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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. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  2. GRB 210104A: Mondy optical observations, light curve
  3. MAXI GRB210110.64: Global MASTER-Net observations report
  4. GRB 210110A: MAXI/GSC detection
  5. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  6. GRB 210109A: MAXI/GSC detection
  7. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  8. Correction to GCN 29278: GRB 201216C XRT refined analysis
  9. GRB 210108A: BALROG localization (Fermi Trigger 631793415 / GRB 210108424)
  10. GRB 201216C: Swift-XRT refined Analysis
  11. GRB 210104A: SAO RAS optical observations
  12. GRB 201227A: ASIM observation
  13. GRB 210104A: GMG observations
  14. GRB210104A: VIRT optical transient detection.
  15. GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
  16. Fermi trigger No 631602681: Global MASTER-Net observations report
  17. GRB 210102B: further Swift-XRT observations
  18. GRB 210102B: Assy optical afterglow identification
  19. GRB 210104A: iTelescope optical upper limit
  20. GRB 210104A: CALET Gamma-Ray Burst Monitor detection
  21. Fermi trigger No 631584650: Global MASTER-Net observations report
  22. GRB 210104B: Swift-BAT refined analysis
  23. GRB 210104A: Assy continued optical observations
  24. Fermi GRB 210105A: Global MASTER-Net observations report
  25. GW170817: HST observations at 3.4 years from merger
  26. GRB 210104A: early ATLAS detections of the bright afterglow
  27. GRB 210105A: Fermi GBM Final Real-time Localization
  28. GRB 210104A: Swift-XRT refined Analysis
  29. GRB 210104B: Swift/UVOT Upper Limits
  30. Konus-Wind detection of GRB 210104A
  31. GRB 210104A: 1.3m DFOT Optical Afterglow Detection
  32. GRB 210104B: Swift-XRT refined Analysis
  33. GRB 210104B: Assy optical upper limit
  34. GRB 210104A: DOAO optical afterglow observations
  35. GRB 210104B: Enhanced Swift-XRT position
  36. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  37. GRB 210104A: Swift-BAT refined analysis
  38. GRB 210104B: Nanshan/NEXT optical upper limit
  39. GRB 210104B: BOOTES network optical upper limit
  40. GRB 210104A: MASTER OT rebrightening detection
  41. GRB 210104A: Swift/UVOT Detection
  42. GRB 210104A: Fermi GBM detection
  43. GRB 210104A: Enhanced Swift-XRT position
  44. GRB 210102B: Tiled Swift observations
  45. GRB 210104B: Swift detection of a burst
  46. Swift GRB210104.88: Global MASTER-Net observations report
  47. GRB 210104A: MITSuME Ishigaki optical observation
  48. GRB 210102B: Assy optical observations
  49. Fermi GRB 210104A: Global MASTER-Net observations report
  50. GRB 210104A: Assy optical observations
  51. GRB 210104A: MITSuME Akeno optical observation
  52. GRB 210104A: BOOTES-4/MET early optical afterglow detection
  53. GRB 210104A: GWAC-F60A optical afterglow observations
  54. GRB 210104A: BALROG localization (Fermi Trigger 631452424 / GRB 210104477)
  55. GRB 210104A: Swift detection of a burst with a bright optical counterpart
  56. GRB 210104A: Fermi GBM Final Real-time Localization
  57. GRB 210102C: Swift-BAT refined analysis
  58. GRB 210102B: Swift-XRT observations
  59. Fermi GRB 210102C: Global MASTER-Net observations report
  60. GRB 210102C: Fermi GBM detection
  61. Swift GRB 210102C: Global MASTER-Net observations report
  62. GRB 210102C: Swift detection of a burst
  63. MAXI GRB210102.38: Global MASTER-Net observations report
  64. GRB 210102B: Tiled Swift observations
  65. GRB 210102B: MAXI/GSC detection
  66. Fermi GRB 210101A: Global MASTER-Net observations report
  67. INTEGRAL Weak #8913: AROMA-N Optical Observation
  68. Swift Trigger 1015615 is not a GRB
  69. Swift GRB210102.01: Global MASTER-Net observations report
  70. Fermi trigger No 631226368: Global MASTER-Net observations report
  71. Fermi trigger No 631119348: Global MASTER-Net observations report
  72. GRB 210101A: BALROG localization (Fermi Trigger 631205591 / GRB 210101620)
  73. GRB 210101A: Fermi GBM Final Real-time Localization
  74. Fermi trigger No 631113166: Global MASTER-Net observations report
  75. GRB 201229A: Swift/UVOT Detection
  76. Fermi trigger No 631118376: Global MASTER-Net observations report
  77. Fermi trigger No 631104264: Global MASTER-Net observations report
  78. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  79. Baksan Neutrino Observatory Alert 201230.40: Global MASTER-Net observations report
  80. GRB 201227A: Chilescope optical observations, possible optical counterpart
  81. GRB 201227A: GRAWITA VST-ESO PARANAL observations
  82. GRB 201227A: Fermi GBM observation
  83. GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
  84. GRB 201229A: SAO RAS optical observations
  85. GRB 201229A: Nanshan/NEXT optical upper limit
  86. GRB 201227A: Swift-XRT observations
  87. GRB 201223A: SVOM-GWAC detected the optical counterpart during prompt emission phase
  88. GRB 201229A: Swift-XRT refined Analysis
  89. GRB 201229A: Swift-BAT refined analysis
  90. GRB 201104B: Maidanak and CrAO optical observations
  91. Fermi GRB 201229B: Global MASTER-Net observations report
  92. Konus-Wind observation of GRB 201227A
  93. GRB 201229B: BALROG localization (Fermi Trigger 630948017 / GRB 201229639)
  94. GRB 201229B: Fermi GBM Final Real-time Localization
  95. GRB 201229A: Enhanced Swift-XRT position
  96. GRB 201229A: Swift detection of a burst with a possible optical counterpart
  97. GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
  98. Baksan Neutrino Observatory Alert 201228.36: Global MASTER-Net observations report
  99. Fermi GRB 201228B: Global MASTER-Net observations report
  100. GRB 201228B: Fermi GBM Final Real-time Localization

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