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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"

27394 results found.

  1. GRB 210605B: Swift-XRT observations
  2. IPN triangulation of GRB 210605A (short)
  3. GRB 210606B: BALROG localization (Fermi Trigger 644712030 / GRB 210606945)
  4. GRB 210606B: GECAM detection
  5. Fermi GRB 210606A: DDOTI Upper Limits on the Afterglow
  6. GRB 210606A: Swift/BAT-GUANO detection and arcminute localization
  7. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  8. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  9. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  10. SGR J1555.2-5402: Swift-BAT refined analysis
  11. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  12. Swift Detection of probable new Swift SGR J1555.2-5402
  13. MAXI GRB210602.50: Global MASTER-Net observations report
  14. Swift GRB210603.41: Global MASTER-Net observations report
  15. GRB 210602B: GECAM detection
  16. GRB 210529A: GECAM detection
  17. GRB 210602A: MAXI/GSC detection
  18. GRB 210601A: Fermi GBM Final Real-time Localization
  19. IPN triangulation of GRB 210531A
  20. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  21. GRB 210531A: AstroSat CZTI detection
  22. Fermi trigger No 644155206: Global MASTER-Net observations report
  23. GRB 210531A: BALROG localization (Fermi Trigger 644155206 / GRB 210531500)
  24. GRB 210529B: DDOTI Upper Limits on the Afterglow
  25. GRB 210528A: Fermi GBM detection
  26. GRB 210528A: AstroSat CZTI detection
  27. GRB 210528B: DDOTI Upper Limits on the Afterglow
  28. GRB 210528B: MITSuME Akeno optical upper limits
  29. MAXI GRB210528.95: Global MASTER-Net observations report
  30. GRB 210528B: MAXI/GSC detection
  31. GRB 210527A: Swift-BAT refined analysis
  32. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  33. GRB 210527A: Swift/UVOT Observations
  34. GRB 210527A: GIT optical upper limit
  35. GRB 210527A: MITSuME Akeno optical upper limits
  36. GRB 210527A: Swift-XRT refined Analysis
  37. GRB 210527A: RATIR Optical and NIR Observations
  38. GRB 210527A: Enhanced Swift-XRT position
  39. GRB 210527A: Swift-XRT observations
  40. GRB 210306A: LBT observations of the likely host galaxy
  41. ZTF21aayokph (AT2021lfa): LBT optical observations
  42. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  43. Konus-Wind detection of GRB 210524A
  44. IPN triangulation of GRB 210524A
  45. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  46. GRB 210522A: GECAM detection
  47. GRB 210520A: Swift-XRT observations
  48. MAXI GRB210521.54: Global MASTER-Net observations report
  49. GRB 210521A: MAXI/GSC detection
  50. GRB210413B: further Swift-XRT observations
  51. GRB 210520A: Fermi GBM detection
  52. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  53. GRB 210520A: GECAM detection
  54. GRB 210517A: KCT optical upper limit
  55. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  56. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  57. IceCube Alert 210515.01: Global MASTER-Net observations report
  58. GRB 210517A: Swift-BAT refined analysis
  59. GRB 210517A: Swift-XRT refined Analysis
  60. IceCube-210516A: No significant detection in HAWC
  61. GRB 210517A: Swift/UVOT Upper Limits
  62. GRB 210515C: Swift/UVOT Upper Limits
  63. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  65. GRB 210517A: Enhanced Swift-XRT position
  66. GRB 210517A: Swift detection of a burst
  67. GRB 210515C: LCO Optical Upper Limit
  68. GRB 210504A: LCO Optical Afterglow Detection
  69. GRB 210514A: Swift/UVOT Upper Limits
  70. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  71. GRB 210515C: Swift-XRT refined Analysis
  72. GRB 210515C: Swift-BAT refined analysis
  73. GRB 210514A: Swift-BAT refined analysis
  74. Fermi GRB 210515A: Global MASTER-Net observations report
  75. GRB 210514A: Swift-XRT refined Analysis
  76. GRB 210514A: Enhanced Swift-XRT position
  77. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  78. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  79. Short GRB 210323A: likely host galaxy detection
  80. GRB 210511B: DDOTI Upper Limits on the Afterglow
  81. IPN triangulation of GRB 210427A
  82. GRB 210511B: Fermi GBM observation
  83. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  84. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  85. GRB 210511B: GECAM detection
  86. GRB 210511B: BALROG localization (Fermi Trigger 642425204 / GRB 210511477)
  87. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  88. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  89. IceCube-210510A: DDOTI Upper Limits
  90. GRB 210509A: RATIR Optical and NIR Upper Limits
  91. GRB 210509A: Swift/UVOT Upper Limits
  92. GRB 210509A: Swift-XRT refined Analysis
  93. GRB 210509A: Swift-BAT refined analysis
  94. GRB 210509A: Enhanced Swift-XRT position
  95. GRB 210509A: Swift-XRT observations
  96. GRB 210506A: Swift/BAT-GUANO position retraction
  97. HAWC-210507A: No neutrino counterpart candidates in ANTARES search
  98. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  99. GRB 210506A: Swift-XRT observations
  100. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF

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