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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"

68 results found.

  1. Fermi GRB 260223A: Global MASTER-Net observations report
  2. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  3. Swift trigger on the HMXB 1A 1118-61
  4. Swift triggered on the HMXB 1A 1118-61
  5. Fermi GRB 260111A: Global MASTER-Net observations report
  6. Fermi GRB 251214A: Global MASTER-Net observations report
  7. EP250905b: Global MASTER-Net observations report
  8. GRB 250819A: AstroSat CZTI detection
  9. GRB 250702A: Fermi GBM Detection
  10. GRB 250507B: AstroSat CZTI detection
  11. EP250407a: Global MASTER-Net observations report
  12. Fermi GRB 250210A: Global MASTER-Net observations report
  13. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  14. GRB 250101A: SVOM/C-GFT early optical observations
  15. Fermi trigger No 751861204: Global MASTER-Net observations report
  16. Fermi trigger No 751554401: Global MASTER-Net observations report
  17. GRB 241001A: Swift-XRT observations
  18. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  19. GRB 240726B: AstroSat CZTI detection of a short burst
  20. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  21. GRB 240225B: Glowbug gamma-ray detection
  22. Fermi GRB 230818A: Global MASTER-Net observations report
  23. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  24. GRB 221006A: Swift-XRT observations
  25. Fermi GRB 220523A: Global MASTER-Net observations report
  26. GRB 220408A: Swift/UVOT Detection
  27. Konus-Wind detection of GRB 220124A
  28. GRB 220117B: Swift/UVOT Upper Limits
  29. Fermi GRB 211031A: Global MASTER-Net observations report
  30. GRB 210926A: AstroSat CZTI detection
  31. Fermi trigger No 647271699: Global MASTER-Net observations report
  32. Integral GRB210707.02: Global MASTER-Net observations report
  33. GRB 210330A: AstroSat CZTI detection
  34. GRB 210307A: Swift-BAT refined analysis
  35. GRB 210212A: Swift/UVOT Upper Limits
  36. GRB 201229A: Swift-XRT refined Analysis
  37. Trigger 1007266: Swift detection of 1A 0535+262
  38. Swift Trigger 1006917 is Be/X-ray binary pulsar 1A 0535+262
  39. GRB 200917A: Swift/UVOT Upper Limits
  40. Fermi GRB 200524A: Global MASTER-Net observations report
  41. GRB 200205A: MAXI/GSC detection
  42. GRB 200109A: Swift-XRT refined Analysis
  43. GRB 190919B: Swift/UVOT Upper Limits
  44. GRB 190519A: Swift/UVOT Upper Limits
  45. GRB 180705A: Swift-BAT refined analysis
  46. GRB 180418A: TAROT La Silla observatory early optical observations
  47. Konus-Wind observation of GRB 171227A
  48. GRB 170808B: Fermi GBM observation
  49. GRB 170419B, Swift-BAT refined analysis
  50. Konus-Wind observation of GRB 151229B
  51. GRB 140626A: Swift/UVOT Upper Limits
  52. GRB 130418A: Swift-XRT refined Analysis
  53. GRB 120624B: Further analysis of the HAWKI observations
  54. GRB 120422A: A Swift/UVOT Detection
  55. IPN Triangulation of GRB 120323A (short/very intense)
  56. IBAS trigger n. 6138 is not a GRB
  57. Swift detection of outburst from the SFXT IGR J18410-0535
  58. GRB100219A Akeno and Okayama MITSuME Optical Observation
  59. GRB 091221: Fermi GBM Observation
  60. GRB 091221: Swift detection of a burst
  61. Konus-Wind observation of bright short GRB 090227B
  62. GRB 090113: Swift detection of a burst
  63. Swift triggered on the HMXB 1A 1118-61
  64. GRB 080325: Swift/UVOT Upper Limits
  65. VLT/UVES redshift of GRB 080319B from FeII fine-structure lines
  66. GRB 071003: Keck HIRES spectroscopy
  67. GRB 070306 Swift/UVOT refined analysis
  68. GRB 050509B: Swift/XRT refined analysis

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