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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"

37580 results found.

  1. Swift GRB 250818A: Global MASTER-Net observations report
  2. GRB 250818B: NOT optical observations
  3. GRB 250818A: Swift-XRT refined Analysis
  4. GRB 250818B: EP-FXT counterpart detection
  5. GRB 250818A: Swift-BAT refined analysis
  6. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  7. GRB 250818C: Fermi GBM Final Real-time Localization
  8. GRB 250818B: Keck redshift of the optical afterglow
  9. Fermi trigger No 776849714: Global MASTER-Net observations report
  10. GRB 250818B: KAIT optical observations
  11. GRB 250818A: Swift/UVOT Upper Limits
  12. GRB 250818A: Enhanced Swift-XRT position
  13. GRB 250813B: SVOM/ECLAIRs refined analysis
  14. GRB 250818A: Fermi GBM Observation
  15. GRB 250818B: SVOM/VT optical observation
  16. GRB 250814A: Further GRAWITA TNG NIR observations
  17. GRB 250818B: Swift-XRT afterglow detection
  18. GRB 250818B: GOTO optical counterpart candidate
  19. GRB 250818B: SVOM detection of a short burst
  20. GRB 250818A: Swift detection of a burst
  21. GRB 250818A: Fermi GBM Final Real-time Localization
  22. GRB 250816A: SVOM/GRM observation of a short burst
  23. Fermi GRB 250814B: Global MASTER-Net observations report
  24. GRB 250816A: Fermi GBM Final Real-time Localization
  25. GRB 250814A: Swift-BAT refined analysis
  26. GRB 250815A: Fermi GBM Final Localization
  27. GRB 250813B: Liverpool Telescope optical upper limits
  28. GRB 250814A: Further COLIBRÍ optical upper limit
  29. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  30. GRB 250814A: GRAWITA TNG NIR observations
  31. GRB 250812A: SVOM/VT optical continued observation
  32. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  33. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  34. GRB250814A: TRT optical upper limits
  35. GRB 250814B: SVOM/GRM observation
  36. GRB 250814C: SVOM/GRM observation of a short burst
  37. GRB 250813B: SVOM/GRM observation
  38. GRB 250814A: P200/WIRC observations of the afterglow candidate
  39. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  40. GRB 250814A: KAIT optical upper limit
  41. GRB 250814A: Swift-XRT refined Analysis
  42. GRB 240814A: Fermi GBM Observation
  43. GRB 250814A: Possible afterglow candidate from P200/WIRC
  44. GRB 250813B: Fermi GBM Observation
  45. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  46. Fermi trigger No 776818276: Global MASTER-Net observations report
  47. GRB 250814A: J-band upper limit from WINTER
  48. GRB 250813B: NOT observations of the optical afterglow
  49. GRB 250813B: SVOM/VT optical observations
  50. Subject GRB 250813B: SVOM/MXT refined analysis
  51. GRB 250814A: COLIBRÍ optical upper limit
  52. GRB 250814B: Fermi GBM Final Real-time Localization
  53. GRB 250813A: AstroSat CZTI detection
  54. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  55. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  56. GRB 250814A: DDOTI Optical Upper Limit
  57. GRB 250813B: EP-FXT counterpart detection
  58. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  59. GRB 250813B: Swift-XRT afterglow detection
  60. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  61. GRB 250814A: Fermi GBM Final Real-time Localization
  62. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 250813B: Ondrejov D50 fast decay
  64. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  65. GRB 250813B: Ondrejov D50 optical afterglow detection
  66. GRB 250813B: SVOM detection of a bright long burst
  67. EP250812a: Nickel optical upper limit
  68. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  69. GRB 250812A: NTT spectroscopic redshift z = 2.57
  70. GRB 250812A: Swift/UVOT Detection
  71. GRB 250813A: Fermi GBM Final Localization
  72. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 250812A: EP-FXT counterpart detection
  74. GRB 250812A: Swift ToO observations
  75. GRB 250807B: Swift-BAT refined analysis
  76. GRB 250812A: Kilonova-Catcher optical afterglow detection
  77. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  78. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. GRB 250812A: SVOM/VT optical afterglow confirmation
  80. GRB 250812A: Swift-XRT afterglow detection
  81. GRB 250812A: TRT likely optical counterpart detection
  82. GRB 250812A: SVOM detection of a faint long burst
  83. GRB 250809A: Swift-BAT refined analysis
  84. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  85. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  86. GRB 250807A: Swift-BAT refined analysis
  87. GRB 250809A: Swift/UVOT Detection
  88. Corrected Swift-XRT Refined Analysis of GRB 250809A
  89. GRB 250809A: Swift-XRT refined Analysis
  90. GRB 250807B: SVOM/VT optical observation
  91. GRB 250809A: LCOGT Optical Upper Limits
  92. GRB 250702B: Chandra X-ray Detection
  93. Fermi GRB 250808A: Global MASTER-Net observations report
  94. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  95. GRB 250808A: VLT X-shooter candidate counterpart
  96. GRB 250809A: Prompt enhanced Swift-XRT position
  97. GRB 250809A: Swift detection of a gamma ray burst
  98. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 250808A: Fermi GBM Observation
  100. GRB 250808A: Swift-XRT candidate counterpart detection

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