The Steward Alerts for Science System (SASSy) provides access to various alerts and cross-correlation with catalogs. We provide support for queries to alerts and database(s) sourced from the Galaxy List for the Advanced Detector Era (GLADE), the Gravitational Wave Galaxy Catalog (GWGC), (ad-hoc) alerts from the Laser Interferometer Gravitational-Wave Observatory (LIGO), the Transient Name Server (TNS) and the Zwicky Transient Facility (ZTF). Further information is available in the (help) and (api) sections.

These pages are adapted from the code from LCOGT (Las Cumbres Observatory Global Telescope) which delivers the MARS (Make Alerts Really Simple) website.



Any scientific publication which results from the use of this resource should include an acknowledgment of SASSy as well as the LCOGT organization. Note that the Las Cumbres Observatory Global Telescope advocates the use of their acronym, LCOGT, in scientific publications to avoid confusion with Las Campanas Observatory. If appropriate you may also consider citing their paper which defines the goals, capabilities and research interests of LCO.


Each (non-landing) page consists of the following sections:

Navigation Bar

The navigation bar is fixed to the top of the page and controls access to various sub-pages. Iconography used through the application is explained elsewhere.


Citation Header

The citation header reminds users of the purpose of SASSy and references the founding document(s) and code-base.


Page Specifics

The page specifics section is dynamically created by various RESTful routes. In the above example we see the LIGO route (which was under construction at the time). Many other routes are complete.


Footer

The footer shows the organizations that have contributed in significant ways to SASSy.



Icon Description
Navigate to the landing page
Contact the SASSy webmaster via email
Contact the SASSy webmaster via 'phone (mobile application only)
Navigate to the help page
Navigate to the API page
Section identifier
Page under construction
Activity is enabled / running
Activity is disabled / stopped


(GLADE) is the Galaxy List for the Advanced Detector Era. The SASSy database is sourced from Glade v2.3. Column headings can be viewed using the text route. The database schema is:

CREATE TABLE glade (
  id serial PRIMARY KEY,
  pgc integer,
  gwgc VARCHAR(128),
  hyperleda VARCHAR(128),
  twomass VARCHAR(128),
  sdss VARCHAR(128),
  flag1 VARCHAR(1),
  ra double precision,
  dec double precision,
  dist double precision,
  disterr double precision,
  z double precision,
  b double precision,
  b_err double precision,
  b_abs double precision,
  j double precision,
  j_err double precision,
  h double precision,
  h_err double precision,
  k double precision,
  k_err double precision,
  flag2 integer,
  flag3 integer
);

The Q3C variant database has the same table schema but a table name of glade_q3c and was created with:

CREATE EXTENSION q3c;
CREATE INDEX ON glade_q3c (q3c_ang2ipix(ra, dec));
CLUSTER glade_q3c_q3c_ang2ipix_idx ON glade_q3c;
ANALYZE VERBOSE glade_q3c;

The GLADE page of the SASSy interface consists of a list of selection criteria and a table of records. By default the table lists records in ascending order by database identifier. Earlier or later records can be viewed by using the Prev and Next links. To narrow down the results shown use the modifiers on the left. To apply modifiers simply enter the desired value into each corresponding entry widgets and click Select. Greyed-out values within entry widgets are placeholders which give some idea of the data required and format. Only the Q3C database features a cone/astrocone search.



(GWGC) is the Gravitational Wave Galaxy Catalog. The SASSy database is sourced from Gwgc VII/267. Column headings can be viewed using the text route. The database schema is:

CREATE TABLE gwgc (
  id serial PRIMARY KEY,
  pgc integer,
  name VARCHAR(128) NOT NULL,
  ra double precision,
  dec double precision,
  tt double precision,
  b_app double precision,
  a double precision,
  e_a double precision,
  b double precision,
  e_b double precision,
  b_div_a double precision,
  e_b_div_a double precision,
  pa double precision,
  b_abs double precision,
  dist double precision,
  e_dist double precision,
  e_b_app double precision,
  e_b_abs double precision
);

The Q3C variant database has the same table schema but a table name of gwgc_q3c and was created with:

CREATE EXTENSION q3c;
CREATE INDEX ON gwgc_q3c (q3c_ang2ipix(ra, dec));
CLUSTER gwgc_q3c_q3c_ang2ipix_idx ON gwgc_q3c;
ANALYZE VERBOSE gwgc_q3c;

The GWGC page of the SASSy interface consists of a list of selection criteria and a table of records. By default the table lists records in ascending order by database identifier. Earlier or later records can be viewed by using the Prev and Next links. To narrow down the results shown use the modifiers on the left. To apply modifiers simply enter the desired value into each corresponding entry widgets and click Select. Greyed-out values within entry widgets are placeholders which give some idea of the data required and format. Only the Q3C database features a cone/astrocone search.



