Spitzer Heritage Archive: Overview

The Spitzer Heritage Archive (SHA) is the final repository for all of the data collected by Spitzer. It is also the mechanism by which current users of Warm Spitzer download their data.

Note that there are also SHA video tutorials, including a quick start and a longer AAS-demo-style overview, available at the IRSA YouTube channel. Look for the playlist that combines all the SHA videos together.

The Spacecraft and Instruments

The Spitzer Space Telescope (formerly SIRTF, the Space Infrared Telescope Facility), was launched into an Earth-trailing orbit on 25 August 2003. Consisting of a 0.85-meter telescope and three science instruments, at the time of its launch, Spitzer was the largest infrared telescope ever launched into space. The instruments aboard Spitzer (IRAC, IRS and MIPS) obtained images and spectra at wavelengths between 3 and 180 microns, with spatial resolution ranging from 2 arcseconds at the shortest wavelengths to 40 arcseconds at the longest. Spitzer is still currently taking data with IRAC at 3.6 and 4.5 during the Warm Mission Era. More information on Spitzer from the cryogenic mission, and more information on Spitzer's current Warm mission, are both available.

Terminology

This archive of Spitzer data is called the Spitzer Heritage Archive, or the SHA.

An individual Spitzer observation sequence is an AOR, or Astronomical Observation Request. In certain cases (often calibration or sometimes science observations), you may also see an IER, or Instrument Engineering Request. Either one involves many individual frames.

The individual data frames that emerge, calibrated, from the Spitzer pipeline are Level 1, or Basic Calibrated Data, or BCDs.

The products that come from combining these individual data frames (such as mosaics of individual pointings) are Level 2, or post-BCD, or PBCD data.

Enhanced Products come from combining AORs or doing post processing (such as synthetic photometry from spectra or source extraction from images). These can be contributed by the community, or generated by the SSC itself.

Searching, Results, and Filters

Several search options are provided, which are documented in more detail in the section on searching. Searching by position is the most popular search.

The search results appear in up to seven tabs: AORs, Level 1, Level 2, IRS Enhanced (shorthand for "SSC-generated enhanced products for IRS"), Super Mosaics and Source Lists (shorthand for "SSC-generated enhanced products for IRAC and MIPS"), and Contributed Products (shorthand for "Contributed Enhanced Products"). Each tab provides a different look at data retrieved by your search. (See the section on understanding your search results for more information.)

Filters, either imposed on your initial search or via your results page, can provide a powerful tool for weeding down search results to the observations you want. For example, you can restrict your search to just one instrument or wavelength range, or you can restrict the entries in the tabs to be just the data products pertaining to one AOR. This same filtering mechanism can be imposed on the entire set of IRS enhanced products.

Visualization

Powerful visualization tools were important to the original Spitzer observation planning and archive tools (Spot and Leopard), and the descendents of these tools are included in the SHA. FITS images from Spitzer or other bands (or your computer) can be loaded into the viewer. The footprint of the observation can be overlaid on an image of your choice. Individual Level 1 or Level 2 products can be viewed interactively. The coverage map (e.g., how many times a given portion of sky was observed) can be overlaid on a FITS image of your choice.

See the visualization section for more on visualization.

Downloading Data

After deciding what data to download, click on the corresponding checkbox on the left side, and click "Prepare Download" to begin the packaging and data download process -- the download then gets passed to the Background Monitor for packaging. See the section on downloads for more information.

Tagging and User Preferences

There are tools here to help you re-create a search from before (that you or someone else did), called "tagging," or have the SHA remember you (and give you access to your proprietary data). See the user registration section for more information.