# MaNGA Field Layout Forecast

August 2019 forecast for the on-sky field locations of MaNGA observations over the survey duration.

This figure indicates the already completed and expected field locations for observations over the course of the MaNGA Survey, based on the survey’s status as of August 2019. The forecast uses a simulation of survey operations and observing efficiency to predict the fields we will observe through the anticipated SDSS-IV completion date of June 2020. Tier-1 fields are likely to be completed assuming typical (50% clear) weather conditions over the project duration. Additional Tier-2 fields are predicted to be completed if the weather is 75% clear.

Each circular field in the figure corresponds to a MaNGA “tile.” In principle, the entire SDSS-I/II footprint can be “tiled” and is available for MaNGA observations (grey tiles). In practice, MaNGA will only be able to observe about 1/3 of this footprint (~2700 deg2). As the plot indicates, certain regions receive priority as a result of survey observing constraints, efficiency considerations, and a desire to enable overlap with ancillary surveys (some of which are labelled).

## Obtaining Target Lists

### Public MaNGA Data

Most users will be interested in the MaNGA targets that have been publicly released as part of an SDSS-IV Data Release. This information is available in the drpall summary file, which is described in the Catalogs page of the MaNGA Data Release.

### Targets Not Yet Released or Observed

We are happy to provide information about which MaNGA targets have been observed, even if they are not yet part of a data release. We would also like to support future followup efforts by providing a forecast of targets that are likely to be observed over the course of the survey (although this forecast is obviously somewhat uncertain and subject to change).

If you are interested in which MaNGA targets have been observed but not yet released, or those that we plan to observe, please follow a 2-step process. First, download the fieldProbability FITS table, which provides four columns of information for all possible MaNGA tiles in the SDSS footprint.

• MANGA_TILEID: MaNGA’s ID number for this tile
• RA: The tile’s J2000 right-ascenscion
• DEC: The tile’s J2000 declination
• TIER: Observing likelihood. TIER=0: completed (but not necessarily released). TIER=1: likely to be observed. TIER=2: will be observed only with very good weather. TIER=999: a tile that is unlikely to be observed (the grey symbols on the plot).

The fieldProbability file allows you to reproduce the plot above and determine the 3 deg diameter tiles (or fields) that have been or will be observed.

If you would like to know what galaxies are present in these tiles, please then download the MaNGA targeting catalog, ‘MaNGA_targets_extNSA_tiled_ancillary.fits’, which is described and linked to from the Targeting Page in the MaNGA section of the most recent SDSS-IV Data Release. This catalog contains a variety of information about MaNGA’s galaxy targets, including their corresponding MANGA_TILEID, which can be cross-matched to the MANGA_TILEID stored in the fieldProbability table.

The current fieldProbability table (linked above) was compiled in August 2019. It may be possible to obtain a more up-to-date version. Please contact Renbin Yan.