Close × 2022 March 19: The HLA footprint viewer no longer works because it relies on Flash. If you need footprints, we recommend using the MAST Portal. Note that the Portal also gives access to the new Hubble Advanced Products (HAP), which include more recent observations. The HLA contains no observations acquired after 2017 October 1.

Image of the Month for June 2010

Antennae Galaxy: Emission Line Spectra from Young Star Clusters

Highlighted HLA Features:

• Find and examine spectra.
• Use the line plotting tool to measure flux and wavelengths.
• Ability to determine the redshift and velocities with relative ease.

This display can be reproduced in the HLA by using the following steps. Clicking on the image above will go directly to the spectral line plotting tool for O5HE06010.

1. Type hla.stsci.edu into your browser. Click on the "Enter Site here" button.
2. Click on the "Advanced Search" link, which is to the right of the HLA Search Box.
3. Uncheck the All Instruments Selection.
4. Select STIS by checking its box, it's listed in the Standard Products section.
5. Type "antennae" into the empty search box and hit the "return/enter" key or click on the "Search" button.
6. Click the Images tab.
7. Scroll down and locate the NGC4038-142 STIS/CCD G750M 52X0.2 O5HE06010 image. It will be on the 2nd page. Click the Interactive display link.
8. With your mouse in the Interactive Display on the top horizontal line, (i.e. the continuum spectra), type "L" to invoke the Spectral Line Plotting Tool.
9. "Zoom in" on the Hα and NII lines (i.e., the three bright lines on the left) by drag selecting in the upper or lower region.
10. Click on "Enable Fitting" then select the min/max points on either side of the Hα spike (i.e, the tallest spectral emission feature) by clicking on both sides of the spike. The flux parameters will be calculated for your selected area.
11. Enter the Hα wavelength, 6564.6 (in vacuum), into the Rest Wave text box. The redshift and velocity will be calculated.
12. Smooth the spectra by using the Coadd (add several rows together) or Smooth (add several wavelength pixels together) features in the line plotting tool.

Additional Information:

• To see the aperture of this visit, one can select the visit in the images display, then click the Footprint tab. Use this link to see a screen capture of the footprint display with this visit selected in yellow.
• Similar steps can be taken for absorption lines, for example search for STIS visits on "Antennae" and select NGC4038-289 STIS/FUV-MAMA G140L 52X2 O5HE01020.
• For more information on the spectrum used for this example, see "Space Telescope Imaging Spectrograph Observations of Young Star Clusters in the Antennae Galaxies (NGC 4038/4039)" by Brad Whitmore, et al (i.e., visit 6 shown in Figure 1, 2B, 6B of the article).

Previous HLA Images of the Month

June 2010 Home Help Center Contact Us Acknowledgment STScI/ST-ECF/CADC