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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 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
  2. IPN triangulation of GRB 230919A (short)
  3. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  4. GRB 230919A: Fermi GBM Observation
  5. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  6. Fermi GBM Statement for Trigger 716527670/230916144
  7. GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
  8. LIGO/Virgo/KAGRA S230920al: Updated Sky localization
  9. LIGO/Virgo/KAGRA S230919bj: Updated Sky localization
  10. transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
  11. GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
  12. GRB 230919A: AstroSat CZTI detection
  13. LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
  14. AT2023sva: redshift from OSIRIS+/GTC of the ZTF afterglow
  15. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  16. GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
  17. GRB 230919A: Fermi GBM Final Real-time Localization
  18. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  19. Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
  20. GRB 230918B: Fermi GBM Final Real-time Localization
  21. GRB 230918A (short): Glowbug gamma-ray detection
  22. GRB 230916B: Glowbug gamma-ray detection
  23. AT 2023sva: NOT observations of the ZTF candidate afterglow
  24. ZTF and SEDM Observations of the Candidate Optical Afterglow AT 2023sva
  25. GRB 230915A: Fermi GBM observation
  26. LIGO/Virgo/KAGRA S230918aq: Retraction of GW compact binary merger candidate
  27. GRB 230812B: Radio observations with the uGMRT
  28. GRB 230918A: Fermi GBM Final Real-time Localization
  29. GRB 230917A: AstroSat CZTI detection
  30. Swift Triggers 1192480, 1192481, 1192482 and 1192483 are not astrophysical events
  31. LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
  32. GRB 230915B: Glowbug gamma-ray detection
  33. GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
  34. GRB 230911A: Fermi GBM Observation
  35. Swift GRB230916.18: Global MASTER-Net observations report
  36. Fermi trigger No 716572242: Global MASTER-Net observations report
  37. LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
  38. Fermi trigger No 716544961: Global MASTER-Net observations report
  39. Fermi-LAT gamma-ray observations of IceCube-230914A
  40. GRB 230915A: Swift/BAT-GUANO detection of a burst
  41. LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
  42. GRB 230911D: GRBAlpha detection
  43. Swift GRB230916.19: Global MASTER-Net observations report
  44. Swift GRB230916.18: Global MASTER-Net observations report
  45. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  46. Swift GRB230916.13: Global MASTER-Net observations report
  47. Swift GRB230916.12: Global MASTER-Net observations report
  48. Swift GRB230916.11: Global MASTER-Net observations report
  49. Swift Trigger 1192233 is not a GRB
  50. GRB 230906A: optical counterpart
  51. IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 230911A: Swift-XRT afterglow detection
  53. Fermi trigger No 716449174: Global MASTER-Net observations report
  54. GRB 230913A: CALET Gamma-Ray Burst Monitor detection
  55. IceCube Alert 230914.22: Global MASTER-Net observations report
  56. Swift Trigger 1192088 is not an astrophysical event
  57. Fermi trigger No 716419312: Global MASTER-Net observations report
  58. GRB 230913A: Glowbug gamma-ray detection
  59. LIGO/Virgo/KAGRA S230914ak: Updated Sky localization
  60. GRB 230812B: Bad Time Intervals for Fermi GBM data
  61. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  62. LIGO/Virgo/KAGRA S230914ak: Identification of a GW compact binary merger candidate
  63. Swift Trigger 1191994 is not an astrophysical event
  64. Swift GRB230913.70: Global MASTER-Net observations report
  65. GRB 230913A: Fermi GBM Observation
  66. LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
  67. Swift Trigger 1191904 is not a GRB
  68. Swift GRB230913.70: Global MASTER-Net observations report
  69. Swift Trigger 1191903 is not an astrophysical event
  70. GRB 230911A: Swift ToO observations
  71. GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
  72. Fermi GRB 230913A: Global MASTER-Net observations report
  73. GRB 230911A: GOTO optical counterpart candidate
  74. GRB 230913A: Fermi GBM Final Real-time Localization
  75. GRB 230908A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 230911D: NuSTAR Detection of Prompt Emission
  77. GRB 230911B: AstroSat CZTI detection
  78. GRB 230911C: Swift-XRT refined Analysis
  79. GRB 230911C: Swift-BAT refined analysis
  80. LIGO/Virgo/KAGRA S230911ae: Updated Sky localization
  81. GRB230911C: BOOTES-6/DPRT optical upper limit
  82. GRB 230906A: Chandra detection of the X-ray afterglow
  83. Swift GRB 230911C: Global MASTER-Net observations report
  84. GRB 230911D: Fermi GBM observation
  85. IPN triangulation of GRB 230911D (long)
  86. GRB 230911D: Fermi-LAT detection
  87. GRB230911C: LCOGT Optical Upper Limits
  88. LIGO/Virgo/KAGRA S230911ae: Identification of a GW compact binary merger candidate
  89. GRB 230911C: Swift/UVOT Upper Limits
  90. GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
  91. Fermi trigger No 716145795: Global MASTER-Net observations report
  92. GRB 230911C: GOTO optical upper limits
  93. GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  94. GRB 230911B: correction to the KW GCN 34659
  95. Konus-Wind detection of GRB 230811D
  96. GRB 230911C: Enhanced Swift-XRT position
  97. GRB 230911D: BALROG localization (Fermi Trigger 716111594/ GRB 230911329)
  98. GRB 230911D: Fermi GBM Final Localization
  99. GRB 230911C: Swift detection of a burst
  100. Fermi GRB 230911B: Global MASTER-Net observations report

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