Restructuring the Marshall Database Scheme

The transientBucket table has become a little unruly and can be difficult to manage and navigate. I’ve therefore sliced this table up in to various sub-tables. Incidentally this has helped me generalise the marshall so that the same core-tables can be used by multiple survey webapps, each survey having its own set of book-keeping tables much like the current pesstoObjects table. The new core tables are:

  • marshall_sources - one row for each unique source in the marshall with RA, DEC and Sherlock Classification
  • marshall_sources_discoveries - discovery information for each transient from each of the surveys that have ‘discovered’ it
  • marshall_sources_photometry - all survey photometry info for each transient, including non-detection limits
  • marshall_sources_spectra - all spectral info for each transient
  • marshall_sources_related_files - a list of related files associated with each transient

A Study Of Galaxy Completeness Limits In NED

A Study Of Galaxy Completeness Limits In NED

I wanted to generate a few plots to show the extent of the incompleteness and the anisotropy of the sample of galaxies catalogued in NASA/IPAC Extragalactic Database (NED). Below is plot of a northern section of the probability map of the gravitational wave GW1509141, overlaid with the PS1 survey footprint and all galaxies catalogued in NED within that footprint. The sharp drop in galaxy counts below dec \(\sim-3^{\circ}\) serves to reveal the boundary of SDSS DR62.

Apart from SDSS there are three other main survey footprints:
  1. WINGS (WIde-field Nearby Galaxy-cluster Survey) survey of a complete, X-ray selected sample of galaxy clusters in the redshift range 0.04–0.07.
  2. The Las Campanas Redshift Survey (LCRS) consists of 26,418 redshifts of galaxies selected from a CCD-based catalog obtained in the R band. The survey covers over 700 deg2 in six strips, each 1.5deg x 80deg, three each in the north and south Galactic caps
  3. The Cosmological Evolution Survey (COSMOS). From the COSMOS website:
The Cosmological Evolution Survey (COSMOS) is an astronomical survey designed to probe the formation and evolution of galaxies as a function of both cosmic time (redshift) and the local galaxy environment. The survey covers a 2 square degree equatorial field with imaging by most of the major space-based telescopes and a number of large ground based telescopes, with many ongoing surveys. Over 2 million galaxies are detected, spanning 75% of the age of the Universe

Comparing Equal-Area Samples of Galaxies

Using two equal-area samples of galaxies catalogued in NED, one within the SDSS footprint and one outside of the SDSS footprint, we can compare the completeness of the samples. I decided to repeat this process 3 times for 3 different pairs of sample areas with search radii of \(2.5^{\circ}\) at the coordinates shown in the tables.

One

Parameter SDSS Non–SDSS Total Sources w/ Axis Measurements
RA 140.0 153.0 1673 1512
DEC 6.0 –12.0 519 80

Two

Parameter SDSS Non–SDSS Total Sources w/ Axis Measurements
RA 149.0 152.0 31047 4091
DEC 2.0 –7.0 1102 999

Three

Parameter SDSS Non–SDSS Total Sources w/ Axis Measurements
RA 132.0 154.0 1223 1120
DEC 4.0 –16.5 171 63

Conclusions

As you can see the depth of completeness of catalogued galaxies within SDSS far outstrip the completeness of those catalogued outside. This shows the importance of pushing ahead with all-sky surveys (e.g. PanSTARRS and LSST).

  1. the previous placeholder name for GW150914 was G184098  ↩
  2. DR6 is the highest SDSS release in NED as of 20160405  ↩

How to ... parse data from the Transient Name Server webpages

How to ... parse data from the Transient Name Server webpages

The Transient Name Server provides a search page, which lists all of the transients currently in the name server. The URL of this page can be manipulated either through the HTML form provided or manually via the URL request parameters to return a filtered set of transients.

