## Mission Overview

### Hubble UV Legacy Library of Young Stars as Essential Standards ("ULLYSES")

Primary Investigator: Julia Roman-Duval

HLSP Authors: See complete list of HLSP authors.

Released: 2020-11-05

Updated: 2023-03-21

Primary Reference(s): Roman-Duval et al. 2020

Read Me | DR6 Release Notes

Source Data:

New Observations:

HST Proposals 1609016092160941609516096

Archival Observations (click "Expand All" to see):

## Overview

The Hubble UV Legacy Library of Young Stars as Essential Standards ("ULLYSES") is a Director's Discretionary program devoting ~1,000 HST orbits to the production of an ultraviolet spectroscopic library of young high- and low-mass stars in the local universe. The ULLYSES program uniformly samples the fundamental astrophysical parameter space for each mass regime -- including spectral type, luminosity class, and metallicity for massive OB stars (in the Magellanic Clouds and two other lower-metallicity nearby galaxies) and the mass, and disk accretion rate for low-mass T Tauri stars (in eight young Galactic star forming regions). The data will be gathered over a three-year period, from Cycle 27 through Cycle 29 (2020-2022). The data products are combined from individual, extracted and calibrated spectra obtained HST/COS, HST/STIS, and FUSE. Both archival HST and new HST observations obtained through the ULLYSES program are used. Additional products are created using ground-based LCOGT observations.

In addition to the MAST HLSP webpage here, you can read more about ULLYSES on their team page: https://ullyses.stsci.edu/index.html.  You can find out detailed information on the observations, the data processing, and access their spectral table.

#### Data Release 6 (21 Mar. 2023)

ULLYSES Data Release 6 (DR6) consists of high-level science products (HLSPs) for 59 new ULLYSES targets and updated HLSPs for 339 targets previously released in previous DRs, for a total of 398 ULLYSES targets to date. Products are also provided for 9 companion targets present in STIS long-slit observations. DR6 includes improved FUSE spectra, additional timeseries spectra, the final epochs of monitoring T Tauri stars, and new massive stars in low-metallicity galaxies. More details can be found in the ULLYSES Data Release 6 page.

#### Data Release 5b (15 Nov. 2022)

ULLYSES Data Release 5b (DR5b) consists of high-level science products (HLSPs) for 17 new ULLYSES low-mass targets. Data releases typically include reprocessed HLSPs from previous releases, but DR5b is limited to only new products for these 17 T Tauri stars. In addition, a new MAST search form that provides ULLYSES data, stellar parameters, and observational information is now available. This new search form will be the main platform to query and download ULLYSES data going forward.

#### Data Release 5 (28 June 2022)

ULLYSES Data Release 5 (DR5) consists of high-level science products (HLSPs) for 75 new ULLYSES targets and updated HLSPs for 250 targets previously released in DRs 1-4, for a total of 325 ULLYSES targets to date. Products are also provided for 9 companion targets present in STIS long-slit observations. The HLSP creation code is now available to the public. More details can be found in the ULLYSES Data Release 5 page.

#### Data Release 4 (14 Dec 2021)

ULLYSES Data Release 4 (DR4) consists of high-level science products (HLSPs) for 25 new ULLYSES targets and updated HLSPs for 226 targets previously released in DRs 1-3, for a total of 251 ULLYSES targets to date. Products are also provided for 8 companion targets present in STIS long-slit observations. More details can be found in the ULLYSES Data Release 4 page.

#### Data Release 3 (31 Aug. 2021)

Data Release 3 (DR3) consists of high-level science products (HLSPs) for 90 new ULLYSES targets and updated products for 137 targets previously released in DRs 1 and 2, for a total of 227 ULLYSES targets to date. HLSPs are also provided for six companion targets present in STIS long-slit observations. DR3 includes two new product types – time-series spectra and WFC3 drizzled images – and introduces LCOGT (Las Cumbres Observatory Global Telescope) data for an initial subset of ULLYSES T Tauri stars.

#### Data Release 2 (17 Mar. 2021)

The second ULLYSES data release consists of coadded and abutted high-level science products for 24 new ULLYSES targets in addition to updated HLSPs for 115 targets previously released in DR1 for a total of 139 ULLYSES targets. 126 targets are massive stars and 13 are T Tauri stars. An additional 5 non-ULLYSES targets are included as well, detailed on the ULLYSES Data Release 2 page.

