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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 240727C: AstroSat CZTI detection of a long burst
  2. GRB 240727A: Swift-XRT refined Analysis
  3. GRB 240720B: GRBAlpha detection
  4. GRB 240718A: GRBAlpha detection
  5. GRB 240710B: GRBAlpha detection
  6. GRB 240627A: GRBAlpha detection
  7. Fermi GRB 240726A: Global MASTER-Net observations report
  8. GRB 240727A: Enhanced Swift-XRT position
  9. GRB 240727B: Fermi GBM Observation
  10. Swift GRB240727.16: Global MASTER-Net observations report
  11. GRB240529A: VIRT optical transient detection
  12. GRB 240727B: Swift ToO observations
  13. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  14. GRB 240726A: SVOM/GRM observation
  15. GRB 240727B: AstroSat CZTI detection
  16. GRB 240726B: AstroSat CZTI detection of a short burst
  17. GRB240727A: Skynet Optical Afterglow Observations
  18. GRB 240727A: TRT optical afterglow detection
  19. GRB 240727A: KAIT Optical Afterglow Candidate
  20. GRB 240727A: Swift detection of a burst
  21. GRB 240726A: AstroSat CZTI detection of a short burst
  22. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 240726A: Fermi GBM Final Real-time Localization
  24. Fermi-LAT gamma-ray observations of IceCube-240725A
  25. IceCube Alert 240725.22: Global MASTER-Net observations report
  26. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  27. Swift Trigger 1244778 is not a GRB
  28. Swift GRB240725.11: Global MASTER-Net observations report
  29. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  30. GRB 240720A: Swift-BAT refined analysis
  31. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  32. Fermi trigger No 743418632: Global MASTER-Net observations report
  33. Fermi trigger No 743315411: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  35. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  36. Fermi trigger No 743345551: Global MASTER-Net observations report
  37. Fermi-LAT gamma-ray observations of IceCube-240721A
  38. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  39. Fermi trigger No 743219692: Global MASTER-Net observations report
  40. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  41. IceCube Alert 240721.68: Global MASTER-Net observations report
  42. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  43. GRB 240720B: SVOM/GRM observation
  44. GRB 240721A: Fermi GBM Final Real-time Localization
  45. GRB 240720B: AstroSat CZTI detection of a short burst
  46. Fermi GRB 240720A: Global MASTER-Net observations report
  47. GRB 240720A: AstroSat CZTI detection
  48. GRB 240720A: Fermi GBM observation
  49. GRB 240720A: Swift detection of a burst
  50. Swift GRB240720.02: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 240718A
  52. GRB 240713A: SVOM/GRM observation
  53. Fermi GRB 240718A: Global MASTER-Net observations report
  54. LAT GRB240718.27: Global MASTER-Net observations report
  55. GRB 240718A: Fermi GBM Observation
  56. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  57. GRB 240718A: Fermi-LAT Detection
  58. GRB 240718A: SVOM/GRM observation
  59. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  60. GRB 240718A: Fermi GBM Final Real-time Localization
  61. GRB 240712A: Swift-BAT refined analysis
  62. GRB 240716A: GECAM-B detection of a long burst
  63. SVOM/GRM In-Flight Trigger of GRB 240716A
  64. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  65. GRB 240713A: 2.2m CAHA optical limit
  66. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  67. GRB 240715A: Swift/UVOT observations of the XRT sources.
  68. GRB 240715A: Swift-XRT observations
  69. GRB240713A: Swift/UVOT Upper LImits
  70. EP240708a: X-ray follow-up observations with Swift/XRT
  71. GRB 240715A: GECAM-C detection of a short burst
  72. Konus-Wind detection of GRB 240715A
  73. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  74. GRB 240713A: Swift-XRT observations
  75. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  76. GRB 240712A: Swift-XRT refined Analysis
  77. SVOM/GRM In-Flight Trigger of GRB 240715A
  78. GRB 240713A: LAST optical upper limit
  79. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  80. GRB 240715A: Swift ToO observations
  81. Fermi GRB 240715A: Global MASTER-Net observations report
  82. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  83. GRB 240715A: Fermi GBM Observation
  84. GRB 240712A ATCA radio observations
  85. GRB240715A: GRANDMA Optical Upper Limits
  86. IPN triangulation of GRB 240715A (short)
  87. GW s240422ed: Swift UVOT follow-up
  88. GRB 240712A: Swift/UVOT Upper Limits
  89. EP-WXT flaring star and the optical flaring activity during its decay phase
  90. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  91. The EP-WXT source triggered on July 14th is likely a flaring star
  92. GRB 240715A: Fermi GBM Final Real-time Localization
  93. GRB 240713A: Tiled Swift observations
  94. GRB 240713A: J-band upper limit from WINTER
  95. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  96. GRB 240713A: JinShan optical upper limits
  97. GRB 240713A: OHP/T120 optical upper limit
  98. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  99. GRB240713A: X-ray follow-up observation with EP-FXT
  100. GRB 240713B: AstroSat CZTI detection of a long burst

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