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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 240727D: Correction to the GRB name in GCN 36958
  2. GRB 240727A: Fermi GBM Final Real-time Localization
  3. GRB 240727C: AstroSat CZTI detection of a long burst
  4. GRB 240727A: Swift-XRT refined Analysis
  5. GRB 240720B: GRBAlpha detection
  6. GRB 240718A: GRBAlpha detection
  7. GRB 240710B: GRBAlpha detection
  8. GRB 240627A: GRBAlpha detection
  9. Fermi GRB 240726A: Global MASTER-Net observations report
  10. GRB 240727A: Enhanced Swift-XRT position
  11. GRB 240727B: Fermi GBM Observation
  12. Swift GRB240727.16: Global MASTER-Net observations report
  13. GRB240529A: VIRT optical transient detection
  14. GRB 240727B: Swift ToO observations
  15. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  16. GRB 240726A: SVOM/GRM observation
  17. GRB 240727B: AstroSat CZTI detection
  18. GRB 240726B: AstroSat CZTI detection of a short burst
  19. GRB240727A: Skynet Optical Afterglow Observations
  20. GRB 240727A: TRT optical afterglow detection
  21. GRB 240727A: KAIT Optical Afterglow Candidate
  22. GRB 240727A: Swift detection of a burst
  23. GRB 240726A: AstroSat CZTI detection of a short burst
  24. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 240726A: Fermi GBM Final Real-time Localization
  26. Fermi-LAT gamma-ray observations of IceCube-240725A
  27. IceCube Alert 240725.22: Global MASTER-Net observations report
  28. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  29. Swift Trigger 1244778 is not a GRB
  30. Swift GRB240725.11: Global MASTER-Net observations report
  31. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  32. GRB 240720A: Swift-BAT refined analysis
  33. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  34. Fermi trigger No 743418632: Global MASTER-Net observations report
  35. Fermi trigger No 743315411: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  37. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  38. Fermi trigger No 743345551: Global MASTER-Net observations report
  39. Fermi-LAT gamma-ray observations of IceCube-240721A
  40. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  41. Fermi trigger No 743219692: Global MASTER-Net observations report
  42. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  43. IceCube Alert 240721.68: Global MASTER-Net observations report
  44. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  45. GRB 240720B: SVOM/GRM observation
  46. GRB 240721A: Fermi GBM Final Real-time Localization
  47. GRB 240720B: AstroSat CZTI detection of a short burst
  48. Fermi GRB 240720A: Global MASTER-Net observations report
  49. GRB 240720A: AstroSat CZTI detection
  50. GRB 240720A: Fermi GBM observation
  51. GRB 240720A: Swift detection of a burst
  52. Swift GRB240720.02: Global MASTER-Net observations report
  53. Konus-Wind detection of GRB 240718A
  54. GRB 240713A: SVOM/GRM observation
  55. Fermi GRB 240718A: Global MASTER-Net observations report
  56. LAT GRB240718.27: Global MASTER-Net observations report
  57. GRB 240718A: Fermi GBM Observation
  58. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  59. GRB 240718A: Fermi-LAT Detection
  60. GRB 240718A: SVOM/GRM observation
  61. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  62. GRB 240718A: Fermi GBM Final Real-time Localization
  63. GRB 240712A: Swift-BAT refined analysis
  64. GRB 240716A: GECAM-B detection of a long burst
  65. SVOM/GRM In-Flight Trigger of GRB 240716A
  66. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  67. GRB 240713A: 2.2m CAHA optical limit
  68. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  69. GRB 240715A: Swift/UVOT observations of the XRT sources.
  70. GRB 240715A: Swift-XRT observations
  71. GRB240713A: Swift/UVOT Upper LImits
  72. EP240708a: X-ray follow-up observations with Swift/XRT
  73. GRB 240715A: GECAM-C detection of a short burst
  74. Konus-Wind detection of GRB 240715A
  75. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  76. GRB 240713A: Swift-XRT observations
  77. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  78. GRB 240712A: Swift-XRT refined Analysis
  79. SVOM/GRM In-Flight Trigger of GRB 240715A
  80. GRB 240713A: LAST optical upper limit
  81. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  82. GRB 240715A: Swift ToO observations
  83. Fermi GRB 240715A: Global MASTER-Net observations report
  84. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  85. GRB 240715A: Fermi GBM Observation
  86. GRB 240712A ATCA radio observations
  87. GRB240715A: GRANDMA Optical Upper Limits
  88. IPN triangulation of GRB 240715A (short)
  89. GW s240422ed: Swift UVOT follow-up
  90. GRB 240712A: Swift/UVOT Upper Limits
  91. EP-WXT flaring star and the optical flaring activity during its decay phase
  92. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  93. The EP-WXT source triggered on July 14th is likely a flaring star
  94. GRB 240715A: Fermi GBM Final Real-time Localization
  95. GRB 240713A: Tiled Swift observations
  96. GRB 240713A: J-band upper limit from WINTER
  97. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  98. GRB 240713A: JinShan optical upper limits
  99. GRB 240713A: OHP/T120 optical upper limit
  100. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)

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