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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"

36139 results found.

  1. GRB 240802A: AstroSat CZTI detection of a long burst
  2. EP240801a: further SAO RAS optical observations
  3. EP240801a: optical observations at CrAO and AbAO
  4. EP240801a: Leavitt Observatory optical observations
  5. EP240801a: SAO RAS optical observations
  6. GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
  7. GRB 240727C: SVOM/GRM observation
  8. Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
  9. GRB 240730A: Swift-BAT refined analysis
  10. EP240801a: KAIT optical counterpart observations
  11. GRB 240801B: AstroSat CZTI detection of a bright long burst
  12. Fermi GRB 240801A: Global MASTER-Net observations report
  13. GRB 240801A: Fermi GBM Final Real-time Localization
  14. GRB 240730C: AstroSat CZTI detection of a long burst
  15. GRB 240731A: Fermi GBM Final Localization
  16. GRB 240731A: AstroSat CZTI detection
  17. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  18. GRB240730A: BOOTES-5/JGT early optical upper limit
  19. Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
  20. Fermi GRB 240730B: Global MASTER-Net observations report
  21. GRB 240730B: Fermi GBM Final Real-time Localization
  22. Swift GRB 240730A: Global MASTER-Net observations report
  23. GRB 240730A: Swift-XRT refined Analysis
  24. GRB 240715A: Swift-XRT afterglow detection
  25. GRB 240730A: KAIT Optical Upper Limit
  26. GRB 240727C: GRBAlpha detection
  27. GRB 240730A: Swift/UVOT Upper Limits
  28. GRB 240730A: Enhanced Swift-XRT position
  29. GRB 240730A: Swift detection of a burst
  30. GRB 240727A: Swift-BAT refined analysis
  31. Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
  32. GRB 240727A: observations of optical counterpart.
  33. GRB 240727B: Swift-XRT observations
  34. Fermi GRB 240727A: Global MASTER-Net observations report
  35. GRB 240727A: Swift/UVOT detection
  36. Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
  37. GRB 240727A: Correction to time in GCN36960
  38. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  39. GRB 240727A: NOT optical observation
  40. GRB 240727A: JinShan optical upper limits
  41. GRB 240727A Bassano Bresciano Observatory upper limit
  42. GRB 240727D: Correction to the GRB name in GCN 36958
  43. GRB 240727A: Fermi GBM Final Real-time Localization
  44. GRB 240727C: AstroSat CZTI detection of a long burst
  45. GRB 240727A: Swift-XRT refined Analysis
  46. GRB 240720B: GRBAlpha detection
  47. GRB 240718A: GRBAlpha detection
  48. GRB 240710B: GRBAlpha detection
  49. GRB 240627A: GRBAlpha detection
  50. Fermi GRB 240726A: Global MASTER-Net observations report
  51. GRB 240727A: Enhanced Swift-XRT position
  52. GRB 240727B: Fermi GBM Observation
  53. GRB 240727B: Swift ToO observations
  54. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  55. GRB 240726A: SVOM/GRM observation
  56. GRB 240727B: AstroSat CZTI detection
  57. GRB 240726B: AstroSat CZTI detection of a short burst
  58. GRB240727A: Skynet Optical Afterglow Observations
  59. GRB 240727A: TRT optical afterglow detection
  60. GRB 240727A: KAIT Optical Afterglow Candidate
  61. GRB 240727A: Swift detection of a burst
  62. GRB 240726A: AstroSat CZTI detection of a short burst
  63. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 240726A: Fermi GBM Final Real-time Localization
  65. Swift Trigger 1244778 is not a GRB
  66. GRB 240720A: Swift-BAT refined analysis
  67. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  68. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  69. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  70. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  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. Konus-Wind detection of GRB 240718A
  80. GRB 240713A: SVOM/GRM observation
  81. Fermi GRB 240718A: Global MASTER-Net observations report
  82. GRB 240718A: Fermi GBM Observation
  83. GRB 240718A: Fermi-LAT Detection
  84. GRB 240718A: SVOM/GRM observation
  85. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  86. GRB 240718A: Fermi GBM Final Real-time Localization
  87. GRB 240712A: Swift-BAT refined analysis
  88. GRB 240716A: GECAM-B detection of a long burst
  89. SVOM/GRM In-Flight Trigger of GRB 240716A
  90. GRB 240713A: 2.2m CAHA optical limit
  91. GRB 240715A: Swift/UVOT observations of the XRT sources.
  92. GRB 240715A: Swift-XRT observations
  93. GRB240713A: Swift/UVOT Upper LImits
  94. GRB 240715A: GECAM-C detection of a short burst
  95. Konus-Wind detection of GRB 240715A
  96. GRB 240713A: Swift-XRT observations
  97. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  98. GRB 240712A: Swift-XRT refined Analysis
  99. SVOM/GRM In-Flight Trigger of GRB 240715A
  100. GRB 240713A: LAST optical upper limit

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