition for the molecular absorption line.
• The 'Obs?' column shows a 1 if the line has been observed in a spectrum in our database and a 0 if it has not been observed.
• The 'FWHM' column shows a weighted average full width at half maximum for the line across the stars in the database.
• The 'Strength' column shows the strength for each atomic line. The reference for these values is Morton, D. C. 2003, ApJS, 149, 205.
• The 'Comment' column includes a code describing the continuum surrounding the DIB line listed. The meaning of the letters is as follows:
  • i: isolated, no other absorption line close by
  • a: adjacent, another line is nearby and wings of absorption may overlap
  • b: blended, another line is within the core absorption of the line and separating is likely to compromised
  • e: enclosed, the line is enclosed within a much broader DIB
  • Note: multiple a's and b's refer to multiple adjacent and/or blended lines

View Equivalent Width Table

This page is an access point to all equivalent width measurements. Custom table are created to show equivalent widths, parameters, and column densities for the stars in the database.

• The Pick lines menu allows the user to select which lines will have equivalent widths displayed in the table. The lines are ordered by wavelength, and any number can be selected, by holding down "Ctrl" (on a PC) or "command" (on a Mac). In addition, by clicking the "Show All Lines" option at the top, all lines will be displayed in the table without need for menu selection.
• The Pick stars menu works similarly to the pick lines menu. The stars are listed in order of Right Ascension.
• The Pick parameters and Pick species menus will display the selected options alongside the line equivalent widths in the table.
• The default table has a row for each line and the stars selected across the columns. Clicking the option just below the menus allows the table to be flipped, so that each star has a row and the lines are in columns. This is useful if you are looking at a small number of lines across a large population of stars.
• Once the table is displayed, it can be downloaded as either a tab-delimited (.txt) or comma-separated (.csv) file using the links at the top of the page.

Plot Spectra

This page allows the user to plot the spectra in the database, with various tools to aid spectrum analysis.

• The table of stars to select from is sortable by any of the columns by clicking the column name. The default sorting is by Right Ascension, and can be seen by clicking the link at the top of the page. Stars can be added and removed after plotting as well.
• The plot generated can be downloaded as a .png image file by right-clicking on the plot.
• The axis ranges can be adjusted by manually entering values in the "Redraw with plotting range" boxes. The x-range can be shifted up or down by the size of the window by clicking on the "Move wavelength window" buttons.
• Any change in axis range or extra features to include in the plot will be applied after clicking the "Redraw" button (either one) or one of the "Move wavelength window" buttons.
• The default y-axis value is 1.0, and the offset is measured with increasing values farther down the plot. So an offset of -0.1 is at y=1.1, an offset of 0.4 is at y=0.6, and so on.
• Marks for known DIBs and atomic and molecular lines have a default offset of 0.3 (if nothing is entered), and echelle order center marks have a default offset of -0.1.
• The spectra are automatically velocity shifted to the rest frame of the interstellar gas (measured by the strongest potassium absorption line). Any arbitrary velocity shift can be applied by the user input.
• The spectra plotted can be downloaded (without the user-applied offsets and velocity shifts) by clicking on the link in the rightmost column of the table. The spectra are formatted as tab-delimited (.txt) files with wavelengths in the left column and fluxes (in arbitrary units with the continuum flattened to be at 1.0) in the right column.

Plot Nightly Sums

This page allows the user to plot the spectra in the database, including from individual nights of observing.

• The star selection menu is the same as for the regular plot function
• After selecting stars, users are given selection menus for each star to choose whether to plot the total sum spectrum or some set of individual nights.
• If the "Co-add nightly sums" box is checked, then the selection of nightly sums selected for that star will be added together to make one spectrum, rather than be plotted separately.
• If you want to plot a custom co-add alongside the total sum or individual nights, you can get an additional spectrum selection menu for the star by checking the "Duplicate" box and clicking "Refresh Star List."
• More stars can also be added at this stage from the star selection table at the bottom of the page.
• The options on the plot output page are largely the same as for the regular plot function
• In the table of spectra shown, the link in the rightmost column is to download the spectrum as a tab-delimited (.txt) file. The left column is wavelength in Angstroms, and the right column is flux in arbitrary units (flattened to have continuum level at 1.0). For custom co-adds, this is the only path to downloading that data, since the co-addition is done on command and is not stored for posterity.

Star Population Correlation Tools

This page allows the user to plot two variables across the population of stars against each other.

• Both the X and Y axis variables can be set to be an inverse or ratio by using the appropriate "Numerator" and "Denominator" boxes.
• Within each of the four boxes, select whether you are plotting measured equivalent widths, calculated column densities, or other parameters of the stars. "Unity" will set that variable to 1 for all stars. The drop-down menus for each option will show the full range of choices.
• By checking the boxes in the "Axis option" row, you can set either the Y-axis, the X-axis, or both to be on a log scale. The default is linear scale.
• The "Range" boxes will restrict the plot to show data in certain axes ranges, but do not restrict the data used for correlation calculations.
• The default beft-fit line is calculated analytically. To use Monte Carlo sampling (which crudely assumes Gaussian errors on equivalent widths) to calculate the best-fit line, check the appropriate box.
• On the resulting page with the plot, the table of data can be sorted by using the drop-down menu of columns and clicking "Redraw".
• Any stars can be excluded from the plot and calculations by unchecking the "Include?" box in the table.
• The residuals of the shown best fit correlation line are shown in the table, and can be plotted against other variables by clicking the link below the data table.
• The data table can be downloaded for further analysis as a tab-delimited (.txt) or comma-separated (.csv) file with the links at the bottom of the page.

Correlate Equivalent Widths

This page allows the user to plot equivalent widths of all lines in one star versus another star.

• In each menu, the star list can be sorted by HD or Star Name by clicking the column header.
• By checking the 'only plot DIBs' box, atomic and molecular lines will not be included on the plot.
• The default beft-fit line is calculated analytically. To use Monte Carlo sampling (which crudely assumes Gaussian errors on equivalent widths) to calculate the best-fit line, check the appropriate box.
• On the resulting page with the plot, the table of data can be sorted by using the drop-down menu of columns and clicking "Redraw".
• Any stars can be excluded from the plot and calculations by checking the "Exclude?" box in the table.
• The residuals of the shown best fit correlation line are shown in the table.

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