## 3 ZTF Data Processing Overview
### Access to ZTF Data  
ZTF data can be retrieved, visualized, and analyzed from the file-based products, i.e., single-exposure science images or reference images, and their catalogs or other files using the IRSA ZTF Graphical User Interface (GUI) [40]. The IRSA provides two graphical user interfaces to access ZTF data, ZTF Images services, and catalog services. IRSA/IPAC support a download platform for these data through their browseable web directory.  
Users can query the ZTF Images service using a graphical user interface to view and download ZTF images, search for astronomical objects by position, ZTF field ID, or solar system object/orbit. The IRSA image services implement a low-level search mechanism for astronomical images of metadata tables. IRSA image search services provide both single- and multi-object searches. The system's single object search function enables the user to look up astronomical bodies by their name or position. The query provides CCD-quadrant pictures that intersect these points, as well as metadata for further filtering. The result is shown in the web browser as a multicolumn table. The graphical user interface (GUI) enables previews of chosen images and interactive analysis. To perform a multi-object search, the user must manually build a sophisticated SQL query and upload it to the system. The system enables the user to load a file from a local disk or from one of the infrared scientific archive workstations.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**ZTF Public Data Released** & **Date of Releases** & **Data Acquired** \\ \hline Data Released 1 (DR1) & 8 May 2019 & ZTF-g and ZTF-r filters \\ \hline Data Released 2 (DR2) & 11 December 2019 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 3 (DR3) & 24 June 2020 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 4 (DR4) & 9 December 2020 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 5 (DR5) & 31 March 2021 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 6 (DR6) & 30 June 2021 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 7 (DR7) & 8 September 2021 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline Data Released 8 (DR8) & 3 November 2021 & ZTF-g, ZTF-r and ZTF-i filters \\ \hline \hline \end{tabular}
\end{table}
Table 3: ZTF science data product.  
Through three stages, users may retrieve, view, and evaluate catalog services using the GUI services. To begin, the user can search for an astronomical object using Single Object Search, Multi-Object Search, or All-Sky Search. The user may search for a single object using a single position and either a search radius or a box size centered on that place. After clicking on \"Run Query\", all objects and their associated light curves will be shown in a multicolumn table on a web browser based on user input. To obtain images from the multi-object search, the user must manually build a complicated query and upload it to the infrared science archive workplaces. The all-sky search retrieves counts from the full database table, whether it is in ASCII (IPAC-table) or HTML or XML format. The option perform an all-sky search does not return light curves.  
The user can click on \"Time Series Tool\" on the results page that follows the query in step 1 to obtain the light curves of user input items. The light curves for all objects may be stored in ASCII (IPAC-table) format in this multi-column table [41]. The user can click on an individual object in the list of object IDs containing lightcurve data in step 2 and transmit its light curve to the Time Series Tool. These tools provide epoch-based science photos centered on an object, and include a period finder.