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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').
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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"

39230 results found.

  1. GRB 240805A: Fermi GBM Final Real-time Localization
  2. Fermi GRB 240804A: Global MASTER-Net observations report
  3. EP240802a: Montarrenti Observatory optical upper limit
  4. GRB 240804A: Fermi GBM Final Real-time Localization
  5. Fermi trigger No 744459130: Global MASTER-Net observations report
  6. IPN triangulation of GRB 240802A / EP 240802a
  7. Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
  8. EP240802A: Bassano Bresciano Observatory upper limit
  9. GRB 240802A: SVOM/GRM observation
  10. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  11. Fermi trigger No 744278264: Global MASTER-Net observations report
  12. GRB 240802A: AstroSat CZTI detection of a long burst
  13. EP240801a: further SAO RAS optical observations
  14. EP240801a: optical observations at CrAO and AbAO
  15. EP240801a: Leavitt Observatory optical observations
  16. EP240801a: GTC spectroscopy and absorption redshift
  17. EP240801a: SAO RAS optical observations
  18. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  19. EP240801a: JinShan optical observations
  20. GRB 240727C: SVOM/GRM observation
  21. EP240801a: follow-up observation with LCOGT
  22. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  23. GRB 240730A: Swift-BAT refined analysis
  24. EP240801a: GSP follow-up observations of the candidate counterpart
  25. Fermi trigger No 744204856: Global MASTER-Net observations report
  26. EP240801a: KAIT optical counterpart observations
  27. EP240801a: TRT optical counterpart detection
  28. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  29. GRB 240801B: AstroSat CZTI detection of a bright long burst
  30. Fermi GRB 240801A: Global MASTER-Net observations report
  31. GRB 240801A: Fermi GBM Final Real-time Localization
  32. GRB 240730C: AstroSat CZTI detection of a long burst
  33. GRB 240731A: Fermi GBM Final Localization
  34. Fermi trigger No 744128417: Global MASTER-Net observations report
  35. Fermi trigger No 744083370: Global MASTER-Net observations report
  36. GRB 240731A: AstroSat CZTI detection
  37. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  38. GRB240730A: BOOTES-5/JGT early optical upper limit
  39. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  40. Fermi GRB 240730B: Global MASTER-Net observations report
  41. GRB 240730B: Fermi GBM Final Real-time Localization
  42. Swift GRB 240730A: Global MASTER-Net observations report
  43. GRB 240730A: Swift-XRT refined Analysis
  44. GRB 240715A: Swift-XRT afterglow detection
  45. GRB 240730A: KAIT Optical Upper Limit
  46. GRB 240727C: GRBAlpha detection
  47. GRB 240730A: Swift/UVOT Upper Limits
  48. GRB 240730A: Enhanced Swift-XRT position
  49. GRB 240730A: Swift detection of a burst
  50. Fermi trigger No 743953682: Global MASTER-Net observations report
  51. GRB 240727A: Swift-BAT refined analysis
  52. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  53. GRB 240727A: observations of optical counterpart.
  54. GRB 240727B: Swift-XRT observations
  55. Fermi GRB 240727A: Global MASTER-Net observations report
  56. GRB 240727A: Swift/UVOT detection
  57. Fermi trigger No 743868421: Global MASTER-Net observations report
  58. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  59. GRB 240727A: Correction to time in GCN36960
  60. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  61. GRB 240727A: NOT optical observation
  62. GRB 240727A: JinShan optical upper limits
  63. GRB 240727A Bassano Bresciano Observatory upper limit
  64. GRB 240727D: Correction to the GRB name in GCN 36958
  65. GRB 240727A: Fermi GBM Final Real-time Localization
  66. GRB 240727C: AstroSat CZTI detection of a long burst
  67. GRB 240727A: Swift-XRT refined Analysis
  68. GRB 240720B: GRBAlpha detection
  69. GRB 240718A: GRBAlpha detection
  70. GRB 240710B: GRBAlpha detection
  71. GRB 240627A: GRBAlpha detection
  72. Fermi GRB 240726A: Global MASTER-Net observations report
  73. GRB 240727A: Enhanced Swift-XRT position
  74. GRB 240727B: Fermi GBM Observation
  75. Swift GRB240727.16: Global MASTER-Net observations report
  76. GRB 240727B: Swift ToO observations
  77. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  78. GRB 240726A: SVOM/GRM observation
  79. GRB 240727B: AstroSat CZTI detection
  80. GRB 240726B: AstroSat CZTI detection of a short burst
  81. GRB240727A: Skynet Optical Afterglow Observations
  82. GRB 240727A: TRT optical afterglow detection
  83. GRB 240727A: KAIT Optical Afterglow Candidate
  84. GRB 240727A: Swift detection of a burst
  85. GRB 240726A: AstroSat CZTI detection of a short burst
  86. GRB 240726A: Fermi GBM Final Real-time Localization
  87. Fermi-LAT gamma-ray observations of IceCube-240725A
  88. IceCube Alert 240725.22: Global MASTER-Net observations report
  89. Swift Trigger 1244778 is not a GRB
  90. Swift GRB240725.11: Global MASTER-Net observations report
  91. GRB 240720A: Swift-BAT refined analysis
  92. Fermi trigger No 743418632: Global MASTER-Net observations report
  93. Fermi trigger No 743315411: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  95. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  96. Fermi trigger No 743345551: Global MASTER-Net observations report
  97. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  98. Fermi trigger No 743219692: Global MASTER-Net observations report
  99. IceCube Alert 240721.68: Global MASTER-Net observations report
  100. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB

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