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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"

28726 results found.

  1. GRB 210306A: Early Spectroscopy of the Optical Afterglow
  2. GRB 210306B: Fermi GBM detection
  3. GRB 210306A: Swift/UVOT Detection
  4. GRB 210306A: continued Mondy optical observations
  5. GRB 210308A: Mondy and AbAO optical observations
  6. GRB 210308A: Swift-BAT refined analysis
  7. GRB 210307A: Swift-BAT refined analysis
  8. GRB 210308A: Swift/UVOT Detection
  9. GRB 210307A: Swift/UVOT Upper Limits
  10. GRB 210305A: Fermi GBM observation
  11. Swift GRB 210308A: Global MASTER-Net observations report
  12. GRB 210308A: Fermi GBM detection
  13. GRB 210305A: Swift-XRT refined Analysis
  14. GRB 210307A: Swift-XRT refined Analysis
  15. GRB 210308A: Nanshan/NEXT optical upper limits
  16. GRB 210306A: Swift-XRT refined Analysis
  17. GRB 210308A: MITSuME Okayama optical upper limits
  18. GRB 210306A: continued Mondy optical observations
  19. GRB 210306A: 1.3m DFOT observations
  20. GRB 210306A: Swift-BAT refined analysis
  21. GRB 210306A: Mondy optical observations
  22. GRB 210305A: Swift/UVOT Upper Limits
  23. GRB 210307A: LCO Optical Upper Limits
  24. GRB 210306B: Swift-BAT refined analysis
  25. GRB 210305A: Swift-BAT refined analysis
  26. GRB 210306A: MITSuME Akeno optical observation
  27. GRB 210306A: NEXT optical observations
  28. Swift GRB 210306A: Global MASTER-Net observations report
  29. GRB 210306A: Fermi GBM observation
  30. GRB 210306A: Tautenburg observations
  31. GRB 210306A: Fermi-LAT detection
  32. GRB 210306A: LCO Optical Afterglow Detection
  33. GRB 210306A: iTelescope optical afterglow observations
  34. GRB 210306A: DDOTI Afterglow Confirmation
  35. Swift GRB 210305A: Global MASTER-Net observations report
  36. GRB 210217A: 3.6m DOT optical observations
  37. GRB 210226A: Swift/UVOT Upper Limits
  38. Integral GRB210227.19: MASTER OT retraction
  39. GRB 210226A: Swift-BAT refined analysis
  40. GRB 210226A: Fermi GBM detection
  41. GRB 210217A: Mondy optical observations
  42. GRB 210226A: KAIT Optical Upper Limit
  43. GRB 210226A: Swift-XRT refined Analysis
  44. Swift GRB 210226A: Global MASTER-Net observations report
  45. GRB 210218A: Swift-XRT confirmation of afterglow
  46. GRB 210226A: Burke-Gaffney Observatory optical upper limit
  47. GRB 210222B: 1.3m DFOT Optical upper limit
  48. GRB 210222B: REM observations of the optical/NIR afterglow
  49. GRB 210222B: MITSuME Akeno optical upper limits
  50. Konus-Wind detection of GRB 210222A
  51. GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
  52. GRB 210222B: VIRT optical detection
  53. GRB 210222B: Swift-BAT refined analysis
  54. GRB 210222B: Swift-XRT refined Analysis
  55. GRB 210222B: Swift/UVOT Detection
  56. GRB 210222B: KAIT Optical Upper Limit
  57. GRB 210218A: Swift/UVOT observations
  58. GRB 210217A: Swift/UVOT Detection
  59. GRB 210222B: MASTER OT observation
  60. GRB 210222A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 210222B: Redshift from FORS2/VLT
  62. GRB 210222B: NEXT early optical afterglow observations
  63. GRB 210222B: GOTO confirmation of afterglow detection
  64. GRB210222B: LCO Optical Afterglow Detection
  65. GRB 210218A: Swift-XRT observations
  66. uGMRT radio detection of GRB 210204A
  67. GRB 210212A: Lowell Discovery Telescope observations
  68. GRB 210217A: 1.3m DFOT optical detection
  69. GRB 210217A: Swift-XRT refined Analysis
  70. GRB 210218A: Swift-BAT refined analysis
  71. Fermi GBM Sub-Threshold Detection of GRB 210217A
  72. GRB 210217A: Liverpool Telescope First Hour Observations
  73. GRB 210217A: Swift-BAT refined analysis
  74. GRB 210217A: KAIT Optical Observations
  75. GRB 210218A: MITSuME Akeno optical upper limits
  76. GRB 210218A： GWAC-F60A optical upper limit
  77. GRB 210218A: NEXT optical upper limit
  78. ZTF21aakruew/AT2021cwd: GROND observations
  79. GRB 210212A: REM early-time optical/NIR upper limits
  80. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  81. Fermi/GBM observation of a burst from SGR 1830-0645
  82. GRB 210217A: NEXT early optical afterglow observations
  83. GRB 210212A: Mondy optical observations
  84. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  85. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  86. GRB 210208A: 1.3m DFOT Optical upper limit
  87. GRB 210210A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  88. Swift Trigger 1033144: Detection of SGR 1830-0645
  89. GRB 210211A: ePESSTO+ NTT optical observations
  90. Konus-Wind detection of GRB 210212B / ZTF21aakruew
  91. GRB 210212B: Swift ToO observations
  92. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  93. IPN triangulation of GRB 210212B (consistent with ZTF21aakruew/AT2021cwd)
  94. GRB 210212A: 1.3m DFOT Optical upper limit
  95. GRB 210212A: Gemini South optical observations
  96. Fermi GRB 210213A: Global MASTER-Net observations report
  97. GRB 210210A: CAHA 2nd epoch and jet break confirmation
  98. IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
  99. Swift Trigger 1032350: Detection of SGR 1830-0645
  100. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations

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