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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo S230531f: Global MASTER-Net observations report
  3. GRB 230525A: CALET Gamma-Ray Burst Monitor detection
  4. LIGO/Virgo/KAGRA S230529ay: Zwicky Transient Facility observations
  5. LIGO/Virgo/KAGRA S230528a: Zwicky Transient Facility observations
  6. LIGO/Virgo/KAGRA S230527ch: Zwicky Transient Facility observations
  7. LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations.
  8. LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
  9. LIGO/Virgo S230529ay: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
  11. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  12. LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
  13. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  14. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  15. LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo S230529p: Global MASTER-Net observations report
  17. GRB 230529A: Fermi GBM Final Real-time Localization
  18. Alert from the HAWC Burst Monitor HAWC-230527A
  19. LIGO/Virgo S230525a: Global MASTER-Net observations report
  20. LIGO/Virgo/KAGRA S230518h: Updated Sky localization
  21. LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
  22. Fermi-LAT gamma-ray observations of IceCube-230524A
  23. LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
  24. GRB 230510A: Swift-BAT refined analysis
  25. GRB 230525A: Fermi GBM Detection
  26. LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
  27. GRB 230525A: Fermi GBM Final Localization
  28. IceCube-230524A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 230523B: GRBAlpha detection
  30. GRB 230524A: Fermi GBM Observation
  31. IceCube Alert 230524.47: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S230518h: No transient candidates in CALET observations
  33. LIGO/Virgo/KAGRA S230524x: Retraction of GW compact binary merger candidate
  34. IceCube-230524A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 230524B: AstroSat CZTI detection
  36. GRB 230524A: AstroSat CZTI detection
  37. GRB 230524A: AGILE detection
  38. Fermi trigger No 706610076: Global MASTER-Net observations report
  39. LIGO/Virgo S230524b: Global MASTER-Net observations report
  40. GRB 230524A: Fermi GBM Final Real-time Localization
  41. Fermi trigger No 706599831: Global MASTER-Net observations report
  42. Fermi trigger No 706536788: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
  44. GRB 230523B: Name correction from GCN Circular 33859
  45. GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
  46. LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
  47. Fermi Gamma-ray Burst Monitor trigger 706536788/230523509 is not a GRB
  48. GRB 230523A: Fermi GBM Final Real-time Localization
  49. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230523A
  50. LIGO/Virgo S230522n: Global MASTER-Net observations report
  51. LIGO/Virgo S230522a: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
  53. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
  54. LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
  55. LIGO/Virgo S230521k: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S230521k: Zwicky Transient Facility observations
  57. GRB 230518B: VZLUSAT-2 detection
  58. Fermi Gamma-ray Burst Monitor trigger 706338208/230521211 is not a GRB
  59. LIGO/Virgo S230520ae: Global MASTER-Net observations report
  60. Fermi trigger No 706328428: Global MASTER-Net observations report
  61. IPN triangulation of GRB 230518A (short)
  62. Fermi trigger No 706331483: Global MASTER-Net observations report
  63. Fermi trigger No 706317104: Global MASTER-Net observations report
  64. GRB 230520A: CALET Gamma-Ray Burst Monitor detection
  65. GRB 230521A: Fermi GBM Final Real-time Localization
  66. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  67. GRB 230520B is not a GRB
  68. GRB 230520B: Fermi GBM Final Real-time Localization
  69. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  70. LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
  71. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  72. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
  73. GRB 230520A: MAXI/GSC detection
  74. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  75. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  76. GRB 230518A: Fermi GBM Observation
  77. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  78. LIGO/Virgo S230518h: AGILE/MCAL observations
  79. GRB 230518A: Swift/BAT-GUANO detection
  80. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  81. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  82. GRB 230518A: Fermi GBM Final Real-time Localization
  83. Fermi Gamma-ray Burst Monitor trigger 706068974/230518095 is not a GRB
  84. LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
  85. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  86. LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
  87. LIGO/Virgo S230518h: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  89. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  90. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  91. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  92. GRB 230513A: Zwicky Transient Facility continuous observations of a Fermi Short GRB (Trigger 705709044)
  93. GRB 230510B: GRBAlpha detection
  94. Fermi trigger No 706014351: Global MASTER-Net observations report
  95. GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
  96. Improved IPN triangulation of GRB 230512A
  97. GRB 230517A: Fermi GBM Final Real-time Localization
  98. GRB 230510B: Fermi GBM detection
  99. Fermi trigger No 705952199: Global MASTER-Net observations report
  100. GRB 230516A: Fermi GBM Final Real-time Localization

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