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

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