Advanced usage

Posting color-magnitude data to generate an HR diagram

For stellar targets we are interested in showing the HR diagram based on the color-magnitude data from a cross match to, e.g., the Gaia catalog. Currently we support only Gaia inputs on the front-end, but in a future release we may expand the notion of the HR diagram to arbitrary catalogs.

This is done by posting an Annotation to the source, with correctly formatted data. If at least one properly formatted Annotation with Gaia color-magnitude data exists on the source, an HR diagram will be rendered for it.

First let’s see how to post an Annotation using the requests package. Here is a working example:

import requests
import json

url = 'http://localhost:5000'
token = '239868fa-8307-41ad-983f-4a8180609df6'
header = {"Authorization": f"token {token}", "content_type": "application/json"}
data = {'obj_id': '2021example',
        'origin': 'cross_match_robot',
        'data': {
            'Gaia': {
                'Mag_G', 10.2,
                'Mag_Bp': 9.8,
                'Mag_Rp': 10.5,
                'Plx': 8.5
               }
            }
        }

response = requests.post(
      f'{url}/api/sources/2021example/annotations',
      header=header,
      data=json.dumps(data)
    )

Let’s look at this line by line.

The url should point to the SkyPortal instance, in this case running on a local machine.

The token should be generated for your user through the profile page. The token must have the ACL to annotate.

The header is used to pass along the SkyPortal authentication token.

The data field is a dictionary that contains information to be posted to the database. In this case the data must be formatted to comply with the Annotation API, namely it must have a valid obj_id of an existing object that is accessible to the user, it must contain a non-empty string for the origin and it should contain the annotation data, that is a dictionary with arbitrary entries.

In general, the origin field is used to enumerate the different services that would annotate each source. Each origin can only post a single Annotation to each source, but that Annotation can contain arbitrary data.

In the case of the color-magnitude plot, the system only recognizes annotations with a specific schema:

  • One of the keys in the annotation data must be named Gaia.

  • The value of that key must be another dictionary.

  • That dictionary must contain the following entries:

  • `Mag_G’, ‘Mag_Bp’, ‘Mag_Rp’, ‘Plx’.

  • All these names (including the catalog name) may be made customizable in a future release. Currently, the HR diagram is drawn only for Gaia data.

  • The names are searched ignoring case, and removing underscores. So, for example, the dictionary can contain mag_g or MagG, and would still be accepted as data for an HR diagram. Please do not include multiple data keys with indistinguishable names, i.e., both mag_g and Mag_G in the same Annotation as this will cause undefined behavior.

  • The parallax (”Plx”) is given in units of milli-arcsec.

Finally, the return value response from the request should contain a status==200 and a data dictionary with the data that was posted. If the posting was unsuccessful, the status would be 400.

Upgrading an existing Taxonomy

Taxonomies are used for classification. There is typically a sitewide taxonomy that all users of SkyPortal can see. By default, we seed a new SP database with the latest taxonomy from the Time-domain Astronomy Taxonomy (Github) (tdtax). From time to time, the latest taxonomy may be upgraded as new subclasses of sources are discovered and SP admins may need to push a new version of the taxonomy to the live application.

To upgrade to the latest tdtax, as an admin, you will need to generate a token with a “Post taxonomy” ACL. Next install the latest tdtax on your system:

pip install -U tdtax

Next, in Python:

import requests
import tdtax

tax_obj =  {'name': 'Sitewide Taxonomy',
            'provenance': 'https://github.com/profjsb/timedomain-taxonomy',
            'hierarchy': tdtax.taxonomy,
            'version': str(tdtax.__version__),
}

token = "USE-YOUR-TOKEN-HERE"
def api(method, endpoint, data=None):
    headers = {'Authorization': f'token {token}'}
    response = requests.request(method, endpoint, json=data, headers=headers)
    return response

response = api('POST',
               'URL_TO_SKYPORTAL_INSTANCE/api/taxonomy',
                data=tax_obj)

print(response.json())

You should then see something like:

{'status': 'success',
 'data': {'taxonomy_id': 9},
 'version': '0.9.dev0+git...'}

If the name of the taxonomy is exactly the same as a taxonomy already in the system, this new taxonomy will supercede that taxonomy. That is, by default it will be set to be the latest version (IsLatest = True) and shown to end users in the dropdown menu on the Source page. Older classifications will be still associated with the taxonomy_id they were originally connected to.

NOTE: in very rare cases you may wish to delete a taxonomy (e.g., if you made a typo when loading it). This should be done with extreme care: if anyone has classifications associated with that taxonomy their classifications will be lost upon delete.

Spectroscopic lines

The selection of element and galaxy lines on SkyPortal were derived from the NIST atomic database (https://www.nist.gov/pml/atomic-spectra-database) , using the methods of Gal-Yam (2019) (https://ui.adsabs.harvard.edu/abs/2019ApJ…882..102G/abstract). Telluric and Skylines were migrated from the ZTF Marshal. Element lines and galaxy lines move according to the set redshift or expansion velocity. Tellurics and skylines remain static.