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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"

5039 results found.

  1. GRB 210413B: MITSuME Okayama optical upper limits
  2. GRB 210419C: MITSuME Akeno optical upper limits
  3. GRB 210419A: Swift-XRT refined Analysis
  4. GRB 210410A: MITSuME Akeno optical upper limits
  5. Fermi GRB 210411A: Global MASTER-Net observations report
  6. GRB 210402A: Swift-XRT refined Analysis
  7. GRB 210324A: AstroSat CZTI detection
  8. GRB 210324C: AstroSat CZTI detection
  9. GRB 210323A: MASTER optical observation
  10. Fermi GRB 210324C: Global MASTER-Net observations report
  11. Fermi GRB 210324B: Global MASTER-Net observations report
  12. GRB 210324C: BALROG localization (Fermi Trigger 638308803 / GRB 210324833)
  13. GRB 210324C: Fermi GBM Final Real-time Localization
  14. GRB 210324B: Fermi GBM Final Real-time Localization
  15. GRB 210324A: Fermi GBM Final Real-time Localization
  16. GRB 210323A: Swift-XRT refined Analysis
  17. Swift GRB 210323A: Global MASTER-Net observations report
  18. GRB 210321A: Swift-XRT refined Analysis
  19. GRB 210318B: MITSuME Okayama optical upper limits
  20. GRB210318B: Swift detection of a burst
  21. Fermi trigger No 637521056: Global MASTER-Net observations report
  22. Fermi GRB 210312A: Global MASTER-Net observations report
  23. GRB 210308A: MITSuME Okayama optical upper limits
  24. GRB 210306A: continued Mondy optical observations
  25. GRB 210308A: Swift detection of a burst with an optical counterpart
  26. GRB 210306A: MITSuME Akeno optical observation
  27. GRB 210306A: iTelescope T24 optical observations
  28. GRB 210305A: Swift detection of a burst
  29. Fermi trigger No 636459103: Global MASTER-Net observations report
  30. GRB 210226A: Swift-XRT refined Analysis
  31. GRB 210222B: MITSuME Akeno optical upper limits
  32. GRB 210222B: Swift-XRT refined Analysis
  33. GRB 210222B: GOTO confirmation of afterglow detection
  34. uGMRT radio detection of GRB 210204A
  35. GRB 210218A: MITSuME Akeno optical upper limits
  36. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  37. ZTF21aakruew/AT2021cwd: ZTF and LT discovery of a hostless, red, and rapidly fading optical transient
  38. GRB 210212A: MITSuME Akeno optical upper limits
  39. GRB 210212A: Swift-XRT refined Analysis
  40. GRB 210211A: Swift-XRT refined Analysis
  41. GRB 210209A: MITSuME Akeno optical upper limits
  42. GRB 210210A: Swift-XRT refined Analysis
  43. GRB 210209A: Swift-XRT refined Analysis
  44. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  45. Swift GRB 210210A: Global MASTER-Net observations report
  46. GRB 210207B: Continued LCO Observations
  47. GRB 210207B: Swift-XRT refined Analysis
  48. Fermi GRB 210207A: Global MASTER-Net observations report
  49. Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
  50. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  51. GRB 210205A: Swift-XRT refined Analysis
  52. ZTF21aagwbjr/AT2021buv: ZTF discovery of a fast optical transient likely associated with GRB 210104A
  53. Fermi GRB 210204B: Global MASTER-Net observations report
  54. GRB 210124B: AstroSat CZTI detection
  55. HAWC Transient event on 2021/01/25
  56. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  57. IPN triangulation of GRB 210121A
  58. Fermi GRB 210119A: Global MASTER-Net observations report
  59. Fermi trigger No 632573937: Global MASTER-Net observations report
  60. GRB 201221D: near-infrared observation with LBT
  61. ZTF21aaeyldq: NOT optical observations
  62. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  63. GRB 210112A: Swift-XRT refined Analysis
  64. GRB 210104A: Swift-XRT refined Analysis
  65. Konus-Wind detection of GRB 210104A
  66. GRB 210104B: Swift-XRT refined Analysis
  67. GRB 210104B: BOOTES network optical upper limit
  68. GRB 210104A: MITSuME Akeno optical observation
  69. Fermi GRB 210102C: Global MASTER-Net observations report
  70. Fermi trigger No 631119348: Global MASTER-Net observations report
  71. Fermi trigger No 631104264: Global MASTER-Net observations report
  72. GRB 201229A: Swift-XRT refined Analysis
  73. ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
  74. Fermi trigger No 630681391: Global MASTER-Net observations report
  75. Baksan Neutrino Observatory Alert 201225.54: Global MASTER-Net observations report
  76. GRB 201223A: Swift-XRT refined Analysis
  77. GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
  78. Baksan Neutrino Observatory Alert 201223.60: Global MASTER-Net observations report
  79. Swift-XRT observations of Icecube 201222A
  80. Fermi trigger No 630389391: Global MASTER-Net observations report
  81. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  82. GRB 201221D: candidate optical counterpart from the NOT
  83. GRB 201221A: Swift-BAT refined analysis
  84. GRB 201221D: Prompt enhanced Swift-XRT position
  85. GRB 201221A: Swift-XRT refined Analysis
  86. Swift Trigger 1014012: possible GRB 201221C
  87. GRB 201221A: Enhanced Swift-XRT position
  88. GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
  89. GRB 201221A: Prompt enhanced Swift-XRT position
  90. GRB 201221A: Swift detection of a burst
  91. Konus-Wind observation of GRB 201218A
  92. Fermi GRB 201218B: Global MASTER-Net observations report
  93. Baksan Neutrino Observatory Alert 201216.94: Global MASTER-Net observations report
  94. Fermi GRB 201216A: Global MASTER-Net observations report
  95. GRB 201208A: Fermi GBM observation
  96. GRB 201207A: AstroSat CZTI detection
  97. Fermi GRB 201208A: Global MASTER-Net observations report
  98. Swift follow-up observations of the flat spectrum radio quasar PMN J0206-1150 in the error region of IceCube-201130A
  99. GRB 201203A: Swift-XRT afterglow detection
  100. IceCube Alert 201130.85: Global MASTER-Net observations report

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