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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"

37257 results found.

  1. IPN triangulation of GRB 250804B (short)
  2. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  3. GRB 250818B: Kilonova-Catcher optical afterglow detection
  4. GRB 250818B: Liverpool Telescope optical detections
  5. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  6. GRB 250818A: AstroSat CZTI detection
  7. GRB 250818B: Swift/UVOT Detection
  8. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  9. GRB 250820A: Fermi GBM Final Real-time Localization
  10. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  11. GRB 250818B: TRT Optical Observation
  12. Fermi GRB 250816A: Global MASTER-Net observations report
  13. GRB 250818B: SAO RAS optical observations
  14. Swift GRB 250818A: Global MASTER-Net observations report
  15. GRB 250818B: NOT optical observations
  16. GRB 250818A: Swift-XRT refined Analysis
  17. GRB 250818B: EP-FXT counterpart detection
  18. GRB 250818A: Swift-BAT refined analysis
  19. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  20. GRB 250818C: Fermi GBM Final Real-time Localization
  21. GRB 250818B: Keck redshift of the optical afterglow
  22. GRB 250818B: KAIT optical observations
  23. GRB 250818A: Swift/UVOT Upper Limits
  24. GRB 250818A: Enhanced Swift-XRT position
  25. GRB 250813B: SVOM/ECLAIRs refined analysis
  26. GRB 250818A: Fermi GBM Observation
  27. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  28. GRB 250818B: SVOM/VT optical observation
  29. GRB 250814A: Further GRAWITA TNG NIR observations
  30. GRB 250818B: Swift-XRT afterglow detection
  31. GRB 250818B: GOTO optical counterpart candidate
  32. GRB 250818B: SVOM detection of a short burst
  33. GRB 250818A: Swift detection of a burst
  34. GRB 250818A: Fermi GBM Final Real-time Localization
  35. GRB 250816A: SVOM/GRM observation of a short burst
  36. Fermi GRB 250814B: Global MASTER-Net observations report
  37. GRB 250816A: Fermi GBM Final Real-time Localization
  38. GRB 250814A: Swift-BAT refined analysis
  39. GRB 250815A: Fermi GBM Final Localization
  40. GRB 250813B: Liverpool Telescope optical upper limits
  41. GRB 250814A: Further COLIBRÍ optical upper limit
  42. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  43. GRB 250814A: GRAWITA TNG NIR observations
  44. GRB 250812A: SVOM/VT optical continued observation
  45. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  46. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  47. GRB250814A: TRT optical upper limits
  48. GRB 250814B: SVOM/GRM observation
  49. GRB 250814C: SVOM/GRM observation of a short burst
  50. GRB 250813B: SVOM/GRM observation
  51. GRB 250814A: P200/WIRC observations of the afterglow candidate
  52. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  53. GRB 250814A: KAIT optical upper limit
  54. GRB 250814A: Swift-XRT refined Analysis
  55. GRB 240814A: Fermi GBM Observation
  56. GRB 250814A: Possible afterglow candidate from P200/WIRC
  57. GRB 250813B: Fermi GBM Observation
  58. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  59. GRB 250814A: J-band upper limit from WINTER
  60. GRB 250813B: NOT observations of the optical afterglow
  61. GRB 250813B: SVOM/VT optical observations
  62. Subject GRB 250813B: SVOM/MXT refined analysis
  63. GRB 250814A: COLIBRÍ optical upper limit
  64. GRB 250814B: Fermi GBM Final Real-time Localization
  65. GRB 250813A: AstroSat CZTI detection
  66. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  67. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  68. GRB 250814A: DDOTI Optical Upper Limit
  69. GRB 250813B: EP-FXT counterpart detection
  70. GRB 250813B: Swift-XRT afterglow detection
  71. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  72. GRB 250814A: Fermi GBM Final Real-time Localization
  73. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  74. GRB 250813B: Ondrejov D50 fast decay
  75. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  76. GRB 250813B: Ondrejov D50 optical afterglow detection
  77. GRB 250813B: SVOM detection of a bright long burst
  78. EP250812a: Nickel optical upper limit
  79. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  80. GRB 250812A: NTT spectroscopic redshift z = 2.57
  81. GRB 250812A: Swift/UVOT Detection
  82. GRB 250813A: Fermi GBM Final Localization
  83. EP250812a: SVOM/VT optical counterpart
  84. GRB 250812A: EP-FXT counterpart detection
  85. GRB 250812A: Swift ToO observations
  86. GRB 250807B: Swift-BAT refined analysis
  87. GRB 250812A: Kilonova-Catcher optical afterglow detection
  88. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  89. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  90. GRB 250812A: SVOM/VT optical afterglow confirmation
  91. GRB 250812A: Swift-XRT afterglow detection
  92. GRB 250812A: TRT likely optical counterpart detection
  93. GRB 250812A: SVOM detection of a faint long burst
  94. GRB 250809A: Swift-BAT refined analysis
  95. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  96. GRB 250807A: Swift-BAT refined analysis
  97. GRB 250809A: Swift/UVOT Detection
  98. Corrected Swift-XRT Refined Analysis of GRB 250809A
  99. GRB 250809A: Swift-XRT refined Analysis
  100. GRB 250807B: SVOM/VT optical observation

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