Here’s the search URL and the parameters we can use to search the TNS:
url="http://wis-tns.weizmann.ac.il/search",
params={
   "page": "1",
   "name": "",
   "name_like": "0",
   "isTNS_AT": "all",
   "public": "all",
   "unclassified_at": "0",
   "classified_sne": "0",
   "ra": "",
   "decl": "",
   "radius": "",
   "coords_unit": "arcsec",
   "groupid[]": "null",
   "type[]": "null",
   "discoverer": "",
   "date_start[date]": "",
   "date_end[date]": "",
   "discovery_mag_min": "",
   "discovery_mag_max": "",
   "redshift_min": "",
   "redshift_max": "",
   "spectra_count": "",
   "associated_groups[]": "null",
   "display[redshift]": "1",
   "display[hostname]": "1",
   "display[host_redshift]": "1",
   "display[source_group_name]": "1",
   "display[programs_name]": "1",
   "display[isTNS_AT]": "0",
   "display[public]": "1",
   "display[spectra_count]": "1",
   "display[discoverymag]": "1",
   "display[discmagfilter]": "1",
   "display[discoverydate]": "1",
   "display[discoverer]": "1",
   "display[sources]": "0",
   "display[bibcode]": "0",
   "num_page": "40",
   "edit[type]": "",
   "edit[objname]": "",
   "edit[id]": "",
   "sort": "desc",
   "order": "discoverydate"
}
To parse the TNS data in a sensible and efficient manner I want to:
  • display all columns in the table by setting all display[XXX] parameters equal to 1.
  • order the results by discovery date by setting "order": "discoverydate"
  • display 1000 results at a time ("num_page": "1000") and paginate through them with the page parameter
  • set a lower limit to the discovery date and do not parse before that date. Currently I select everything in the last two years by setting "date_start[date]": "2014-01-28" and setting "date_end[date]": "2100-01-01" (i.e. some arbitrary time in the future).
Here’s a script you can use to parse the name-server. Please use with care and don’t overload the name-server by hitting it more than a few times an hour with this script.

Automation

The PESSTO Marshall’s TNS importer runs once an hour. Once the importer has run the Marshall’s name updater script runs to make any (a) SN designation or (b) AT name the master name for the object. …

NED - An Extragalactic Database

These summary notes have been lifted from the NED webpages.


NED’s ongoing mission is to provide a comprehensive and easy-to-use, multi-wavelength fusion of fundamental data for all known (cataloged and published) objects beyond the Milky Way. As new observations are published, they are cross-identified or statistically associated with previous data and integrated into a unified database to simplify queries and retrieval. Note, these high fidelity cross-ids are non-trivial1.

The Data Available

Available data include positions, redshifts, morphological and spectral types, sizes, photometry, images, spectra, distances, diameters, cross-IDs, associations, reference abstracts, and detailed notes. Derived quantities include Galactic extinction, velocity corrections, Hubble flow distances and scales, cosmological corrections, quick-look luminosities, and spectral energy distributions (SEDs). Updates to the public database occur approximately every three months after periods of data entry, quality assurance, and testing. Many of the individual catalogs integrated into NED are available from CDS (Centre données astronomiques de Strasbourg)

Links to External Cosmology and Extinction-Law Calculators

There are links to five different Cosmology Calculators enable you to calculate various cosmological parameters and to five different Extinction Calculators enable you to calculate Galactic extinction

Unprocessed Catalog Sources versus NED Objects

Note NED’s Search Objects, With Unprocessed Catalog Sources option allows a search similar to the “Near Position” search, but optionally returns unprocessed catalog sources from very large catalogs that have yet to be cross-matched with NED. A Status of S (catalog source) indicates an astronomical observation which has not yet been fully integrated into NED’s representation of the hierarchy of the universe. A Status of O (NED object) indicates a physical thing or a group of things in the universe, or a region of space, which has been cross-identified or associated by NED with one or more vetted catalog sources. The Status column returned by the Search Objects, With Unprocessed Catalog Sources service indicates the NED processing status. Note when you return to NED in the future, you may find that some entries previously identified as S have been promoted to O or added as cross-identifications to other entries, due to new runs or refinements of NED’s cross-matching algorithms.

