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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. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  2. Fermi GRB 240730B: Global MASTER-Net observations report
  3. GRB 240730B: Fermi GBM Final Real-time Localization
  4. Swift GRB 240730A: Global MASTER-Net observations report
  5. GRB 240730A: Swift-XRT refined Analysis
  6. GRB 240715A: Swift-XRT afterglow detection
  7. GRB 240730A: KAIT Optical Upper Limit
  8. GRB 240727C: GRBAlpha detection
  9. GRB 240730A: Swift/UVOT Upper Limits
  10. GRB 240730A: Enhanced Swift-XRT position
  11. GRB 240730A: Swift detection of a burst
  12. Fermi trigger No 743953682: Global MASTER-Net observations report
  13. GRB 240727A: Swift-BAT refined analysis
  14. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  15. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  16. GRB 240727A: observations of optical counterpart.
  17. GRB 240727B: Swift-XRT observations
  18. Fermi GRB 240727A: Global MASTER-Net observations report
  19. GRB 240727A: Swift/UVOT detection
  20. Fermi trigger No 743868421: Global MASTER-Net observations report
  21. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  22. GRB 240727A: Correction to time in GCN36960
  23. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  24. EP-WXT trigger 01709002661 is not a real source
  25. GRB 240727A: NOT optical observation
  26. GRB 240727A: JinShan optical upper limits
  27. GRB 240727A Bassano Bresciano Observatory upper limit
  28. GRB 240727D: Correction to the GRB name in GCN 36958
  29. GRB 240727A: Fermi GBM Final Real-time Localization
  30. GRB 240727C: AstroSat CZTI detection of a long burst
  31. GRB 240727A: Swift-XRT refined Analysis
  32. GRB 240720B: GRBAlpha detection
  33. GRB 240718A: GRBAlpha detection
  34. GRB 240710B: GRBAlpha detection
  35. GRB 240627A: GRBAlpha detection
  36. Fermi GRB 240726A: Global MASTER-Net observations report
  37. GRB 240727A: Enhanced Swift-XRT position
  38. GRB 240727B: Fermi GBM Observation
  39. Swift GRB240727.16: Global MASTER-Net observations report
  40. GRB240529A: VIRT optical transient detection
  41. GRB 240727B: Swift ToO observations
  42. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  43. GRB 240726A: SVOM/GRM observation
  44. GRB 240727B: AstroSat CZTI detection
  45. GRB 240726B: AstroSat CZTI detection of a short burst
  46. GRB240727A: Skynet Optical Afterglow Observations
  47. GRB 240727A: TRT optical afterglow detection
  48. GRB 240727A: KAIT Optical Afterglow Candidate
  49. GRB 240727A: Swift detection of a burst
  50. GRB 240726A: AstroSat CZTI detection of a short burst
  51. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 240726A: Fermi GBM Final Real-time Localization
  53. Fermi-LAT gamma-ray observations of IceCube-240725A
  54. IceCube Alert 240725.22: Global MASTER-Net observations report
  55. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  56. Swift Trigger 1244778 is not a GRB
  57. Swift GRB240725.11: Global MASTER-Net observations report
  58. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  59. GRB 240720A: Swift-BAT refined analysis
  60. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  61. Fermi trigger No 743418632: Global MASTER-Net observations report
  62. Fermi trigger No 743315411: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  64. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  65. Fermi trigger No 743345551: Global MASTER-Net observations report
  66. Fermi-LAT gamma-ray observations of IceCube-240721A
  67. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  68. Fermi trigger No 743219692: Global MASTER-Net observations report
  69. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  70. IceCube Alert 240721.68: Global MASTER-Net observations report
  71. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  72. GRB 240720B: SVOM/GRM observation
  73. GRB 240721A: Fermi GBM Final Real-time Localization
  74. GRB 240720B: AstroSat CZTI detection of a short burst
  75. Fermi GRB 240720A: Global MASTER-Net observations report
  76. GRB 240720A: AstroSat CZTI detection
  77. GRB 240720A: Fermi GBM observation
  78. GRB 240720A: Swift detection of a burst
  79. Swift GRB240720.02: Global MASTER-Net observations report
  80. Konus-Wind detection of GRB 240718A
  81. GRB 240713A: SVOM/GRM observation
  82. Fermi GRB 240718A: Global MASTER-Net observations report
  83. LAT GRB240718.27: Global MASTER-Net observations report
  84. GRB 240718A: Fermi GBM Observation
  85. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  86. GRB 240718A: Fermi-LAT Detection
  87. GRB 240718A: SVOM/GRM observation
  88. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  89. GRB 240718A: Fermi GBM Final Real-time Localization
  90. GRB 240712A: Swift-BAT refined analysis
  91. GRB 240716A: GECAM-B detection of a long burst
  92. SVOM/GRM In-Flight Trigger of GRB 240716A
  93. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  94. GRB 240713A: 2.2m CAHA optical limit
  95. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  96. GRB 240715A: Swift/UVOT observations of the XRT sources.
  97. GRB 240715A: Swift-XRT observations
  98. GRB240713A: Swift/UVOT Upper LImits
  99. EP240708a: X-ray follow-up observations with Swift/XRT
  100. GRB 240715A: GECAM-C detection of a short burst

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