EUVE FAQ

1. Where do I get EUVE archival data?

• As of Nov 1997, the EUVE project in Berkeley is no longer delivering EUVE archival data. Events and image datasets, which may be reduced to create spectra and light-curves are available from this web site: click here to search the EUVE archive.

2. How do I get multiple EUVE datasets?

• If you are requesting multiple EUVE datasets, for now (since the data resides at HEASARC ) you have to click on each data set or go to their ftp site. We will have a batch option in the future.

3. What are the wavelength ranges of the EUVE instruments?

•  Spectrometer   Range (Ang)    Resolution  
      SW           70-190          0.5 Ang
      MW          140-380          1.0 Ang
      LW          280-760          2.0 Ang
       
   Imagers:       10% Filter Bandpasses (Ang)
   DS Lexan              67-178               
   DS Al/C              157-364      
   ScA/B Lexan           58-174               
   ScA/B Al/Ti/C        156-234      
   ScC Ti/Sb/Al         345-605      
   ScC Sn/SiO           500-740      
  
  

4. What are the common EUVE spectral features?

• The EUVE spectrometers have some common background features caused by airglow and scattering in the upper atmosphere.

  SW- The short-wavelength spectrometer can have a bright rim at shortest wavelengths (left) caused by scattered Lyman alpha.

  MW- The medium-wavelength spectrometer has a broad feature at 304 Angstroms from geocoronal helium.

  LW- The long-wavelength spectrometer has a broad feature at 584 Angstroms from geocoronal helium, which includes the 304 Angstrom line in second order.

5a. What about the Deep Survey Deadspot?

• There is a region of low gain (the "dead-spot") near the center of the Deep Survey Lexan/B band caused by the Feb 1993 observation of HZ 43. The region is about 2 arcmin in diameter and is described in detail in the EUVE technical memo.

5b. What about the Deep Survey's short wavelength response?

• The short wavelength response of the DS has been investigated to explain large count rates observed from high column sources, like Sco X-1 and has often been termed "X-ray leak". The latest ideas have been summarized in John Vallerga's Memo.

6. How do I get started with the EUVE permanent archive data?

• Once you have obtained events and/or fits images from http://archive.stsci.edu/euve/search.php

  3 steps to read them:

  1) gunzip the files.

  2) read fits files with strfits (in stsdas.fitsio) (step no longer needed with IRAF 2.11, which allows you to read the fits files with out converting them. And cep will run on fits files).

  3) the img file will produce ds,sw,mw,and lw images + good times tables [you can go onto spectral extraction from these or continue and reduce the events files.]

  4) the evt file will produce the equivalent of the old format data (like table0 and so on) tables produced will have the following names: adcnts.tab lw_events.tab orientation.tab sw_events.tab ds_events.tab mw_events.tab quadrant.tab valid_times.tab )

  5) run cep to produce qpoe files using the appropriate script in archpipe (in egodata1.16) {Note: Only use "Rebuild DS SourceCentered Archive QPOE" for moving targets}

  6) use qpoe file as before

  Please also see the Permanent Archive Guide EUVE Permanent Archive Data Products Guide

7. How do I extract an EUVE Spectrum?

• In IRAF Use the EUV task euvextract on the two dimensional image file (which you get get from the source_date_img.fits file). See also: quick help on Spectral extraction?

8. I run euvextract and get an error: "dispaxis not found".

• You are missing DISPAXIS header line. This card was omitted from the EUVE archival format because it is specific to reduction of spectra under IRAF and, unlike the old GO products, the archival data format is not IRAF-specific.

  You can add the DISPAXIS card to an image with the standard IRAF task hedit . It will need to have the value '1', meaning the spectra run along the x-axis, as long as you haven't rotated the images.

9. How do I make a Deep Survey Light-curve?

• Quick Help on making a DS Light-curve