SDSS-V Targets of Opportunity

A package to load and cross-match targets of opportunity (ToO) for SDSS-V.

Overview

This package deals with all the aspects of loading and processing targets of opportunity. At a high level it:

• Reads one or multiple ToO input files.
• Loads new targets into catalogdb.too_target and updates the metadata of existing targets in catalogdb.too_metadata.
• Cross-matches the new targets, assigning catalogids to new targets and populating the catalogdb.catalog_to_too_target table.
• Assigns new sdss_id to the new catalogid entries. (Potentially. TBD.)
• Runs the too carton and updates targetdb.target, targetdb.carton_to_target, and targetdb.magnitude for new ToOs.
• Performs target validation.
• Generates a text file of active ToOs that can be synced to the observatories and is used by jaeger to replace targets on the fly when creating new configurations.

Datamodel

Target of opportunity files must be CSV or Parquet files with a table/dataframe that conforms to the following structure:

Column	Type	Description
too_id	int64	Unique identifier for the ToO target. [required]
fiber_type	string	Type of fiber to be used to observe the target (APOGEE or BOSS). [required]
catalogid	int64	catalogid for this target, if already matched.
sdss_id	int64	sdss_id for this target, if already matched.
gaia_dr3_source_id	int64	Unique identifier of the target in the Gaia DR3 catalog (source_id column).
twomass_pts_key	int32	Unique identifier of the target in the 2MASS catalog (pts_key column).
sky_brightness_mode	string	The sky brightness mode. Either bright or dark. [required]
ra	float64	The Right Ascension of the target in ICRS coordinates as decimal degrees. [required]
dec	float64	The declination of the target in ICRS coordinates as decimal degrees. [required]
pmra	float32	The proper motion in RA in mas/yr as a true angle (the cos(dec) factor must have been applied).
pmdec	float32	The proper motion in Dec in mas/yr as a true angle.
epoch	float32	The epoch of the ra/dec coordinates. Required when pmra/pmdec are defined.
parallax	float32	The parallax in mas.
lambda_eff	float32	The effective wavelength to calculate the atmospheric refraction correction for the target.
u_mag	float32	Sloan u' magnitude of the target.
g_mag	float32	Sloan g' magnitude of the target.
r_mag	float32	Sloan r' magnitude of the target.
i_mag	float32	Sloan i' magnitude of the target.
z_mag	float32	Sloan z' magnitude of the target.
optical_prov	string	Source of the optical magnitudes.
gaia_bp_mag	float32	Gaia BP magnitude of the target.
gaia_rp_mag	float32	Gaia RP magnitude of the target.
gaia_g_mag	float32	Gaia G magnitude of the target.
h_mag	float32	H-band magnitude of the target.
delta_ra	float32	Fixed RA offset as a true angle, in arcsec.
delta_dec	float32	Fixed Dec offset, in arcsec.
can_offset	boolean	true if the ToO is allowed to be offset. Offseting will only occur if target violates magnitude limits. [required]
inertial	boolean	If true, the proper motions for this target will be ignored (equivalent to pmra = pmdec = 0.0).
n_exposures	int16	The minimum number of exposures required for the ToO to be complete and not assigned anymore. [required]
priority	int16	The relative prioriry of this target (10: highest, 1: lowest, 0: the target will be ignored)
active	boolean	true if the target is active and should be assigned to configurations if possible. [required]
observe_from_mjd	int32	MJD from which the target is considered observable. Default to the current date.
observe_until_mjd	int32	MJD at which the target should automatically be consider inactive. If empty, the target never expires.
observed	boolean	true if the target has been fully observed and should not be assigned again. [required]
added_on	date	Date when the target was last added or modified, with the format YYYY-MM-DD. [required]

The input file(s) must contain all the columns defined above with the correct data formats.

At least one magnitude is required for target validation. If one of the Sloan magnitude is provided, all the ugriz values must be provided. A sample, valid ToO file can be found here.

The too_id must be unique across all targets of opportunity. The ingestion of new ToOs will fail if a ToO is found in the database with the same too_id.

MJDs are understood of the MJD on which the night ends. For example, a target with observe_from_mjd=60422 will attempt to observ the target from the night in which MJD 60421 crosses into 60422.

A file can be validated by using the validate_too_targets function, which will also fill nulls in some columns with default values.

from too import read_too_file, validate_too_targets
df = read_too_file('sample.csv')
validate_too_targets(df)

or via the CLI

too validate sample.csv

Note that too validate expects the schema of the input file to exactly match that of the ToO datamodel (for example, if the file contains a too_id column of type Int32 the validation will fail even if the values do not overflow int32). You can pass the flag --cast to cast the columns to the correct types. This will fail if the input dataframe cannot be coerced to the correct types. When too runs the entire pipeline, the input file is always cast, which can lead to some data precision loss.

For more details see this wiki page. To regenerate the table above, run

>>> from too.datamodel import datamodel_to_markdown
>>> datamodel_to_markdown()
| Column              | Type    | Description                                                                                            |
|---------------------|---------|--------------------------------------------------------------------------------------------------------|
| too_id              | int64   | Unique identifier for the ToO target [required].                                                       |
| fiber_type          | string  | Type of fiber to be used to observe the target [required].                                             |
...

Running too

Loading targets from a file

When a new ToO file with the format described in the previous section is available, it can be loaded into the database using the CLI command

too process <FILE>

See too process --help for more information on available options.

too process will perform the following tasks:

• Read and validate the input file(s).
• Establish a connection to the database using the command flags as modifiers. Without additional flags too will try to connect to the database sdss5db on localhost with user sdss.
• Load new targets into the tables catalogdb.too_target and catalogdb.too_metadata.
• Update data in too_metadata for existing targets.
• Cross-match the new targets, creating entries in catalogdb.catalog and catalogdb.catalog_to_too_target.
• Run the too carton.

Dumping active ToOs

To create a Parquet file with a list of ToOs that are active (ready to be observed, not expired, and not completed), use

too dump <FILE>

This command will create the Parquet file and add the bright neighbour and magnitude limit validation columns. The resulting file has the format required by jaeger to perform the replacement of science targets with ToOs.