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

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