MPT Catalogs - Examples

Several examples of input catalog formats to be used in the MSA Planning Tool are presented.

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The NIRSpec MSA Planning Tool (MPT) uses Catalogs to plan observations for MOS spectroscopy or target acquisition that uses the NIRSpec micro-shutter assembly. These source Catalogs used in the MPT are ASCII files and can be imported in a few different formats. If the Catalog format is different than what is specified when loaded into MPT, then errors in the automatic column recognition can occur. For optimal ingest of Catalogs into MPT, catalog files should be created with a few simple rules in mind:

  • Two columns are required for the equatorial celestial coordinates (J2000) RA and Dec for each source. These can be expressed in units of degrees or in hexadecimal format. 
  • It is useful to associate each source position with an integer ID in the first column of the Catalog. The ID should be an integer value from 1 up to 1e6 (1,000,000). The ID will be encoded into the name of the Level 3 output products from the pipeline,
  • It may be useful for at least one column to have source fluxes or magnitudes (optional).
  • Optionally include a column called Stellarity with a value from 0 to 1 for increasingly point-like sources. Use a value of -1 for unknown source stellarity. This will be used by the pipeline for processing the sources. Default processing is for point-like objects.
  • The Catalog may optionally contain a header line at the top of the file indicating column names separated by whitespace. The header line must begin with a "#".  
  • Using recognized labels will assist ingest and filtering of the Catalog when making subset lists called Candidate Sets. Some recognized labels are ID, RA, DEC, Size, Redshift, Reference, Stellarity, Magnitude, Magnitude error, R50, Number, Label, Weight, and FWHM. Most of these are optional columns.
  • The Catalogue must have a radial extent from its center position of less than 1 degree. APT will provide a warning message if the catalogue is larger than 1 degree. 

Here we provide some examples of acceptable Catalogs. Only the first 3 sources in each Catalog are listed as examples.

NOTE: The column Reference in the Catalog examples below is used to designate a source as a candidate NIRSpec target acquisition reference object. Inclusion of this column is not needed for proposals, but will be required for the first flight-ready program update for NIRSpec MOS observations or MSA target acquisition observations. 



White space separated values

Each column element has to be separated by a white space. Example catalogs 1–6 are included below.


Catalog 1

# RA

Dec

53.16054039

-27.79774121

53.17103742

-27.78765924

53.16553235

-27.77259145


Catalog 2

# ID    

RA

Dec

1

53.16054039

-27.79774121

2

53.17103742

-27.78765924

3

53.16553235

-27.77259145


Catalog 3

# RA

Dec

Weight

53.16054039

-27.79774121

100

53.17103742

-27.78765924

1

53.16553235

-27.77259145

100


Catalog 4

# RA

Dec

MAG_F160W

MAGERR_F160W

53.16054039

-27.79774121

17.85

0.01

53.17103742

-27.78765924

19.21

0.10

53.16553235

-27.77259145

20.10

0.05


Catalog 5 (with added columns required for MOS Program Updates)

# RA

Dec

MAG_F160W

MAGERR_F160W

REFERENCE

NRS_F110WNRS_F140XNRS_CLEAR

53.16054039

-27.79774121

17.85

0.01

FALSE

19.2218.5518.30

53.17103742

-27.78765924

19.21

0.10

FALSE

19.9719.3218.98

53.16553235

-27.77259145

20.10

0.05

TRUE

21.2020.9620.23


Catalog 6 (with added stellarity column to instruct DMS how to process source spectra)

# RA

Dec

MAG_F160W

MAGERR_F160W

Stellarity

53.16054039

-27.79774121

17.85

0.01

0.15

53.17103742

-27.78765924

19.21

0.10

0.33

53.16553235

-27.77259145

20.10

0.05

0.98



CSV - comma separated values

Each column element has to be separated by a comma (,).  Example catalogs 1 and 2 are included below.


Catalog 1

# RA

,

Dec

53.16054039

,

-27.79774121

53.17103742

,

-27.78765924

53.16553235

,

-27.77259145


Catalog 2

# ID    

,

RA

,

Dec

1

,

53.16054039

,

-27.79774121

2

,

53.17103742

,

-27.78765924

3

,

53.16553235

,

-27.77259145



TSV - tab separated values

Use the tab key on a your keyboard to separate the column elements in each column. An example catalog is included below.


Catalog 1

# RA

<tab>

Dec

53.16054039

<tab>

-27.79774121

53.17103742

<tab>

-27.78765924

53.16553235

<tab>

-27.77259145



VOT - Virtual Observatory table

VOTables are XML format files that contain astronomical data. More information on the format for VOT tables can be found in the website of the International Virtual Observatory Alliance

Using Aladin

The Aladin tool can export catalogs to VOTable. In order to export a catalog already imported in Aladin as a VOTable, with the Aladin viewer active simply do:

File >> Export planes (FITS, VOTables, ...) 

and select the output name for the catalog.  

Using astropy.io.votable

The astropy sub package astropy.io.votable allows users to read and write VOTable XML files.

Example

Use the file vot-catalog.xml as an example catalog in the VOT format.




Notable updates
  •  
    Reviewed and minor clarification about program updates and stellarity values.

  •  
    Added an example for MOS program updates
Originally published