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Frequently Asked Questions

* DATA REQUESTS

1. Why do I get 2 IUESIPS MELO files for some low dispersion images but only 1 NEWSIPS MXLO file?

2. Can I request IUE data in ASCII format?

3. Why are some IUE NEWSIPS data not available? The IUESIPS version is available from the archive.

* READING FILES

4. How do I read NEWSIPS files into IRAF?

5. How do I read NEWSIPS files into IDL?

6. Why are my RDAF-format iuesips files unreadable after I transferred them from NDADS to my unix workstation?

7. Can I use SAOimage to look at NEWSIPS files?

* NEWSIPS PROCESSING

8. What is the wavelength scale used for NEWSIPS? Is it heliocentric?

9. I have a NEWSIPS image which may not have been processed correctly (wrong dispersion, wrong exposure time). How can I get a correct version?

10. Why are there differences in IUESIPS and NEWSIPS wavelengths?

11. The wavelengths for my high-resolution NEWSIPS spectra seem to be off by almost an Ångstrom. What happened?

* ASCII LOGS

12. Are there ASCII files of the IUE Merged log?

* DATA ANALYSIS

13. When analyzing data, which of the data quality flags should I use to throw out pixels?

14. When coadding like spectra, should I weight the constituent spectra by exposure time or the square root of exposure time?

15. Whew! Is there a simpler way of estimating noise?

16. Why do I see emission lines in NEWSIPS LO data that seem too low?


1. Why do I get 2 IUESIPS MELO files for some low dispersion images but only 1 NEWSIPS MXLO file?

2. Can I request IUE data in ASCII format?

3. Why are some IUE NEWSIPS data not available? The IUESIPS version is available from the archive.

4. How do I read NEWSIPS files into IRAF?

5. How do I read NEWSIPS files into IDL?

6. Why are my RDAF-format IUESIPS files unreadable after I transferred them from NDADS to my unix workstation?

7. Can I use SAOimage to look at NEWSIPS files?

8. What is the wavelength scale used for NEWSIPS? Is it heliocentric?

9. I have a NEWSIPS image which may not have been processed correctly (wrong dispersion, wrong exposure time). How can I get a correct version?

10. The wavelengths for the Mg II h and k lines are very different, by almost an Ångstrom, between my IUESIPS and NEWSIPS high-dispersion data. Is this an error?

11. The wavelengths for my high-resolution NEWSIPS spectra seem to be off by almost an Ånsgtrom. What happened?

12. Are there ASCII files containing the IUE Merged Log?

13. When analyzing data, which of the data quality flags should I use to throw out pixels?

14. When coadding like spectra, should I weight the constituent spectra by exposure time or the square root of exposure time?

15. Whew! Is there a simpler way of estimating noise?

16. Why do I see emission lines in NEWSIPS LO data that seem to be low

  • Cathy Imhoff's report indicates that this can occur if the source was miscentered on the slit and there is low background flux.