(LIGO) is the Laser Interferometer Gravitational-Wave Observatory. The SASSy database is sourced from LIGO GW. Column headings can be viewed using the text route. The database schema is:

CREATE TABLE ligo (
  id serial PRIMARY KEY,
  name VARCHAR(32) NOT NULL UNIQUE,
  name_prefix VARCHAR(16),
  name_suffix VARCHAR(16),
  ra double precision,
  dec double precision,
  transient_type VARCHAR(64),
  discovery_date TIMESTAMP,
  discovery_mag double precision,
  filter_name VARCHAR(32),
  source_group VARCHAR(64),
  probability double precision,
  sigma double precision,
  gw_aka VARCHAR(64),
  gw_date TIMESTAMP,
  gw_event VARCHAR(32),
  before BOOLEAN NOT NULL DEFAULT False
);

The Q3C variant database has the same table schema but a table name of ligo_q3c and was created with:

CREATE EXTENSION q3c;
CREATE INDEX ON ligo_q3c (q3c_ang2ipix(ra, dec));
CLUSTER ligo_q3c_q3c_ang2ipix_idx ON ligo_q3c;
ANALYZE VERBOSE ligo_q3c;

The LIGO page of the SASSy interface consists of a list of selection criteria and a table of records. By default the table lists records in ascending order by database identifier. Earlier or later records can be viewed by using the Prev and Next links. To narrow down the results shown use the modifiers on the left. To apply modifiers simply enter the desired value into each corresponding entry widgets and click Select. Greyed-out values within entry widgets are placeholders which give some idea of the data required and format. Only the Q3C database features a cone/astrocone search.



(TNS) is the Transient Name Server. The SASSy database is sourced from Tns. Column headings can be viewed using the text route. The database schema is:

CREATE TABLE tns (
  id serial PRIMARY KEY,
  tns_id INTEGER,
  tns_name VARCHAR(64) NOT NULL UNIQUE,
  tns_link VARCHAR(128),
  ra double precision,
  dec double precision,
  redshift double precision,
  discovery_date TIMESTAMP,
  discovery_mag double precision,
  discovery_instrument VARCHAR(64),
  filter_name VARCHAR(32),
  tns_class VARCHAR(64),
  host VARCHAR(64),
  host_z double precision,
  source_group VARCHAR(64),
  alias VARCHAR(64),
  certificate VARCHAR(128)
);

The Q3C variant database has the same table schema but a table name of tns_q3c and was created with:

CREATE EXTENSION q3c;
CREATE INDEX ON tns_q3c (q3c_ang2ipix(ra, dec));
CLUSTER tns_q3c_q3c_ang2ipix_idx ON tns_q3c;
ANALYZE VERBOSE tns_q3c;

The TNS page of the SASSy interface consists of a list of selection criteria and a table of records. By default the table lists records in ascending order by database identifier. Earlier or later records can be viewed by using the Prev and Next links. To narrow down the results shown use the modifiers on the left. To apply modifiers simply enter the desired value into each corresponding entry widgets and click Select. Greyed-out values within entry widgets are placeholders which give some idea of the data required and format. Only the Q3C database features a cone/astrocone search.



The ZTF page of the SASSy interface consists of a list of selection criteria and a table of alerts. By default the table lists the 50 most recent public alerts from ZTF with no modifiers applied. Earlier results can be viewed by using the prev/next links. To narrow down the results shown, for example by date, use the modifiers on the left. To apply modifiers simply enter the desired value into each corresponding field on the modifier list and click "select". Some fields are range selections, some upper or lower bounds, and some are simple matches. For example, to show alerts with a Real/Bogus score greater or equal to 0.8, you would place "0.8" in the field marked "rb >=" and click "select". Greyed-out values within entry widgets are placeholders which give some idea of the data required and format. Column headings can be viewed using the text route (which contains a link to the gzip sources).

Viewing Details Of A Single Alert

Clicking on the id of an alert in the main table will bring you to that alert’s detail page. Here you can download the original AVRO file, view the detection triplet, lightcurve, and the data provided within the AVRO. The three cutouts are taken from the AVRO file and display the 1x1 arcmin area surrounding the alert. They are displayed using JS9, which is a web based version of DS9. You can access the menu of JS9 functions (such as scaling and analysis) by clicking "toggle JS9 menus".

Using The JSON API

JSON (Javascript Object Notation) is a widely used data serialization format. Most programming languages provide functions for reading and writing it, which makes it ideal for use in web services. Both the table and detail view can be viewed in JSON form by adding the URL modifier ?format=json. For example, to view the JSON list of alerts with a Real/Bogus score >= 0.8, you would use the following url:

https://sassy.as.arizona.edu/sassy/ztf?rb__gte=0.8&format=json

Alerts will be located within the results key. The other parameters, has_next, has_prev, pages and total are informative keys that should help you paginate through results should your query return greater than 75 alerts. Similarly, a single alert can also be viewed in JSON form:

https://sassy.as.arizona.edu/sassy/ztf/4157148?format=json

The identifier part of the URL comes from the sid key contained in the alert JSON.

Bulk Queryies Using The JSON API

With a POST query, you can submit multiple queries simultaneously, rather than leveraging the GET endpoint multiple times. To do so, simply use the base SASSy URL: https://sassy.as.arizona.edu/sassy/ztf and include a list of queries in the JSON in the POST body:

{ "queries": [ { "sid": 1, "cone": "242.3456,-5.3456,0.0007" }, { "sid": 2, "ra_gt": 242.34, "ra_lt": 242.35 } ] }

The API will return the original query information in the response to differentiate queries. It will also ignore any unsupported parameters, so you can use this to your advantage by including fields such as unique IDs (as shown above) or names of queries, which you can parse later in the response. The POST endpoint supports the same modifiers as are available on the basic GET endpoint.



ZTF uses the Apache AVRO data serialization format to distribute alerts. You can access the raw AVRO files from SASSy by using the web interface or following the avro link in the JSON views. ZTF provides a repository containing example scripts and iPython/Jupyter notebooks for working with these files.