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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. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  2. GRB 240801B: AstroSat CZTI detection of a bright long burst
  3. Fermi GRB 240801A: Global MASTER-Net observations report
  4. GRB 240801A: Fermi GBM Final Real-time Localization
  5. GRB 240730C: AstroSat CZTI detection of a long burst
  6. GRB 240731A: Fermi GBM Final Localization
  7. Fermi trigger No 744128417: Global MASTER-Net observations report
  8. Fermi trigger No 744083370: Global MASTER-Net observations report
  9. GRB 240731A: AstroSat CZTI detection
  10. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  11. GRB240730A: BOOTES-5/JGT early optical upper limit
  12. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  13. Fermi GRB 240730B: Global MASTER-Net observations report
  14. GRB 240730B: Fermi GBM Final Real-time Localization
  15. Swift GRB 240730A: Global MASTER-Net observations report
  16. GRB 240730A: Swift-XRT refined Analysis
  17. GRB 240715A: Swift-XRT afterglow detection
  18. GRB 240730A: KAIT Optical Upper Limit
  19. GRB 240727C: GRBAlpha detection
  20. GRB 240730A: Swift/UVOT Upper Limits
  21. GRB 240730A: Enhanced Swift-XRT position
  22. GRB 240730A: Swift detection of a burst
  23. Fermi trigger No 743953682: Global MASTER-Net observations report
  24. GRB 240727A: Swift-BAT refined analysis
  25. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  26. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  27. GRB 240727A: observations of optical counterpart.
  28. GRB 240727B: Swift-XRT observations
  29. Fermi GRB 240727A: Global MASTER-Net observations report
  30. GRB 240727A: Swift/UVOT detection
  31. Fermi trigger No 743868421: Global MASTER-Net observations report
  32. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  33. GRB 240727A: Correction to time in GCN36960
  34. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  35. EP-WXT trigger 01709002661 is not a real source
  36. GRB 240727A: NOT optical observation
  37. GRB 240727A: JinShan optical upper limits
  38. GRB 240727A Bassano Bresciano Observatory upper limit
  39. GRB 240727D: Correction to the GRB name in GCN 36958
  40. GRB 240727A: Fermi GBM Final Real-time Localization
  41. GRB 240727C: AstroSat CZTI detection of a long burst
  42. GRB 240727A: Swift-XRT refined Analysis
  43. GRB 240720B: GRBAlpha detection
  44. GRB 240718A: GRBAlpha detection
  45. GRB 240710B: GRBAlpha detection
  46. GRB 240627A: GRBAlpha detection
  47. Fermi GRB 240726A: Global MASTER-Net observations report
  48. GRB 240727A: Enhanced Swift-XRT position
  49. GRB 240727B: Fermi GBM Observation
  50. Swift GRB240727.16: Global MASTER-Net observations report
  51. GRB240529A: VIRT optical transient detection
  52. GRB 240727B: Swift ToO observations
  53. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  54. GRB 240726A: SVOM/GRM observation
  55. GRB 240727B: AstroSat CZTI detection
  56. GRB 240726B: AstroSat CZTI detection of a short burst
  57. GRB240727A: Skynet Optical Afterglow Observations
  58. GRB 240727A: TRT optical afterglow detection
  59. GRB 240727A: KAIT Optical Afterglow Candidate
  60. GRB 240727A: Swift detection of a burst
  61. GRB 240726A: AstroSat CZTI detection of a short burst
  62. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 240726A: Fermi GBM Final Real-time Localization
  64. Fermi-LAT gamma-ray observations of IceCube-240725A
  65. IceCube Alert 240725.22: Global MASTER-Net observations report
  66. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  67. Swift Trigger 1244778 is not a GRB
  68. Swift GRB240725.11: Global MASTER-Net observations report
  69. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  70. GRB 240720A: Swift-BAT refined analysis
  71. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  72. Fermi trigger No 743418632: Global MASTER-Net observations report
  73. Fermi trigger No 743315411: Global MASTER-Net observations report
  74. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  75. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  76. Fermi trigger No 743345551: Global MASTER-Net observations report
  77. Fermi-LAT gamma-ray observations of IceCube-240721A
  78. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  79. Fermi trigger No 743219692: Global MASTER-Net observations report
  80. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube Alert 240721.68: Global MASTER-Net observations report
  82. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  83. GRB 240720B: SVOM/GRM observation
  84. GRB 240721A: Fermi GBM Final Real-time Localization
  85. GRB 240720B: AstroSat CZTI detection of a short burst
  86. Fermi GRB 240720A: Global MASTER-Net observations report
  87. GRB 240720A: AstroSat CZTI detection
  88. GRB 240720A: Fermi GBM observation
  89. GRB 240720A: Swift detection of a burst
  90. Swift GRB240720.02: Global MASTER-Net observations report
  91. Konus-Wind detection of GRB 240718A
  92. GRB 240713A: SVOM/GRM observation
  93. Fermi GRB 240718A: Global MASTER-Net observations report
  94. LAT GRB240718.27: Global MASTER-Net observations report
  95. GRB 240718A: Fermi GBM Observation
  96. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  97. GRB 240718A: Fermi-LAT Detection
  98. GRB 240718A: SVOM/GRM observation
  99. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  100. GRB 240718A: Fermi GBM Final Real-time Localization

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