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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

16270 results found.

  1. GRB 210410A: MITSuME Akeno optical upper limits
  2. GRB 210411C: BOOTES-4/MET optical upper limit
  3. GRB 210411C: LCO Optical Afterglow Candidate
  4. GRB 210406A: 10.4m GTC follow-up observation
  5. GRB 210411C: Swift detection of a burst with an optical counterpart
  6. GRB 210410A: Swift/UVOT Upper Limits
  7. GRB210410A: Joint inspection of RATIR and D50 data
  8. GRB 210406A: Swift-XRT observations
  9. GRB 210410A: RATIR Optical and NIR Observations
  10. GRB210410A: Candidate optical afterglow by Ondrejov D50
  11. GRB 210406A: Mondy optical afterglow candidate
  12. GRB 210406A: Mondy optical upper limit
  13. GRB 210406A: Konkoly Obs. optical upper limit
  14. GRB 210406A: BOOTES-4/MET optical upper limit
  15. GRB 210402A: MASTER prompt and follow up optical observation
  16. GRB 210402A: Swift/UVOT Upper Limits
  17. GRB 210402A: Further NOT optical observations
  18. GRB 210207B: Prompt and very late time observations with HCT.
  19. GRB 210402A: NOT optical afterglow candidate
  20. GRB 210402A: BOOTES-network early optical upper limit
  21. GRB 210402A: Montarrenti Observatory upper limit
  22. GRB 210402A: NOT optical upper limits
  23. GRB 210330A: MASTER optical observation
  24. GRB 210321A: OSN Upper Limit
  25. GRB 210323A: MASTER optical observation
  26. GRB 210323A: Gemini-North Optical Source Detection
  27. GRB 210312B: OSN Afterglow Observations
  28. GRB 210323A: Swift/UVOT Upper Limits
  29. GRB 210323A: Kitab optical upper limit
  30. GRB 210323A: Mondy optical observations, counterpart detection
  31. GRB 210318A: Swift/UVOT Upper Limits
  32. GRB 210323A: NOT optical afterglow candidate
  33. GRB 210323A: Nanshan/NEXT optical upper limit
  34. GRB 210318B: Swift/UVOT Upper Limits
  35. GRB 210321A: CrAO optical upper limit
  36. GRB 210321A: Mondy optical observations
  37. GRB 210321A: Xinglong GWAC-F60A optical observation
  38. GRB 210321A: NOT optical afterglow detection and redshift limit
  39. GRB 210321A: MASTER optical observation
  40. GRB 210318B: MITSuME Okayama optical upper limits
  41. GRB 201216C: VIRT optical observations
  42. GRB 210306A: GIT optical follow-up
  43. GRB 210226A: GIT optical upper limit
  44. GRB 210306A: HCT optical upper limit
  45. GRB 210312B: MASTER OT confirmation
  46. GRB210312B (Integral alert 9073): Candidate optical afterglow by Ondrejov D50
  47. GRB 210306A: Tautenburg observations
  48. GRB 171205A: Continued ATCA observations
  49. GRB 210306A: Early Spectroscopy of the Optical Afterglow
  50. GRB 210306A: continued Mondy optical observations
  51. GRB 210308A: Mondy and AbAO optical observations
  52. GRB 210307A: Swift/UVOT Upper Limits
  53. GRB 210308A: Nanshan/NEXT optical upper limits
  54. GRB 210308A: MITSuME Okayama optical upper limits
  55. GRB 210306A: continued Mondy optical observations
  56. GRB 210308A: Swift detection of a burst with an optical counterpart
  57. GRB 210306A: 1.3m DFOT observations
  58. GRB 210306A: Mondy optical observations
  59. GRB 210305A: Swift/UVOT Upper Limits
  60. GRB 210307A: LCO Optical Upper Limits
  61. GRB 210306A: MITSuME Akeno optical observation
  62. GRB 210306A: NEXT optical observations
  63. GRB 210306A: iTelescope T24 optical observations
  64. GRB 210306A: LCO Optical Afterglow Detection
  65. GRB 210306A: iTelescope optical afterglow observations
  66. GRB 210306A: Swift detection of a burst with a bright optical counterpart
  67. GRB 210217A: 3.6m DOT optical observations
  68. GRB 210226A: Swift/UVOT Upper Limits
  69. Integral GRB210227.19: MASTER OT retraction
  70. Integral GRB210227.19: Global MASTER-Net OT detection
  71. GRB 210217A: Mondy optical observations
  72. GRB 210226A: KAIT Optical Upper Limit
  73. GRB 210226A: Burke-Gaffney Observatory optical upper limit
  74. GRB 210226A: Ondrejov BART/SBT optical limit
  75. GRB 210222B: 1.3m DFOT Optical upper limit
  76. GRB 210222B: REM observations of the optical/NIR afterglow
  77. GRB 210222B: MITSuME Akeno optical upper limits
  78. GRB 210222B: Zeiss-1000 of Koshka observatory, optical observations
  79. GRB 210222B: VIRT optical detection
  80. GRB 210222B: Swift/UVOT Detection
  81. GRB 210222B: KAIT Optical Upper Limit
  82. GRB 210218A: Swift/UVOT observations
  83. GRB 210222B: MASTER OT observation
  84. GRB 210222B: NEXT early optical afterglow observations
  85. GRB 210222B: Liverpool Telescope optical detection
  86. GRB 210222B: GOTO confirmation of afterglow detection
  87. GRB210222B: LCO Optical Afterglow Detection
  88. GRB210222B: BOOTES-1 optical afterglow detection
  89. GRB 210222B: Swift detection of a burst with an optical counterpart
  90. GRB 210217A: 1.3m DFOT optical detection
  91. GRB 210217A: Liverpool Telescope First Hour Observations
  92. GRB 210217A: KAIT Optical Observations
  93. GRB 210218A: MITSuME Akeno optical upper limits
  94. GRB 210218A： GWAC-F60A optical upper limit
  95. GRB 210218A: NEXT optical upper limit
  96. ZTF21aakruew/AT2021cwd: GROND observations
  97. GRB 210212A: REM early-time optical/NIR upper limits
  98. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  99. GRB 210217A: NEXT early optical afterglow observations
  100. GRB 210212A: Mondy optical observations

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