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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"

27774 results found.

  1. EP240804a: LCOGT optical counterpart detection
  2. GRB 240805A: A long GRB detected by INTEGRAL
  3. EP240804a: NOT optical counterpart detection
  4. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  5. GRB 240805A: Swift detection of a burst
  6. GRB 240805A: Fermi GBM Final Real-time Localization
  7. GRB 240804A: Fermi GBM Final Real-time Localization
  8. IPN triangulation of GRB 240802A / EP 240802a
  9. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  10. GRB 240802A: AstroSat CZTI detection of a long burst
  11. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  12. GRB 240730A: Swift-BAT refined analysis
  13. EP240801a: GSP follow-up observations of the candidate counterpart
  14. EP240801a: TRT optical counterpart detection
  15. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  16. GRB 240801B: AstroSat CZTI detection of a bright long burst
  17. GRB 240801A: Fermi GBM Final Real-time Localization
  18. GRB 240730C: AstroSat CZTI detection of a long burst
  19. GRB 240731A: Fermi GBM Final Localization
  20. GRB 240731A: AstroSat CZTI detection
  21. GRB240730A: BOOTES-5/JGT early optical upper limit
  22. GRB 240730B: Fermi GBM Final Real-time Localization
  23. Swift GRB 240730A: Global MASTER-Net observations report
  24. GRB 240730A: Swift-XRT refined Analysis
  25. GRB 240715A: Swift-XRT afterglow detection
  26. GRB 240730A: KAIT Optical Upper Limit
  27. GRB 240727C: GRBAlpha detection
  28. GRB 240730A: Swift/UVOT Upper Limits
  29. GRB 240730A: Enhanced Swift-XRT position
  30. GRB 240730A: Swift detection of a burst
  31. GRB 240727A: Swift-BAT refined analysis
  32. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  33. GRB 240727A: observations of optical counterpart.
  34. GRB 240727B: Swift-XRT observations
  35. GRB 240727A: Swift/UVOT detection
  36. GRB 240727A: NOT optical observation
  37. GRB 240727A: JinShan optical upper limits
  38. GRB 240727A Bassano Bresciano Observatory upper limit
  39. GRB 240727A: Fermi GBM Final Real-time Localization
  40. GRB 240727C: AstroSat CZTI detection of a long burst
  41. GRB 240727A: Swift-XRT refined Analysis
  42. GRB 240720B: GRBAlpha detection
  43. GRB 240718A: GRBAlpha detection
  44. GRB 240710B: GRBAlpha detection
  45. GRB 240627A: GRBAlpha detection
  46. GRB 240727A: Enhanced Swift-XRT position
  47. GRB 240727B: Fermi GBM Observation
  48. Swift GRB240727.16: Global MASTER-Net observations report
  49. GRB240529A: VIRT optical transient detection
  50. GRB 240727B: Swift ToO observations
  51. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  52. GRB 240727B: AstroSat CZTI detection
  53. GRB 240726B: AstroSat CZTI detection of a short burst
  54. GRB240727A: Skynet Optical Afterglow Observations
  55. GRB 240727A: TRT optical afterglow detection
  56. GRB 240727A: KAIT Optical Afterglow Candidate
  57. GRB 240727A: Swift detection of a burst
  58. GRB 240726A: AstroSat CZTI detection of a short burst
  59. GRB 240726A: Fermi GBM Final Real-time Localization
  60. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  61. Swift Trigger 1244778 is not a GRB
  62. Swift GRB240725.11: Global MASTER-Net observations report
  63. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  64. GRB 240720A: Swift-BAT refined analysis
  65. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  66. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  67. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 240721A: Fermi GBM Final Real-time Localization
  69. GRB 240720B: AstroSat CZTI detection of a short burst
  70. GRB 240720A: AstroSat CZTI detection
  71. GRB 240720A: Fermi GBM observation
  72. GRB 240720A: Swift detection of a burst
  73. Swift GRB240720.02: Global MASTER-Net observations report
  74. Konus-Wind detection of GRB 240718A
  75. GRB 240718A: Fermi-LAT Detection
  76. GRB 240718A: Fermi GBM Final Real-time Localization
  77. GRB 240712A: Swift-BAT refined analysis
  78. GRB 240716A: GECAM-B detection of a long burst
  79. GRB 240713A: 2.2m CAHA optical limit
  80. GRB 240715A: Swift/UVOT observations of the XRT sources.
  81. GRB 240715A: Swift-XRT observations
  82. GRB240713A: Swift/UVOT Upper LImits
  83. EP240708a: X-ray follow-up observations with Swift/XRT
  84. GRB 240715A: GECAM-C detection of a short burst
  85. Konus-Wind detection of GRB 240715A
  86. GRB 240713A: Swift-XRT observations
  87. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  88. GRB 240712A: Swift-XRT refined Analysis
  89. GRB 240715A: Swift ToO observations
  90. GRB 240712A ATCA radio observations
  91. IPN triangulation of GRB 240715A (short)
  92. GW s240422ed: Swift UVOT follow-up
  93. GRB 240712A: Swift/UVOT Upper Limits
  94. EP-WXT flaring star and the optical flaring activity during its decay phase
  95. The EP-WXT source triggered on July 14th is likely a flaring star
  96. GRB 240715A: Fermi GBM Final Real-time Localization
  97. GRB 240713A: Tiled Swift observations
  98. GRB 240713A: OHP/T120 optical upper limit
  99. GRB240713A: X-ray follow-up observation with EP-FXT
  100. GRB 240713B: AstroSat CZTI detection of a long burst

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