This article describes how observing program specifications within the Roman Astronomer's Proposal Tool (APT) determine the automatic pipeline products for Roman Space Telescope General Astrophysics Survey (GAS) programs.

Specifications made in the Roman Space Telescope (Roman) Astronomer's Proposal Tool (APT) when designing a General Astrophysics Survey (GAS) program have direct impacts on the data products that will be automatically processed and archived. The design decisions are particularly important when considering the higher level data products where calibrated rate images (Level 2; L2) from each exposure are combined to make co-added mosaic (Level 3; L3) and catalog (Level 4; L4) data products. See Data Levels and Products, Prompt Products, and Data Release Products for more information about the different Roman Wide Field Instrument (WFI) data products and when they will be available to users. For a detailed description of both the APT and data product terminology, see APT program elements.

Mapping APT Terminology to Data Products

All exposures from one visit - whether at a fixed position in a mosaic pattern or taken as small dithers around the original pointing - are automatically combined and saved in a single prompt L3-VISIT product (see Prompt Products for more information about prompt data processing). Prompt, single-band L4 source catalogs and segmentation maps are created from both exposures (L2) and visits (L3-VISIT). Therefore, when designing a program in APT, it is important to choose a dither pattern which ensures the desired depth and coverage of the pointing region (see WFI Dithering for details on the available dither patterns for the WFI). 

During the planned data releases, collections of exposures within a single pass that use the same optical element will be combined into L3-SUBSET products. Thus, if two exposures with the same optical element are taken in the same pass, regardless of other parameters (e.g., exposure time), they will be combined within the same L3-SUBSET products. If, instead, exposures with different exposure times are placed in separate pass plans within an APT program, they will result in distinct L3-SUBSET products. L3-SUBSET products include only the data acquired during a single pass for each survey step of the survey plan.

During data releases, observations using the same optical element within a program will be combined into L3-FULL products, provided these differ from the L3-SUBSET products. Common program types that would result in the creation of both subset and full-depth L3 products include surveys that sweep across a large area over multiple epochs (e.g., a survey similar to the High-Latitude Wide-Area Survey), or those that stack multiple passes to create a deep image over a long time span encompassing many epochs (e.g., a survey similar to the High-Latitude Time-Domain Survey). Each L3 product generated for a data release will be accompanied by kernel-matched, multi-band catalog files and other L4 products. For data releases, these catalog files are merged into databases and may be queried via the MAST catalog service.

In the Simplified APT Program Table, we illustrate what happens for a survey where a single mosaic pattern is executed between one and three times using several pass plans. Each execution of pass plans 1 and 2 would result in two unique L3-SUBSET products, one for each optical element in the pass plans, yielding a total of four L3-SUBSET products. In contrast, executions of pass plan 3 would result in a single L3-SUBSET product that combines all three exposure times together into one  product.

To generate the L3-FULL products, all executions of pass plans 1 and 2 would be combined to create the F106 products, even though they originate from different pass plans. In addition to the data release products, each pointing in the mosaic pattern will produce a prompt L3-VISIT product for each optical element.

For additional questions not answered in this article, please contact the Roman Help Desk.