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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"

36200 results found.

  1. GRB 250812A: SVOM/ECLAIRs refined analysis
  2. GRB 250821A: Swift-BAT refined analysis
  3. GRB 250821A: VLT/FORS2 Optical Observation
  4. GRB 250821A: GECAM-B detection
  5. GRB 250821B: SVOM/GRM observation
  6. Fermi GRB 250821B: Global MASTER-Net observations report
  7. GRB 250821A: NOT z-band upper limit
  8. GRB 250821C: Fermi GBM Final Real-time Localization
  9. GRB 250821A: KAIT optical upper limit
  10. GRB 250821A: Swift-XRT refined Analysis
  11. Swift GRB 250821A: Global MASTER-Net observations report
  12. GRB 250821B: Fermi GBM Detection
  13. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  14. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  15. GRB 250821A: Enhanced Swift-XRT position
  16. GRB 250821A: Swift/UVOT Upper Limits
  17. GRB 250821A: LCOGT Optical Upper Limits
  18. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  19. GRB 250821A: Prompt enhanced Swift-XRT position
  20. GRB 250821A: Swift detection of a burst
  21. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  22. GRB 250819A: Insight-HXMT detection
  23. GRB 250818B: 10 GHz VLA detection
  24. GRB 250814A: Swift/UVOT Upper Limits
  25. GRB 250813B: Swift/UVOT Upper Limit
  26. IPN triangulation of GRB 250816A (short)
  27. IPN triangulation of GRB 250814C (short)
  28. IPN triangulation of GRB 250804B (short)
  29. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  30. GRB 250818B: Kilonova-Catcher optical afterglow detection
  31. GRB 250818B: Liverpool Telescope optical detections
  32. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  33. GRB 250818A: AstroSat CZTI detection
  34. GRB 250818B: Swift/UVOT Detection
  35. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  36. GRB 250820A: Fermi GBM Final Real-time Localization
  37. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  38. GRB 250818B: TRT Optical Observation
  39. Fermi GRB 250816A: Global MASTER-Net observations report
  40. GRB 250818B: SAO RAS optical observations
  41. Swift GRB 250818A: Global MASTER-Net observations report
  42. GRB 250818B: NOT optical observations
  43. GRB 250818A: Swift-XRT refined Analysis
  44. GRB 250818B: EP-FXT counterpart detection
  45. GRB 250818A: Swift-BAT refined analysis
  46. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  47. GRB 250818C: Fermi GBM Final Real-time Localization
  48. GRB 250818B: Keck redshift of the optical afterglow
  49. GRB 250818B: KAIT optical observations
  50. GRB 250818A: Swift/UVOT Upper Limits
  51. GRB 250818A: Enhanced Swift-XRT position
  52. GRB 250813B: SVOM/ECLAIRs refined analysis
  53. GRB 250818A: Fermi GBM Observation
  54. GRB 250818B: SVOM/VT optical observation
  55. GRB 250814A: Further GRAWITA TNG NIR observations
  56. GRB 250818B: Swift-XRT afterglow detection
  57. GRB 250818B: GOTO optical counterpart candidate
  58. GRB 250818B: SVOM detection of a short burst
  59. GRB 250818A: Swift detection of a burst
  60. GRB 250818A: Fermi GBM Final Real-time Localization
  61. GRB 250816A: SVOM/GRM observation of a short burst
  62. Fermi GRB 250814B: Global MASTER-Net observations report
  63. GRB 250816A: Fermi GBM Final Real-time Localization
  64. GRB 250814A: Swift-BAT refined analysis
  65. GRB 250815A: Fermi GBM Final Localization
  66. GRB 250813B: Liverpool Telescope optical upper limits
  67. GRB 250814A: Further COLIBRÍ optical upper limit
  68. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  69. GRB 250814A: GRAWITA TNG NIR observations
  70. GRB 250812A: SVOM/VT optical continued observation
  71. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  72. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  73. GRB250814A: TRT optical upper limits
  74. GRB 250814B: SVOM/GRM observation
  75. GRB 250814C: SVOM/GRM observation of a short burst
  76. GRB 250813B: SVOM/GRM observation
  77. GRB 250814A: P200/WIRC observations of the afterglow candidate
  78. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  79. GRB 250814A: KAIT optical upper limit
  80. GRB 250814A: Swift-XRT refined Analysis
  81. GRB 240814A: Fermi GBM Observation
  82. GRB 250814A: Possible afterglow candidate from P200/WIRC
  83. GRB 250813B: Fermi GBM Observation
  84. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  85. GRB 250814A: J-band upper limit from WINTER
  86. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 250813B: NOT observations of the optical afterglow
  88. GRB 250813B: SVOM/VT optical observations
  89. Subject GRB 250813B: SVOM/MXT refined analysis
  90. GRB 250814A: COLIBRÍ optical upper limit
  91. GRB 250814B: Fermi GBM Final Real-time Localization
  92. GRB 250813A: AstroSat CZTI detection
  93. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  94. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  95. GRB 250814A: DDOTI Optical Upper Limit
  96. GRB 250813B: EP-FXT counterpart detection
  97. GRB 250813B: Swift-XRT afterglow detection
  98. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  99. GRB 250814A: Fermi GBM Final Real-time Localization
  100. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations

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