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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"
  1. GRB 230911A: GOTO optical counterpart candidate
  2. GRB 230913A: Fermi GBM Final Real-time Localization
  3. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  4. GRB 230911D: NuSTAR Detection of Prompt Emission
  5. GRB 230911B: AstroSat CZTI detection
  6. GRB 230911C: Swift-XRT refined Analysis
  7. GRB 230911C: Swift-BAT refined analysis
  8. LIGO/Virgo/KAGRA S230911ae: Updated Sky localization
  9. GRB230911C: BOOTES-6/DPRT optical upper limit
  10. GRB 230906A: Chandra detection of the X-ray afterglow
  11. Swift GRB 230911C: Global MASTER-Net observations report
  12. GRB 230911D: Fermi GBM observation
  13. IPN triangulation of GRB 230911D (long)
  14. GRB 230911D: Fermi-LAT detection
  15. GRB230911C: LCOGT Optical Upper Limits
  16. LIGO/Virgo/KAGRA S230911ae: Identification of a GW compact binary merger candidate
  17. GRB 230911C: Swift/UVOT Upper Limits
  18. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
  19. Fermi trigger No 716145795: Global MASTER-Net observations report
  20. GRB 230911C: GOTO optical upper limits
  21. GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  22. GRB 230911B: correction to the KW GCN 34659
  23. Konus-Wind detection of GRB 230811D
  24. GRB 230911C: Enhanced Swift-XRT position
  25. GRB 230911D: BALROG localization (Fermi Trigger 716111594/ GRB 230911329)
  26. GRB 230911D: Fermi GBM Final Localization
  27. GRB 230911C: Swift detection of a burst
  28. Fermi GRB 230911B: Global MASTER-Net observations report
  29. GRB 230911B: Fermi GBM Final Real-time Localization
  30. GRB 230911A: Fermi GBM Final Real-time Localization
  31. GRB 230906A: BlackGEM upper limits
  32. GRB 230903A: TESS observations of optical emission
  33. GRB 230906A: AstroSat CZTI detection
  34. GRB 230910A: Fermi GBM Final Real-time Localization
  35. GRB 230908A: GRBAlpha detection
  36. LIGO/Virgo/KAGRA S230908b: one counterpart neutrino candidate from IceCube neutrino searches
  37. GRB 230908A: AstroSat CZTI detection
  38. Glowbug gamma-ray detection GRB 230905B
  39. GRB 230906A: Swift/UVOT Upper Limits
  40. GRID detection of GRB 230827A
  41. GRB 230818A: radio observation with the VLA
  42. GRB 230205A: LBT spectroscopy of two host galaxy candidates
  43. GRB 230906A: Swift-XRT observations
  44. Konus-Wind detection of GRB 230906A (short)
  45. IPN triangulation of GRB 230906A (short)
  46. GRB 230906A: Swift ToO observations
  47. GRB 230905B: AstroSat CZTI detection
  48. Fermi GRB 230906A: Global MASTER-Net observations report
  49. Swift Attitude Control Affecting Some UVOT Images
  50. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  51. GRB 230906A: Fermi GBM Final Localizationn
  52. GRB 230905B: GECAM-C detection of a long burst
  53. LIGO/Virgo/KAGRA S230904n: Updated Sky localization and EM Bright Classification
  54. GRB 230905A: Fermi GBM Final Real-time Localization
  55. LIGO/Virgo/KAGRA S230819ax: Correction to PROB_BBH and PROB_TERRES probabilities
  56. GRB 230903A: Swift-XRT refined Analysis
  57. GRB 230903A: Enhanced Swift-XRT position
  58. GRB 230903A: VLT/X-shooter optical observations
  59. GRB 230903A: Swift-BAT refined analysis
  60. GRB 230904C: Fermi GBM Final Localization
  61. Fermi trigger No 715552087: Global MASTER-Net observations report
  62. Fermi trigger No 715429986: Global MASTER-Net observations report
  63. Fermi GRB 230903A: Global MASTER-Net observations report
  64. GRB 230903A: Fermi GBM detection
  65. GRB 230904B is not a GRB
  66. LIGO/Virgo/KAGRA S230904n: 1 counterpart neutrino candidate from IceCube neutrino searches
  67. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  68. Fermi GRB 230904A: Global MASTER-Net observations report
  69. GRB 230904A: Fermi GBM Final Real-time Localization
  70. LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
  71. GRB 230903A: LCOGT Optical Upper Limits
  72. GRB 230903A: Swift detection of a burst
  73. Swift GRB230903.72: Global MASTER-Net observations report
  74. GRB 230903A: Fermi GBM Final Real-time Localization
  75. Integral GRB230902.00: Global MASTER-Net observations report
  76. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  77. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  78. GRB 230827B: Glowbug gamma-ray detection
  79. GRB 230827A: Glowbug gamma-ray detection
  80. GRB 230826A: Glowbug gamma-ray detection
  81. GRB 230827B: Swift-XRT afterglow detection
  82. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  85. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  86. GRB 230827B: Swift ToO observations
  87. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  88. GRB 230827A: Fermi GBM Observation
  89. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  90. GRB 230826A: Swift-BAT refined analysis
  91. GRB 230828A: AstroSat CZTI detection
  92. GRB 230828A: GRBAlpha detection
  93. Swift Trigger 1188089 is not a GRB
  94. GRB 230827A: VZLUSAT-2 detection
  95. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  96. GRB 230826A: VZLUSAT-2 detection
  97. GRB 230827B: VZLUSAT-2 detection
  98. GRB 230827B / GRB 230827256: Fermi GBM Observation
  99. GRB 230827A: GRBAlpha detection
  100. Subject: GRB230826A: Swift/UVOT upper limits

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