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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24 results found.

  1. GRB 210919A: Maidanak optical observations
  2. GRB 210919A: SPI-ACS/INTEGRAL observation and evaluation of Ep
  3. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  4. GRB 210919A: FORS2/VLT observations
  5. GRB 210919A: LDT optical observations and candidate host galaxies
  6. GRB 210919A: iTelescope T-11 upper limits
  7. GRB 210919A OSN 1.5m Source Confirmation
  8. GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
  9. GRB 210919A: Chandra rapid ToO upper limit
  10. GRB 210919A: DECam Upper Limits
  11. GRB 210919A: Swift-BAT refined analysis
  12. GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
  13. GRB 210919a: Lowell Discovery Telescope upper limits
  14. GRB 210919A: Swift/UVOT Upper Limits
  15. GRB 210919A: LOAO and LSGT optical upper limits
  16. GRB 210919A: MITSuME Akeno optical upper limits
  17. GRB 210919A: Swift-XRT refined Analysis
  18. GRB 210919A: NOT upper limits
  19. GRB 210919A: AbAO optical upper limit
  20. GRB 210919A: Enhanced Swift-XRT position
  21. GRB 210919A: LCO Optical Upper Limit
  22. GRB 210919A: BOOTES-2/TELMA optical upper limit
  23. Swift GRB 210919A: Global MASTER-Net observations report
  24. GRB 210919A: Swift detection of a short burst

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