#### Data Release 1 (05 Nov. 2020)

The first data release consists of multiple spectra for 115 massive stars in the Large and Small Magellanic Clouds. 43 of these 115 stars were recently observed with COS and STIS as part of the ULLYSES program; 8 of these 43 also have archival COS and STIS data. The remaining 72 targets have full UV coverage from archival programs (see the ULLYSES target lists for the LMC and SMC).

## Data Products

For a full description of how the HLSPs were created, please see the Data Description page on the ULLYSES website.

The spectra have the following file naming convention:

hlsp_ullyses_<telescope>_<instrument>_<target>_<opt_elem>_<version>_<product-type>

where:

• <telescope> = one or more values representing the telescope(s) used to create the spectrum, described more below
• <instrument> = one or more values representing the instrument(s) used to create the spectrum, described more below
• <target> = the name of a star in the ULLYSES program, all lowercase and no underscores allowed
• <opt-elem> = one or more optical elements representing the grism(s) used to create the spectrum, described more below
• <product-type> = the type of spectral product, described more in the table below
• <version> = the data release identifier, e.g., "dr1", "dr2", etc.

#### Additional Information On Data File Names and Types

Description Telescope Instrument Optical Element Product Type ULLYSES HLSP Level
Custom calibrated STIS 1D spectra. hst stis

g230l

g430l

g750l

spec.fits 0
STIS custom calibration parameter files. hst stis

g230l

g430l

g750l

spec.yaml 0
STIS echelle single grating, where the orders have been extracted and merged. hst

stis

stis

stis

stis

e140h

e230h

e140m

e230m

mspec.fits 1
Combined spectra, with common instrument and grating, and in some cases with different cenwave settings. hst

cos

cos

cos

cos

stis

stis

stis

stis

stis

stis

stis

g130m

g160m

g185m

g230l

e140h

e140m

e230h

e230m

g230l

g430l

g750l

cspec.fits 2
Combined spectra, with common instrument, different gratings and cenwave settings, and grouped by resolution.

fuse

fuse

hst

hst

hst

hst

fuv

fuv

cos

stis

stis

stis

lwrs

mdrs

g130m-g160m-g185m

e140h-e230h

e140m-e230m

g230l-g430l-g750l

cspec.fits 3
All instruments and settings abutted together.

hst

hst

hst-fuse

cos-stis

cos-stis

fuse-cos-stis

uv

uv-opt

uv-opt

preview-spec.fits 4
Exposure-level time-series spectra.

hst

hst

lcogt

cos

cos

04m

g130m

g160m

v-ip

tss.fits

5
Subexposure-level time-series spectra.

hst

hst

cos

cos

g130m

g160m

split-tss.fits

5
WFC3 drizzled images.

hst

wfc3

wfc3

wfc3

wfc3

wfc3

f225w

f275w

f336w

f475w

f814w

drc.fits 6

Data file types:

 _cspec.fits Spectra combined from multiple gratings or instruments. _mspec.fits Spectra combined from multiple STIS echelle orders. _preview-spec.fits All instruments and settings abutted together. _spec.fits Custom calibrated STIS spectra. _spec.yaml STIS custom calibration parameter files.

## Data Access

ULLYSES products are available in the MAST Mission Search (mission-specific searches), the Portal (web-based, cross-mission search interface) and Astroquery (Python package to search for and download files from Python scripts you write).  You can also access them through a spectral table available on the ULLYSES team webpage.  We recommend most users start with the Mission Search Form through the browser or the programmatic access through its API and astroquery.mast.

• ### Missions Search

A web-based interface for searching by mission-specific metadata. Also available through astroquery.mast.
• ### MAST Portal

A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory.
• ### MAST Astroquery

Search for, and retrieve, ULLYSES data products programmatically based on a list of coordinates or target names.

### LMC Targets

Load table of all LMC targets.

### SMC Targets

Load table of all SMC targets.

### Low Z

Load table of all low-metallicity targets.

### T Tauri Stars

Load table of all T Tauri targets.

## Citations

Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work.

Note: These HLSP data products are licensed for use under CC BY 4.0.