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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"

28081 results found.

  1. GRB 101011A: Enhanced Swift-XRT position
  2. GRB 101011A: Swift-BAT refined analysis
  3. GRB 101011A: Swift detection of a burst
  4. GRB 101008A: Swift-BAT refined analysis
  5. GRB101008A, GROND detection of a fading afterglow
  6. GRB 101008A: Swift-XRT refined analysis
  7. GRB 101008A: SAO RAS optical observations
  8. GRB 100915 optical upper limit
  9. GRB 101008: Swift/UVOT Upper Limits
  10. GRB 101008A: Enhanced Swift-XRT position
  11. GRB 101008A: Swift/XRT Detection of an Afterglow with no UVOT Counterpart
  12. GRB 101008A: Swift detection of a burst
  13. Refined analysis shows Swift Trigger 435520 is not a GRB
  14. Swift Trigger 435520 is probably not a GRB
  15. GRB 100925A / MAXI J1659-152: MASTER optical observations
  16. GRB 100924A: Suzaku WAM observation of the prompt emission
  17. GRB 100928A, Swift-BAT refined analysis
  18. GRB 100924A: Fermi GBM observation
  19. GRB 100928A: Swift detection of a burst
  20. GRB100925A/MAXI J1659-152 MITSuME Ishigakijima and Okayama Optical Observation
  21. GRB 100925A / MAXI J1659-152: SARA-S Observations
  22. GRB 100925A/MAXI J1659-152: Submm observations from APEX
  23. GRB100925A/MAXI J1659-152: Galactic origin from SED analysis
  24. GRB 100925A/MAXI J1659-152 - NOT optical observations
  25. GRB 100925A / MAXI J1659-152: BOOTES-2/TELMA and IAC80 optical observations
  26. GRB 100925A: Nearby DSS Source - SN-GRB or new Galactic transient?
  27. GRB100925A UVOT afterglow
  28. GRB 100924A: GROND detection of an optical/NIR afterglow
  29. GRB 100925A: Swift detection of a burst
  30. GRB 100924A: Swift-BAT refined analysis
  31. GRB 100917A: TAROT La Silla observatory optical observations
  32. GRB 100915A: TAROT Calern observatory optical observations
  33. GRB100906A: Ashra-1 observation of early optical emission
  34. GRB 100916A: Fermi GBM detection
  35. GRB 100917A: Swift-BAT refined analysis
  36. GRB 100917A: Swift detection of a burst
  37. GRB100915A: MITSuME Ishigakijima Optical upper limits
  38. GRB 100915B: GRT Optical Observation
  39. GRB 100915A: GRT Optical Observation
  40. GRB 100915B: Fermi GBM observation
  41. GRB 100915A: Correction to Swift-BAT refined analysis
  42. GRB 100915A: Swift/UVOT Upper Limits
  43. GRB 100915A: Swift-BAT refined analysis
  44. GRB 100915A: Swift-XRT refined analysis
  45. GRB 100915A: Enhanced Swift-XRT position
  46. GRB 100915B: a long GRB detected by INTEGRAL
  47. GRB 100915A: Swift detection of a likely burst
  48. GRB 100910A: Fermi GBM detection
  49. Swift BAT Trigger 433953 probably not a GRB
  50. GRB100909A: MITSuME Ishigakijima Optical upper limits
  51. GRB 100909A: Swift/UVOT observations
  52. GRB 100901A: errata of GRB name in GCN 11270
  53. GRB 100909A: Swift-XRT refined analysis
  54. GRB 100906A: optical observations at Mt.Terskol
  55. GRB 100901A: optical observation in Maidanak, break confirmation
  56. GRB 100909A: Faulkes Telescope North afterglow candidate
  57. GRB 100902A : Confirmation of afterglow and re-brightening with CFHT r’-band imaging
  58. GRB 100909A: Swift target of opportunity observation
  59. GRB100906A: detection at 15GHz
  60. GRB100901A: IAO optical upper limits at 4 days after the burst
  61. GRB100906A: R band observations
  62. GRB100906A: non-detection at 15GHz
  63. GRB100906A: Optical observations at IAO
  64. GRB 100906A: Fermi GBM observation
  65. GRB 100906A: Swift-XRT refined analysis
  66. GRB 100906A: Enhanced Swift-XRT position
  67. GRB 100906A: Swift/UVOT Observations
  68. GRB100906A: MITSuME Okayama Optical Observation
  69. GRB 100905A: Swift/UVOT Upper Limits
  70. GRB 100901A: TLS observations, SDSS calibration, decay slope
  71. GRB 100906A: MASTER preliminary prompt+afterglow lc
  72. GRB 100906A: Swift-BAT refined analysis
  73. GRB 100906A: Swift detection of a burst with an optical afterglow
  74. GRB 100829A: MASTER optical observations
  75. GRB100905A: Optical upper limits at IAO
  76. GRB100905A: MITSuME Okayama optical upper limits
  77. GRB 100905A: Swift-XRT refined analysis.
  78. GRB100905A: 1.5m OSN upper limit
  79. GRB 100905A: Enhanced Swift-XRT position
  80. GRB 100905A: Swift-BAT refined analysis
  81. GRB 100905A: Faulkes Telescope North observations
  82. GRB 100905A: Swift detection of a burst
  83. GRB10901A: Murikabushi telescope observation at 3 days after the burst
  84. GRB 100901A: Submm observations from SMA
  85. GRB 100904A: Swift-BAT refined analysis
  86. GRB100902A: Optical upper limits at IAO
  87. GRB10901A: Optical observations at IAO
  88. GRB 100902A: Swift-BAT refined analysis
  89. IPN Triangulation of the very bright GRB 100829A
  90. GRB 100902A: Swift XRT refined analysis
  91. GRB 100902A: Swift/UVOT Upper Limits
  92. GRB 100902A: optical observation at Mt.Terskol
  93. GRB 100901A: optical observation at Mt.Terskol
  94. GRB100901A: MITSuME Okayama Optical Observation at 1 day after the burst
  95. GRB 100902A: Enhanced Swift-XRT position
  96. GRB 100901A: TLS Observations: Break?
  97. GRB 100901A: ISON-NM optical observations
  98. GRB 100902A: Faulkes Telescope South observations
  99. GRB 100902A: Swift detection of a burst
  100. GRB 100901A: Vega telescope optical afterglow observation

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