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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 240730C: AstroSat CZTI detection of a long burst
  2. GRB 240731A: Fermi GBM Final Localization
  3. Fermi trigger No 744128417: Global MASTER-Net observations report
  4. Fermi trigger No 744083370: Global MASTER-Net observations report
  5. GRB 240731A: AstroSat CZTI detection
  6. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  7. GRB240730A: BOOTES-5/JGT early optical upper limit
  8. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  9. Fermi GRB 240730B: Global MASTER-Net observations report
  10. GRB 240730B: Fermi GBM Final Real-time Localization
  11. Swift GRB 240730A: Global MASTER-Net observations report
  12. GRB 240730A: Swift-XRT refined Analysis
  13. GRB 240715A: Swift-XRT afterglow detection
  14. GRB 240730A: KAIT Optical Upper Limit
  15. GRB 240727C: GRBAlpha detection
  16. GRB 240730A: Swift/UVOT Upper Limits
  17. GRB 240730A: Enhanced Swift-XRT position
  18. GRB 240730A: Swift detection of a burst
  19. Fermi trigger No 743953682: Global MASTER-Net observations report
  20. GRB 240727A: Swift-BAT refined analysis
  21. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  22. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  23. GRB 240727A: observations of optical counterpart.
  24. GRB 240727B: Swift-XRT observations
  25. Fermi GRB 240727A: Global MASTER-Net observations report
  26. GRB 240727A: Swift/UVOT detection
  27. Fermi trigger No 743868421: Global MASTER-Net observations report
  28. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  29. GRB 240727A: Correction to time in GCN36960
  30. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  31. EP-WXT trigger 01709002661 is not a real source
  32. GRB 240727A: NOT optical observation
  33. GRB 240727A: JinShan optical upper limits
  34. GRB 240727A Bassano Bresciano Observatory upper limit
  35. GRB 240727D: Correction to the GRB name in GCN 36958
  36. GRB 240727A: Fermi GBM Final Real-time Localization
  37. GRB 240727C: AstroSat CZTI detection of a long burst
  38. GRB 240727A: Swift-XRT refined Analysis
  39. GRB 240720B: GRBAlpha detection
  40. GRB 240718A: GRBAlpha detection
  41. GRB 240710B: GRBAlpha detection
  42. GRB 240627A: GRBAlpha detection
  43. Fermi GRB 240726A: Global MASTER-Net observations report
  44. GRB 240727A: Enhanced Swift-XRT position
  45. GRB 240727B: Fermi GBM Observation
  46. Swift GRB240727.16: Global MASTER-Net observations report
  47. GRB240529A: VIRT optical transient detection
  48. GRB 240727B: Swift ToO observations
  49. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  50. GRB 240726A: SVOM/GRM observation
  51. GRB 240727B: AstroSat CZTI detection
  52. GRB 240726B: AstroSat CZTI detection of a short burst
  53. GRB240727A: Skynet Optical Afterglow Observations
  54. GRB 240727A: TRT optical afterglow detection
  55. GRB 240727A: KAIT Optical Afterglow Candidate
  56. GRB 240727A: Swift detection of a burst
  57. GRB 240726A: AstroSat CZTI detection of a short burst
  58. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 240726A: Fermi GBM Final Real-time Localization
  60. Fermi-LAT gamma-ray observations of IceCube-240725A
  61. IceCube Alert 240725.22: Global MASTER-Net observations report
  62. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  63. Swift Trigger 1244778 is not a GRB
  64. Swift GRB240725.11: Global MASTER-Net observations report
  65. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  66. GRB 240720A: Swift-BAT refined analysis
  67. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  68. Fermi trigger No 743418632: Global MASTER-Net observations report
  69. Fermi trigger No 743315411: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  71. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  72. Fermi trigger No 743345551: Global MASTER-Net observations report
  73. Fermi-LAT gamma-ray observations of IceCube-240721A
  74. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  75. Fermi trigger No 743219692: Global MASTER-Net observations report
  76. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  77. IceCube Alert 240721.68: Global MASTER-Net observations report
  78. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  79. GRB 240720B: SVOM/GRM observation
  80. GRB 240721A: Fermi GBM Final Real-time Localization
  81. GRB 240720B: AstroSat CZTI detection of a short burst
  82. Fermi GRB 240720A: Global MASTER-Net observations report
  83. GRB 240720A: AstroSat CZTI detection
  84. GRB 240720A: Fermi GBM observation
  85. GRB 240720A: Swift detection of a burst
  86. Swift GRB240720.02: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 240718A
  88. GRB 240713A: SVOM/GRM observation
  89. Fermi GRB 240718A: Global MASTER-Net observations report
  90. LAT GRB240718.27: Global MASTER-Net observations report
  91. GRB 240718A: Fermi GBM Observation
  92. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  93. GRB 240718A: Fermi-LAT Detection
  94. GRB 240718A: SVOM/GRM observation
  95. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  96. GRB 240718A: Fermi GBM Final Real-time Localization
  97. GRB 240712A: Swift-BAT refined analysis
  98. GRB 240716A: GECAM-B detection of a long burst
  99. SVOM/GRM In-Flight Trigger of GRB 240716A
  100. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT

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