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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. Swift GRB 230911C: Global MASTER-Net observations report
  2. GRB 230911D: Fermi GBM observation
  3. IPN triangulation of GRB 230911D (long)
  4. GRB 230911D: Fermi-LAT detection
  5. GRB230911C: LCOGT Optical Upper Limits
  6. LIGO/Virgo/KAGRA S230911ae: Identification of a GW compact binary merger candidate
  7. GRB 230911C: Swift/UVOT Upper Limits
  8. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
  9. Fermi trigger No 716145795: Global MASTER-Net observations report
  10. GRB 230911C: GOTO optical upper limits
  11. GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  12. GRB 230911B: correction to the KW GCN 34659
  13. Konus-Wind detection of GRB 230811D
  14. GRB 230911C: Enhanced Swift-XRT position
  15. GRB 230911D: BALROG localization (Fermi Trigger 716111594/ GRB 230911329)
  16. GRB 230911D: Fermi GBM Final Localization
  17. GRB 230911C: Swift detection of a burst
  18. Fermi GRB 230911B: Global MASTER-Net observations report
  19. GRB 230911B: Fermi GBM Final Real-time Localization
  20. GRB 230911A: Fermi GBM Final Real-time Localization
  21. GRB 230906A: BlackGEM upper limits
  22. GRB 230903A: TESS observations of optical emission
  23. GRB 230906A: AstroSat CZTI detection
  24. GRB 230910A: Fermi GBM Final Real-time Localization
  25. GRB 230908A: GRBAlpha detection
  26. LIGO/Virgo/KAGRA S230908b: one counterpart neutrino candidate from IceCube neutrino searches
  27. GRB 230908A: AstroSat CZTI detection
  28. Glowbug gamma-ray detection GRB 230905B
  29. GRB 230906A: Swift/UVOT Upper Limits
  30. GRID detection of GRB 230827A
  31. GRB 230818A: radio observation with the VLA
  32. GRB 230205A: LBT spectroscopy of two host galaxy candidates
  33. GRB 230906A: Swift-XRT observations
  34. Konus-Wind detection of GRB 230906A (short)
  35. IPN triangulation of GRB 230906A (short)
  36. GRB 230906A: Swift ToO observations
  37. GRB 230905B: AstroSat CZTI detection
  38. Fermi GRB 230906A: Global MASTER-Net observations report
  39. Swift Attitude Control Affecting Some UVOT Images
  40. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  41. GRB 230906A: Fermi GBM Final Localizationn
  42. GRB 230905B: GECAM-C detection of a long burst
  43. LIGO/Virgo/KAGRA S230904n: Updated Sky localization and EM Bright Classification
  44. GRB 230905A: Fermi GBM Final Real-time Localization
  45. LIGO/Virgo/KAGRA S230819ax: Correction to PROB_BBH and PROB_TERRES probabilities
  46. GRB 230903A: Swift-XRT refined Analysis
  47. GRB 230903A: Enhanced Swift-XRT position
  48. GRB 230903A: VLT/X-shooter optical observations
  49. GRB 230903A: Swift-BAT refined analysis
  50. GRB 230904C: Fermi GBM Final Localization
  51. Fermi trigger No 715552087: Global MASTER-Net observations report
  52. Fermi trigger No 715429986: Global MASTER-Net observations report
  53. Fermi GRB 230903A: Global MASTER-Net observations report
  54. GRB 230903A: Fermi GBM detection
  55. GRB 230904B is not a GRB
  56. LIGO/Virgo/KAGRA S230904n: 1 counterpart neutrino candidate from IceCube neutrino searches
  57. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  58. Fermi GRB 230904A: Global MASTER-Net observations report
  59. GRB 230904A: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
  61. GRB 230903A: LCOGT Optical Upper Limits
  62. GRB 230903A: Swift detection of a burst
  63. Swift GRB230903.72: Global MASTER-Net observations report
  64. GRB 230903A: Fermi GBM Final Real-time Localization
  65. Integral GRB230902.00: Global MASTER-Net observations report
  66. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  67. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  68. GRB 230827B: Glowbug gamma-ray detection
  69. GRB 230827A: Glowbug gamma-ray detection
  70. GRB 230826A: Glowbug gamma-ray detection
  71. GRB 230827B: Swift-XRT afterglow detection
  72. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  75. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  76. GRB 230827B: Swift ToO observations
  77. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  78. GRB 230827A: Fermi GBM Observation
  79. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  80. GRB 230826A: Swift-BAT refined analysis
  81. GRB 230828A: AstroSat CZTI detection
  82. GRB 230828A: GRBAlpha detection
  83. Swift Trigger 1188089 is not a GRB
  84. GRB 230827A: VZLUSAT-2 detection
  85. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  86. GRB 230826A: VZLUSAT-2 detection
  87. GRB 230827B: VZLUSAT-2 detection
  88. GRB 230827B / GRB 230827256: Fermi GBM Observation
  89. GRB 230827A: GRBAlpha detection
  90. Subject: GRB230826A: Swift/UVOT upper limits
  91. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  92. Fermi trigger No 714809315: Global MASTER-Net observations report
  93. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  94. Fermi GRB 230827A: Global MASTER-Net observations report
  95. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  96. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  97. GRB 230827A: Fermi GBM Final Real-time Localization
  98. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  99. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  100. GRB 230826A: GRBAlpha detection

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