## Mission Overview

### Cluster Difference Imaging Photometric Survey (CDIPS)

Primary Investigator: Luke Bouma

HLSP Authors: Luke Bouma

Released: 2019-10-04

Updated: 2022-05-04

Primary Reference(s): Bouma et al. (2019)

Citations: See ADS Statistics

## Overview

The TESS mission has been releasing full-frame images recorded at 30 minute cadence.  Using the TESS images, the CDIPS team has begun a Cluster Difference Imaging Photometric Survey (CDIPS), in which they are making light curves for stars that are candidate members of open clusters and moving groups.  They have also included stars that show photometric indications of youth.  Each light curve represents between 20 and 25 days of observations of a star brighter than Gaia RP magnitude of 16.  The precision of the detrended light curves is generally in line with theoretical expectations.

The pipeline is called "cdips-pipeline", and it is available for inspection as a GitHub repository, and should be cited as an independent software reference (Bhatti et al., 2019, http://doi.org/10.5281/zenodo.3370324).

Before using the light curves, the team strongly recommends that you become familiar with the TESS data release notes, and also consult the TESS Instrument Handbook, available at MAST (http://archive.stsci.edu/tess/).

The team has also created a catalog of target metadata, such as cluster name, cluster membership provenance, Gaia magnitudes, and parallax values.  The catalog is available as a .csv file in the Data Access section.

#### DR1 CONTENTS

The first CDIPS data release (2019-10-02) contains 159,343 light curves of target stars that fell on silicon during TESS Sectors 6 and 7.  They cover about one sixth of the Galactic plane.  The target stars are described and listed in Bouma et al. (2019).  They are stars for which a mix of Gaia and pre-Gaia kinematic, astrometric, and photometric information suggest either cluster membership or youth.

#### DR2 CONTENTS

The second CDIPS data release (2019-12-09) contains 355,380 light curves of target stars that fell on silicon during TESS Sectors 8, 9, 10 and 11.  Combined with DR1, Galactic longitudes from ~190 to 320 degrees are covered, totalling about half a million stars brighter than Gaia RP of 16.  The reduction methods used for the second release are identical to those from Bouma et al. (2019), except as noted in the CDIPS README file.  Target stars have had claims of youth in the literature.  Their light curves are amenable for studies in stellar and exoplanetary astrophysics.

#### DR3 CONTENTS

The third CDIPS data release (2020-05-07) contains 130,215 light curves of target stars that fell on silicon during TESS Sectors 12 and 13.

#### DR4 CONTENTS

The fourth CDIPS data release (2020-08-25) contains 26,956 light curves of target stars that fell on silicon during TESS Sectors 1 through 5.  Sectors 1 through 4 look away from the galactic plane, and so there are fewer young stars than in Sectors 5-13.  Some of the Orion complex is visible in Sector 5.

#### DR5 CONTENTS

The fifth CDIPS data release (2022-04-25) comprises the second year of TESS observations.  It contains 559,641 light curves of target stars that fell on silicon during TESS Sectors 14 through 26.  The target star list of young, age-dated, and age-dateable stars extends to GRP<16, and has significantly improved due to the latest parallaxes and kinematics from the Gaia satellite (see README for further details on the target selection).  A cumulative metadata file of all light curves available from Sectors 1 through 26 is available under "Catalog File" below.  This file also contains the latest information about cluster membership for any given source with a light curve.

## Data Products

Each target's lightcurve file is stored in a sub-directory based on the Sector it was observed in, as a four-digit, zero-padded string preceded by an "s".  They are further divided into sub-directories based on the camera and CCD number they are on.  For example, "s0014/cam1_ccd1/" for Sector 14 lightcurves that are on Camera 1 CCD 1.

The light curves are in a FITS format familiar to users of the Kepler, K2, and TESS-short cadence light curves made by the NASA Ames team.  Their file names follow this convention:

hlsp_cdips_tess_ffi_gaiatwo<gaiaid>-<sector>-<cam>-<ccd>_tess_v01_llc.fits

where:

• <gaiaid> = The full Gaia DR2 target id, e.g., "0002080749378172930816".
• <sector> = The Sector represented as a 4-digit, zero-padded string, preceded by an "s", e.g., "s0014" for Sector 14.
• <cam> = The camera number (1-4), e.g., "cam1" for Camera 1.
• <ccd> = The CCD number (1-4) for that camera, e.g., "ccd1" for CCD 1.

The catalog of target metadata is stored at the top level, and follows this format:

hlsp_cdips_tess_ffi_<sector-start>-<sector-end>_tess_v01_catalog.csv

where:

• <sector-start> = The first TESS Sector that has target light curves, e.g., "s0001"
• <sector-end> = The last TESS Sector that has target light curves, e.g., "s0026"

Data file types:

 _llc.fits extracted light curve file _catalog.csv catalog of source metadata such as cluster names, cluster membership provenance, Gaia magnitudes, and parallax values; NOTE: the catalog uses semi-colon (;) characters as a delimiter for columns

#### Catalog Metadata Columns

Click the blue [+] to see the list of catalog metadata.

#### Light Curve FITS File Format

Click the blue [+] to see the format of the data files FITS header.

## Data Access

#### Catalog File

The cumulative DR5 catalog file can be downloaded directly here: hlsp_cdips_tess_ffi_s0001-s0026_tess_v01_catalog.csv

Each catalog supersedes previous catalogs, however, for historical purposes previous catalogs can be found below.

The catalog file can be used to select light curves for a specific cluster, as reported by specific authors in the literature.  For example, to select all the CDIPS light curves for members of NGC 2516 reported by Cantat-Gaudin et al. (2018), one could do the following in Python (click Expand to see sample script):

This yields 4992 light curves for 876 unique stars observed over the first year of TESS, with an average of ~5 sectors per star. Given the list of source_ids, MAST can then be queried for the light curves (for example, using astroquery).

#### Astroquery Example

CDIPS data products are available in the MAST Portal and via astroquery.mast.  For those who want to download light curves for a single target, or all light curves for a given Sector, see the following Python code example below.  NOTE: There are (up to) tens of thousands of light curves for a given Sector, thus downloading all of the products can take the better part of a day, even with a good internet connection.  By default, the light curve files will be downloaded under a folder called "mastDownload" in the same working directory that you run the Python script from.  Expand the box below for a sample script.

NOTE: The final query example provided above can timeout for some users (due to internet bandwidth or traffic on the database at MAST).  If this occurs, an alternative is to use the bulk download scripts, which will download products via cURL commands given the complete list of CDIPS targets for a given Sector.

MAST Portal

A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory. Download CDIPS light curves for a few targets.

MAST Astroquery

Search for, and retrieve, CDIPS data products programmatically based on a list of coordinates or target names. You can also search by Sector.