The purpose of this document is to provide additional help for using the Spitzer Heritage Archive (SHA) itself – how to find data, investigate its properties, and download it within the web interfaces. There is also a section on how to interact with the SHA via the command-line interface.
A comprehensive introduction to the Spitzer Space Telescope, observing with it, and the properties of the instruments and data are beyond the scope of this document. Considerable documentation on these other subjects is available at the NASA/IPAC Infrared Science Archive (IRSA) website for Spitzer and its Heritage Archive.
1.2 Basic Definitions
The repository of all Spitzer data and documentation is the Spitzer Heritage Archive (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 exposures or frames. All of Spitzer's operations (planning, scheduling, processing) have been based on these units (AORs or IERs).
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.
Raw data with accurate pointing information (available for download but not directly searchable) are Level 0 data. Most users need never worry about Level 0 data.
You can search for observations by instrument or by wavelength.
IRAC, the Infrared Array Camera imaged at 3.6, 4.5, 5.8, and 8 microns.
IRS, the Infrared Spectrograph obtained low and medium resolution spectra in several ranges between 5.2 and 38 microns and imaged in two bands centered on 16 and 22 microns.
MIPS, the Multiband Imaging Photometer for Spitzer imaged at 24, 70, and 160 microns and obtained very low-resolution spectra over the range between 52 and 97 microns.
The SHA website displays sub windows, called panes. Items within each pane often appear in tabs which extend from the pane edge – click on different tabs to display different pane contents.
In several instrument contexts, users are asked about downloading ancillary files. These are generally Spitzer pipeline products that provide extra detail about the dataset beyond the minimal amount required for science analysis. An example would be the calibrated first difference images for MIPS-24. The information in these images is integrated into the BCD, but the first difference image gives more detail on soft saturated regions in the image.
Also available are Enhanced Products that come from combining AORs or doing post processing (such as synthetic photometry from spectra or source extraction from images). These are very powerful ways to get started on using Spitzer data in your science pretty much straightaway. Enhanced products generated by the Spitzer Science Center (SSC) are returned in a tab separately from the substantial contributed enhanced products that were delivered by the community to the SSC and IRSA (and continue to be delivered to IRSA); these contributed enhanced products can include mosaics, photometry, spectra, and data from telescopes other than Spitzer.
1.3 Acknowledgements
If you use the SHA in your research, we request that you use the following acknowledgement in your paper, where you can include or omit the “in part” as appropriate:
This work is based [in part] on observations made with the Spitzer Space Telescope, obtained from the NASA/ IPAC Infrared Science Archive, both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.
We also note here (but you do not have to include this in your paper) that IRSA and the Spitzer Heritage Archive utilize technology developed for the Virtual Astronomical Observatory (VAO), funded by the National Science Foundation and the National Aeronautics and Space Administration under Cooperative Agreement AST-0834235.
