NASA ADS API Guide

Overview

The NASA Astrophysics Data System (ADS) is a digital library operated by the Smithsonian Astrophysical Observatory under a NASA grant. It is the primary bibliographic database for astronomy and astrophysics, also covering significant portions of physics, geophysics, and related disciplines. ADS indexes over 16 million records and provides access to full-text articles, citations, and usage metrics.

ADS is indispensable for astronomers and physicists. Nearly every paper in astrophysics is indexed in ADS, and the system provides powerful search capabilities including full-text search, citation and reference tracking, author disambiguation, and object-level queries (search by astronomical object name). The database integrates with SIMBAD, NED, and other astronomical databases to link publications to the celestial objects they study.

The ADS API requires a free API token and supports 3,000 requests per day. It returns JSON and supports a rich query language with field-specific searches, boolean operators, and positional queries.

Authentication

Authentication is required via a free API token. Register at https://ui.adsabs.harvard.edu/user/settings/token to generate your token. Include it in every request as a header:

Authorization: Bearer YOUR_ADS_API_TOKEN

Tokens do not expire but can be regenerated from the settings page. Each token is associated with a user account and is subject to per-account rate limits.

Core Endpoints

Query: Search the ADS Database

• URL:

  GET https://api.adsabs.harvard.edu/v1/search/query

• Parameters:

  Param	Type	Required	Description
  q	string	Yes	Search query (ADS query syntax with field qualifiers)
  fl	string	No	Fields to return (comma-separated: title, author, year, bibcode, doi, citation_count, abstract, etc.)
  rows	integer	No	Results per page (default: 10, max: 2000)
  start	integer	No	Pagination offset (default: 0)
  sort	string	No	Sort field and order (e.g., citation_count desc, date desc)
  fq	string	No	Filter queries for faceting (e.g., database:astronomy)

• Example:

  curl -H "Authorization: Bearer YOUR_TOKEN" \
       "https://api.adsabs.harvard.edu/v1/search/query?q=gravitational+waves&fl=title,author,year,bibcode,citation_count,doi&rows=10&sort=citation_count+desc"
  

• Response: JSON with

  response.numFound

  (total hits) and

  response.docs

  array. Each doc contains the requested fields. The

  bibcode

  is the unique ADS identifier (19-character string encoding journal, year, volume, and page).

Author Search: Find Researcher Publications

• URL:

  GET https://api.adsabs.harvard.edu/v1/search/query

• Parameters:

  Param	Type	Required	Description
  q	string	Yes	Author query using author: or first_author: fields
  fl	string	No	Fields to return
  rows	integer	No	Results per page
  sort	string	No	Sort order

• Example:

  curl -H "Authorization: Bearer YOUR_TOKEN" \
       "https://api.adsabs.harvard.edu/v1/search/query?q=author:%22Hawking,+S%22&fl=title,year,bibcode,citation_count&rows=20&sort=citation_count+desc"
  

• Response: JSON with matching publications by the specified author.

Object Search: Find Papers About Astronomical Objects

• URL:

  GET https://api.adsabs.harvard.edu/v1/search/query

• Parameters:

  Param	Type	Required	Description
  q	string	Yes	Object query using object: field (e.g., object:"M31")
  fl	string	No	Fields to return
  rows	integer	No	Results per page

• Example:

  curl -H "Authorization: Bearer YOUR_TOKEN" \
       "https://api.adsabs.harvard.edu/v1/search/query?q=object:%22Sgr+A*%22&fl=title,author,year,bibcode,citation_count&rows=10&sort=date+desc"
  

• Response: JSON with publications related to the specified astronomical object.

Metrics: Paper and Author Metrics

• URL:

  POST https://api.adsabs.harvard.edu/v1/metrics

• Parameters:

  Param	Type	Required	Description
  bibcodes	array	Yes	Array of ADS bibcodes (JSON body)
  types	array	No	Metric types: basic, citations, indicators, histograms

• Example:

  curl -X POST -H "Authorization: Bearer YOUR_TOKEN" \
       -H "Content-Type: application/json" \
       "https://api.adsabs.harvard.edu/v1/metrics" \
       -d '{"bibcodes": ["2016PhRvL.116f1102A"], "types": ["basic", "citations", "indicators"]}'
  

• Response: JSON with citation metrics, h-index, g-index, read counts, and citation histograms for the specified papers.

Rate Limits

The API allows 3,000 requests per day (resets at midnight UTC) and 15 requests per second burst limit. If limits are exceeded, the API returns HTTP 429 with

X-RateLimit-Reset

header. For large bibliometric analyses, use the ADS bulk export or the myADS notification system. Monitor usage via

X-RateLimit-Remaining

response headers.

Common Patterns

Literature Review in Astrophysics

Search for recent highly-cited papers on a topic:

curl -H "Authorization: Bearer YOUR_TOKEN" \
     "https://api.adsabs.harvard.edu/v1/search/query?q=dark+energy+AND+year:2023-2026&fl=title,author,year,bibcode,citation_count,doi,abstract&rows=20&sort=citation_count+desc"

Build an Author's Publication Profile

Retrieve complete publication list with metrics:

# Get publications
curl -H "Authorization: Bearer YOUR_TOKEN" \
     "https://api.adsabs.harvard.edu/v1/search/query?q=author:%22Perlmutter,+S%22&fl=title,year,bibcode,citation_count&rows=200&sort=date+desc"

# Get aggregate metrics
curl -X POST -H "Authorization: Bearer YOUR_TOKEN" \
     -H "Content-Type: application/json" \
     "https://api.adsabs.harvard.edu/v1/metrics" \
     -d '{"bibcodes": ["1999ApJ...517..565P", "2012ApJ...746...85S"], "types": ["basic", "indicators"]}'

Cross-Match with Astronomical Databases

Find papers about a specific object and link to SIMBAD/NED:

curl -H "Authorization: Bearer YOUR_TOKEN" \
     "https://api.adsabs.harvard.edu/v1/search/query?q=object:%22Crab+Nebula%22+AND+year:2024-2026&fl=title,author,year,bibcode,doi&rows=10&sort=date+desc"

References

• Official documentation: https://ui.adsabs.harvard.edu/help/api/
• ADS query syntax: https://ui.adsabs.harvard.edu/help/search/
• ADS search fields: https://ui.adsabs.harvard.edu/help/search/search-syntax