BEFS Search Output Columns

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This document defines the catalog entries describing the BEFS Data Archive as delivered to STScI by the Space Astrophysics Group of the University of California at Berkeley. Most of the documentation below was obtained from Van Dixon and other staff members of the Berkeley Extreme and Far-UV Spectrometer project.

Archive Background:

The Berkeley Extreme and Far-UV Spectrometer (BEFS), flew on the Orbiting and Retrievable Far and Extreme Ultraviolet Spectrograph (ORFEUS)-SPAS for 5 days in September 1993 and again for 14 days in November, 1996.

General Results Options

Most mission search results pages have the following general features/options. (Note that the sorting, paging and VOPlot options all require javascript to be turned on.):

1. Clicking on the column headings at the TOP of the results table will sort the returned results based on the selected field. Clicking the column heading a second time will sort the results in descending order. Note that a bug currently exists whereby exponents are ignored in numbers using exponential notation (e.g., 6.3E-3 is sorted as if it were 6.3). Since most tables don't include exponential numbers this is not felt to be a major problem.
2. Clicking one of the column headings at the END of the results table (or clicking the "columns help" link at the top of the page) will display help information about the search results page and the displayed columns (i.e., this page).
3. By default, results are shown with 50 entries per page, with links to additional pages if more than 50 entries were returned. The number of rows per page can be modified using the "Records per Page" form element on the search form. The total number of entries returned is set by the "Maximum Records" value from the search page. (Note that when the total number of returned rows is a multiple of 50, an extra page is displayed with no entries.)
4. One numerical column can be plotted versus another using VOPlot.
5. For some missions, thumbnail images of the reurned entries can be displayed by clicking the link listed just below the VOPlot link.
6. The mark column, as described below, can be used to plot spectra and download files.

Column Information

Mark

Mark this image for retrieval from MAST or to use the coplotting utility.

To Retrieve:
After selecting the desired files, choose the desired format for your download (.tar, .tar.gz, .tar.Z, .zip) and then click the "Download selected datasets" button to download the selected files.

To Coplot:
After selecting up to 15 observations to be plotted, click on the "Plot marked spectra" button to coplot the selected observations.

The spectra that you selected will be automatically scaled to the full range of wavelengths and nearly the full range of fluxes (i.e., y axis plot scale runs from 0 (or .25 * the minimum flux for spectra with negative fluxes) to the 10th highest flux). Each spectrum is automatically assigned a color, up to a maximum of 15. The spectra are labelled by their dataset names, with a summary of the datasets plotted given below the plot. After inspecting the plot, you may wish to change the selection of datasets which are displayed. Use your browser "Back" button to do this.

Plot range
Adjust the minimum and maximum wavelengths (in \305ngstroms) and minimum and maximum fluxes (in erg/cm2/sec/\3 05) to select the spectral region of interest and to exclude noisy data.

Plot dimensions
Adjust the X size and Y size in pixels to create the size of plot desired. The maximum dimensions are 850 by 64 0 pixels.

Redraw plot
Use this button to replot the spectra when you have changed the plot range or plot dimensions.

Target Name

The project-assigned name of the astronomical object. Clicking on the object name entries will display a preview spectrum.

Alt Object ID

The Simbad-derived name of the astronomical object.

Data ID

The 4-digit observation reference number, preceded by "BEFS", which uniquely identifies each BEFS observation.

Reference

The ref column specifies the number of published papers referencing the listed BEFS observation (data ID) A dash (i.e., "-") indicates that there are no known papers referencing the listed observation. Clicking on an entry in this column (i.e., an entry other than a "-"), will display the list of referenced papers including title, primary author, and journal citation. The journal references use the ADS Bibliography code, and are links to the ADS Abstract Service.

RA (J2000)

Object's Right Ascension in J2000 coordinates specified in hours, minutes, and seconds.

Dec (J2000)

Object's declination in J2000 coordinates specified in degrees, minutes, and seconds.

Obs Start Time

This is the GMT time of the start of the observation (Note, although stored in the database to the nearest second, the default print format truncates the date to the minute.) BEFS1 observations were obtained in September, 1993 and BEFS2 observations were obtained in November, 1996.

Exposure Time

The total exposure times in seconds.

Gratings

BEFS spectra were obtained using 4 gratings, simply designated as "a" (~380-510 Å), "b" (~510-690 Å), "c" (~700-900 Å) and "d" (~870-1175 Å). a and b were recorded by Detector 0, while c and d used Detector 1. Data from all 4 gratings could be obtained simultaneously, although short wavelength (Detector 0) data was obtained for only a small number of targets.

Mission Number

The mission number, either 1 or 2 (currently only BEFS-1 data ia available.

Object Category

These are broad categories assigned by the BEFS project. The possible categories include:

• Other
• Binaries
• White Dwarf
• Early Type Stars
• Planetary Nebulae
• Coronae/Late Stars
• Cataclysmic Variable
• Extragalactic Object

IUE Class

The IUE classification system originally used for categorizing IUE observations (provided by MAST).

Spectype

The MK spectral type of the observed object, as provided by Simbad.

Comments

Remarks about the observation.

Angular Separation

The angular separation in arcminutes between the observation and the search center (the coordinates you're searching on). This is calculated during the search, and the search results are sorted in order of increasing angular separation. It has the nice effect of sending parallels to the bottom of the list. (If you're interested in the parallels, you can sort the list in descending order of angular separation.)

It also means that you can give a search radius like, say, 2 .. 8 to find all observations between 2 and 8 arcminutes from some position. This could be used, for example, to exclude observations of the nucleus of a galaxy, or the central star in a planetary nebula.

Galactic Longitude

Galactic Longitude for the observation.

Galactic Latitude

Galactic Latitude for the observation.

Ecliptic Longitude

Ecliptic Longitude for the observation

Ecliptic Latitude

Ecliptic Latitude for the observation

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