IRSA Viewer: Data Collections

Introduction

Data Collection Explorer

Searching

On the left, you see a table entitled, "Choose Data Collection." This table is like any other table here in that it is searchable, sortable, filterable, etc. Each row here corresponds to a data set that is currently available within this tool.

If you select a row in this table by clicking on it, then the contents of the image on the right changes in response. If the dataset is all-sky (like AKARI or IRAS/ISSA), then no polygons appear on the right. If the dataset covers just portions of the sky, then the polygons on the right indicate the sky coverage of the dataset. In the example above, the 2MASS LGA is selected on the left, and the small, yellow polygons on the right show the footprints of the individual images that make up the LGA survey.

⚠ Tips and Troubleshooting:

• The HiPS image as well as the MOC are customized to each data set, so it may take a few seconds to update. For some data sets with many small footprints (e.g., z0MGS), it may take longer to render the MOC than others.
• If you know exactly what you want, you don't have to wait for the MOC to render before you search -- just type in your target and 'Search'!
• If no MOC is shown on the HiPS image, the data set is all-sky (or there is a bug!)... if it is an all-sky data set, it should say "Covers whole sky" in the title of the search portion of the screen on the right.
• The i with a circle () in the table is a link to more information about the data collection. You can also click on the "Documentation..." link in the search box on the right.
• The image on the right is a HiPS image which has the MOC for the data set overlaid. As described in the discussion of the layers icon, specifically that on the HiPS MOC, you can change how the MOC is rendered; here it is attempting to draw the MOC as outlines, and its accuracy will be improved the closer you zoom in.
• If you want more screen 'real estate' to work with, click on "<< Hide" in the upper left to collapse the Data Collection table and maximize the space with the image and survey overlay.

To select a target, you can type in a name and have NED or Simbad resolve it into coordinates, type in coordinates in any of a variety of units, or click on the image to select a target based on your mouse position. This is just like entering a target anywhere else in the tool, or interactive target refinement elsewhere in the tool.

Enter a search radius, and click "Search" to start the search.

Results

The table at the bottom is a list of the observations that it found consistent with the specified search. This table is searchable and sortable just like all the other tables here. The "Data Help" button at the top left of the data table will take you to more information about the data set. The image (or plot in some sitautions) in the upper left is a preview of the selected row in the table. Pin the image to hold onto it if you want.

The plot on the right is often initially relatively uninteresting, because it has just the positions of the data products it has retrieved. It's a plot like any other in this tool, so you can make it plot other things.

⚠ Tips and Troubleshooting:

• The coverage image, which is by default on the left, under the window showing data product previews, will show polygons corresponding to the data products' coverage. However, if there are more than 5,000 results, the tool has too many polygons to manage, and will fall back to showing just the positions of the data products it has retrieved. (Whether that is the central point or the lower left corner of the image depends on the data product itself.)

Downloading Data