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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 230908A: GRBAlpha detection
  2. LIGO/Virgo/KAGRA S230908b: one counterpart neutrino candidate from IceCube neutrino searches
  3. GRB 230908A: AstroSat CZTI detection
  4. Glowbug gamma-ray detection GRB 230905B
  5. GRB 230906A: Swift/UVOT Upper Limits
  6. GRID detection of GRB 230827A
  7. GRB 230818A: radio observation with the VLA
  8. GRB 230205A: LBT spectroscopy of two host galaxy candidates
  9. GRB 230906A: Swift-XRT observations
  10. Konus-Wind detection of GRB 230906A (short)
  11. IPN triangulation of GRB 230906A (short)
  12. GRB 230906A: Swift ToO observations
  13. GRB 230905B: AstroSat CZTI detection
  14. Fermi GRB 230906A: Global MASTER-Net observations report
  15. Swift Attitude Control Affecting Some UVOT Images
  16. GRB 230812B: Chandra late-time detection of the X-ray afterglow
  17. GRB 230906A: Fermi GBM Final Localizationn
  18. GRB 230905B: GECAM-C detection of a long burst
  19. LIGO/Virgo/KAGRA S230904n: Updated Sky localization and EM Bright Classification
  20. GRB 230905A: Fermi GBM Final Real-time Localization
  21. LIGO/Virgo/KAGRA S230819ax: Correction to PROB_BBH and PROB_TERRES probabilities
  22. GRB 230903A: Swift-XRT refined Analysis
  23. GRB 230903A: Enhanced Swift-XRT position
  24. GRB 230903A: VLT/X-shooter optical observations
  25. GRB 230903A: Swift-BAT refined analysis
  26. GRB 230904C: Fermi GBM Final Localization
  27. Fermi trigger No 715552087: Global MASTER-Net observations report
  28. Fermi trigger No 715429986: Global MASTER-Net observations report
  29. Fermi GRB 230903A: Global MASTER-Net observations report
  30. GRB 230903A: Fermi GBM detection
  31. GRB 230904B is not a GRB
  32. LIGO/Virgo/KAGRA S230904n: 1 counterpart neutrino candidate from IceCube neutrino searches
  33. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  34. Fermi GRB 230904A: Global MASTER-Net observations report
  35. GRB 230904A: Fermi GBM Final Real-time Localization
  36. LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
  37. GRB 230903A: LCOGT Optical Upper Limits
  38. GRB 230903A: Swift detection of a burst
  39. Swift GRB230903.72: Global MASTER-Net observations report
  40. GRB 230903A: Fermi GBM Final Real-time Localization
  41. Integral GRB230902.00: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  43. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  44. GRB 230827B: Glowbug gamma-ray detection
  45. GRB 230827A: Glowbug gamma-ray detection
  46. GRB 230826A: Glowbug gamma-ray detection
  47. GRB 230827B: Swift-XRT afterglow detection
  48. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  51. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  52. GRB 230827B: Swift ToO observations
  53. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  54. GRB 230827A: Fermi GBM Observation
  55. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  56. GRB 230826A: Swift-BAT refined analysis
  57. GRB 230828A: AstroSat CZTI detection
  58. GRB 230828A: GRBAlpha detection
  59. Swift Trigger 1188089 is not a GRB
  60. GRB 230827A: VZLUSAT-2 detection
  61. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  62. GRB 230826A: VZLUSAT-2 detection
  63. GRB 230827B: VZLUSAT-2 detection
  64. GRB 230827B / GRB 230827256: Fermi GBM Observation
  65. GRB 230827A: GRBAlpha detection
  66. Subject: GRB230826A: Swift/UVOT upper limits
  67. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  68. Fermi trigger No 714809315: Global MASTER-Net observations report
  69. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  70. Fermi GRB 230827A: Global MASTER-Net observations report
  71. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  72. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  73. GRB 230827A: Fermi GBM Final Real-time Localization
  74. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  75. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  76. GRB 230826A: GRBAlpha detection
  77. GRB 230826A: Fermi GBM Observation
  78. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  79. GRB 230826A: Enhanced Swift-XRT position
  80. GRB 230826A: Swift-XRT refined Analysis
  81. GRB 230826A: Mondy optical observations
  82. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  83. GRB 230826A: Swift detection of a burst
  84. GRB 230826A: Fermi GBM Final Real-time Localization
  85. Swift GRB230826.81: Global MASTER-Net observations report
  86. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  87. GRB 230824A: AKO Photometric Follow-up Observations
  88. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  89. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  90. Swift GRB230825.85: Global MASTER-Net observations report
  91. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  92. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  93. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  94. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  95. Swift GRB230825.75: Global MASTER-Net observations report
  96. GRB 230812B: radio detection with the VLA
  97. Swift Trigger 1187199 is not an astrophysical event
  98. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  99. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  100. LIGO/Virgo/KAGRA S230825k: Updated Sky localization

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