2008 Summer School

Introduction

The National Optical Astronomical Observatory (NOAO) is creating an End-to-End (E2E) data system, where data flows from the telescopes, into an archive, through an image reduction pipeline, and out to the user through a portal which integrates PI-data with Virtual Observatory (VO) resources (see Smith et al. 2006). Here, we present an overview of the final stage of the NOAO's E2E sustem: the NOAO NVO Portal. The NOAO NVO Portal design, implementation, and VO client-side libraries are described elsewhere in these Proceedings (Fuentes, Miller, & Gasson 2006; Gasson, Fuentes, & Miller 2006).

Chris Miller 2008-08-04

The Discovery Views

**Figure:** The NOAO NVO Portal Sky view. The twelve surveys listed are from the NOAO Science Archive's (NSA) Survey Program. Users can click-and-hold the mouse at any location to pan around the sky, or use the zoom-bar to zoom into a region for greater detail. A mouse double-click returns imaging data at that position (see Figure ). The drop-down menus (on the left) enable users to add markers at their favorite locations and cross-match; specify the name of an object and zoom to that location; turn on/off non-NSA archives (e.g., SDSS) and search the viewable region. Users can switch between the views (at the top): Sky (default), Time, Access/Analyze, SIA (Simple Image Access), among others. Finally, each page has a tutorial, FAQ, and an email link to the NOAO help-desk.
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As described in Fuentes, Miller, & Gasson (2006), the astronomical user of the NOAO NVO Portal sees the ``views'' of the Model-View-Controller software design methodology (MVC). In Figure , we see the default view of the Portal after the use has pointed their browser to the URL of the Portal. The user sees the sky (in Aitoff projection), where the different colors each represent sky-coverage of different SIAP archives available at the Portal. To the left of the sky is a description of actions the user may take (e.g., click-and-hold to pan or use the zoom bar to zoom, etc). There is a also a drop-down menu with additional features. These and other features available to the user on the NOAO-Sky view are described in Figure .

At the top of this page is a ``View'' bar, where the user can switch between Sky, Time, Access/Analyze, Simple Image Access (SIA), among others. When ``Persistence'' (top-left) is turned on, the coordinate ranges of the viewing window are persisted across the different views. The default view when the user logs onto the Portal is the NOAO Sky (Figure ).

The NOAO NVO Portal also allows users to visualize imaging data in the temporal sense. In Figure , we show the NOAO Time view. In this view, users can use their mouse to scroll through days, months, or years to see when data were observed. Since Persistence has been turned on, the only image data displayed in Figure are those in the viewing region last seen by the user in the NOAO Sky (in this case, $7.8 \le$ RA (degrees) $\le 13.5$ and $39.8 \le$ Dec $\le 42.6$ ).

**Figure:** The NOAO NVO Portal Time view. Using the Simile Timeline (http://simile.mit.edu/timeline/) open-source application, the Portal allows for visualization of imaging data: daily, monthly, and yearly. The observation date of each image is the data source. The user can click on any set of images to display the metadata of the images taken on that date.
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**Figure:** The NOAO NVO Portal Grid view. When a user double-clicks on the NOAO-Sky, clicks ``Search'' on the region, or chooses a date and specific archive in the NOAO Time view, a GRID of imaging metadata is displayed. The GRID metadata can be sorted by clicking on the column header, viewed using VO-India's VOPlot application, or added to a cart for bulk access/analysis (see the shaded ellipses).
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The GRID View

The NOAO NVO Portal allows for data discovery, access, and analysis. Thus, when users find interesting data (either by searching on the sky or in time), the Portal enables them to select from an available list for bulk access and/or analysis. This is accomplished through the GRID view, where the imaging metadata data are displayed to the user.

In Figure , we see a listing of image data. Each column contains metadata for the image in that specific row. The Portal collects those metadata from the individual Simple Image Access (SIA) servers (e.g., SDSS or XMM, etc). Those metadata are cached at the NOAO NVO Portal to provide faster and more efficient data discovery, analysis, access, and understanding. Of course, live access to the SIA servers are still provided at the NOAO NVO Portal (using the SIA view).

Access and Analysis

**Figure:** The NOAO NVO Portal Access/Analysis view. The user has added seven images to their cart and have chosen to ``Extract Sources'' (top) on the NSA image (note the WESIX VOTable). The user is now staging the data at the Portal for bulk easy access.
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One of the main features of the NOAO NVO Portal is the ability for users to run NVO analysis services and/or access VO-compliant data in an efficient and user-friendly manner. The mechanism for this is the Portal Access/Analysis ``Shopping Cart''. Once users have added imaging data to their cart, they then have the ability to:

Send those data to the University of Pittsburgh's Web Enabled Source Identification and Xmatch service (http://nvogre.phyast.pitt.edu/gestalt).
Stage data from multiple archives (e.g., SDSS, CADC, NSA) at one location for easy bulk access.
Plot image metadata or view image FITs files (e.g., VOPlot and Aladin.

In Figure , we show the results of a user who is staging data from the Sloan Digital Sky Survey (SDSS), the INT Wide Field Survey (INT), and the NOAO Science Archive (NSA). The NSA image was used to create a source catalog, which can be identified as the WESIX VOTable in the Cart Type column. The names of the files (taken from the SIA services access references) and their download status are supplied to the user. Once the staging is finished, users can use a simple FTP client and mget to download all their data in one step. Note that the users themselves have never visited the web-sites of any of the archives or analysis services. The NOAO NVO Portal acts as a conduit to VO-compliant archives.