Current Object Counts in NED

Using NED

World Wide Web: Automated access to NED’s Web (http) services via computer programs and scripts is supported. Batch Mode: designed for searches that will return typically more than a few hundred objects. Using this mode simply involves submitting to NED via email a “batch form” containing a list of objects or positions. When NED has completed your batch job, you will receive an email message with information on using FTP to retrieve the results. NED will also process long lists of objects through its Batch Job option - the limit on the size of batch jobs is 3,000 objects.

Query Types

Objects can be queried:
  • By Name,
  • Near Name or
  • Near Position (cone search), and
  • With Unprocessed Catalog Sources (to include very large catalog sources that are not yet cross-matched with NED objects).
You may specify a search radius of up to 300 arcminutes. (i.e. 5 deg radius)

NED VO/XML Services

NED web services use the HTTP GET protocol whenever possible, with query filters encoded as URL name–value pairs.

Conesearches

To construct a conesearch URL use the format:
http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?search_type=Near+Position+Search&of=xml_main& RA=Value&DEC=Value&SR=Value
Note:
  • RA and DEC are in decimal degrees (J2000) and
  • SR (search radius) is in degrees.
For example to query objects within 15 arcminute radius around M 83 use the URL:
http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?search_type=Near+Position+Search&of=xml_main& RA=204.253833&DEC=-29.865750&SR=0.25
Results are returned in VO Table XML format.

nph-objsearch

The main search program, nph-objsearch, has a number of options that affect the results.
of
The output format option. When set to value xml_all it returns a VOTable containing nested tables (“table of tables”), each containing a specific type of source data.
Specific data types are also available separately by specification of xml_main (main source table), xml_names (source cross-IDs), xml_posn (source position, with uncertainties when available), xml_basic (Basic Data), and xml_extern (links to External Resources at the source position).
extend
extend=no requests data for only the object name specified by objname. extend=yes also returns data for objects associated to the queried objname, for example, H II regions within a galaxy or members of a galaxy group.

nph-datasearch

search_type
examples include search_type= Diameters , search_type= Redshifts , search_type= Notes , search_type= Positions

Types of NED Searches

NED will return only 50,000 objects with a Near Position search. Searches that are likely to return more than 50,000 objects are best done with NED Batch Jobs. Choose the format of your tabular output list:
  • preformatted HTML text
  • an HTML table of all data for all the returned sources,
  • an ASCII bar-separated variable table of the list of sources,
  • an ASCII tab-separated variable table of the list of sources,
  • an XML table of the list of sources,
  • an XML table of the returned source names (cross-identifications),
  • an XML table of the returned source positions (equatorial B1950 and J2000, ecliptic B1950 and J2000, Galactic, and supergalactic)
  • an XML table of the returned source Basic Data,
  • an XML table of the returned source quantities derived from its redshift (if any),
  • an XML table of links to external archives and services with data for the returned source,
  • an XML table of all data for the returned sources,
Note you can change the way in which redshifts are displayed

Search Objects, With Unprocessed Catalog Sources

This search allows you to search NED’s master list of astronomical objects for entries near a given position.

Search with a List of Positions

WIth near position lists you can cut-and-paste up to 500 positions, one per line, of the object(s) you wish to search for in the “Input List Equatorial J2000 Positions or Object Names” box. You may choose a search radius up to 30.0 arcsec. The output you can select includes:
  • Identifications
  • Basic Data
  • Data Counts and Links
  • Classifications
  • Photometry
  • Diameters

  1. A galaxy pair resolved at 2 μm may be unresolved at 24 μm. Astrophysics makes sources look different as a function of wavelength; for example, in dusty starburst galaxies, centroids in the IR often do not match those in the UV. In addition, objects reside in a hierarchical Universe: galaxies contain components (AGNs, supernovae, star clusters, HII regions, etc.); galaxies occur in pairs, group and clusters; and clusters string together in superclusters separated by vast voids.  ↩