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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"

27120 results found.

  1. EP250812a: Einstein Probe detection of an X-ray transient
  2. GRB 250812A: SVOM/VT optical afterglow confirmation
  3. GRB 250812A: TRT likely optical counterpart detection
  4. GRB 250812A: SVOM detection of a faint long burst
  5. GRB 250809A: Swift-BAT refined analysis
  6. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  7. GRB 250807A: Swift-BAT refined analysis
  8. GRB 250809A: Swift/UVOT Detection
  9. Corrected Swift-XRT Refined Analysis of GRB 250809A
  10. GRB 250809A: Swift-XRT refined Analysis
  11. GRB 250807B: SVOM/VT optical observation
  12. EP250807a: EP-FXT follow-up observation upper limit
  13. GRB 250809A: LCOGT Optical Upper Limits
  14. GRB 250702B: Chandra X-ray Detection
  15. EP250807a: Global MASTER-Net observations report
  16. Fermi GRB 250808A: Global MASTER-Net observations report
  17. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  18. GRB 250808A: VLT X-shooter candidate counterpart
  19. GRB 250809A: Swift detection of a gamma ray burst
  20. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. GRB 250808A: Fermi GBM Observation
  22. GRB 250808A: Swift-XRT candidate counterpart detection
  23. GRB 250807A: SVOM/VT optical continued observation
  24. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  25. GRB 250808A: SVOM detection of a long burst
  26. GRB 250808A: Fermi GBM Final Real-time Localization
  27. GRB 250807B: Swift/UVOT Detection
  28. GRB 250807B: Kilonova-Catcher optical afterglow detection
  29. GRB 250807A: Swift/UVOT Detection
  30. GRB 250807A: Swift-XRT refined Analysis
  31. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  32. GRB 250806A: SVOM/MXT refined analysis
  33. GRB 250806A: SVOM/ECLAIRs refined analysis
  34. EP250807a: NTT z-band optical upper limit
  35. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  36. GRB 250807A: SVOM/GRM observation
  37. Swift GRB250807.45: Global MASTER-Net observations report
  38. GRB 250807B: Swift-XRT refined Analysis
  39. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  40. GRB 250807B: NTT optical observations
  41. EP250807a: EP-WXT detection of a fast X-ray transient
  42. EP 250807.979: GOTO optical upper limit
  43. EP250807a: COLIBRÍ optical upper limit
  44. GRB 250807A: SVOM/VT optical observation
  45. EP250806a: Upper limit from Fermi-GBM Observations
  46. Swift GRB250807.65: Global MASTER-Net observations report
  47. GRB 250807B: Swift detection of a burst with an optical counterpart.
  48. GRB 250805A: Kilonova-Catcher optical upper limits
  49. EP250806a:SVOM/VT refined analysis
  50. GRB 250805A: Swift/UVOT Upper Limits
  51. GRB 250806A: Swift/UVOT U-band detection
  52. EP250806a: Liverpool telescope optical upper limit
  53. GRB 250807A: Swift detection of a burst with an optical counterpart
  54. IceCube Alert 250804.84: Global MASTER-Net observations report
  55. GRB 250806A: EP-FXT observation
  56. EP#01709198415/EP250806a: Swift-XRT observations
  57. EP250806a: Global MASTER-Net observations report
  58. EP250802a: EP-FXT follow-up observation
  59. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  60. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  61. EP250806a: SVOM /VT optical candidate
  62. GRB 250806A: J-band upper limit from WINTER
  63. GRB 250805A: Swift-BAT refined analysis
  64. GRB 250806A: SVOM/VT refined analysis
  65. GRB 250806A: Swift-XRT counterpart detection
  66. EP250806a: COLIBRÍ optical upper limit
  67. GRB 250806A: Kilonova-Catcher optical upper limits
  68. EP250806a: Einstein Probe detection of an X-ray transient
  69. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 250806A: SVOM/VT optical upper limit
  71. GRB 250806A: SVOM detection of a soft burst
  72. GRB 250805A: SVOM/VT optical counterpart
  73. GRB 250805A: Swift-XRT refined Analysis
  74. GRB 250804C: AstroSat CZTI detection of a long burst
  75. GRB 250805A: TRT optical upper limits
  76. GRB 250805A: Swift-XRT observations
  77. GRB 250805A: Swift detection of a burst
  78. Swift GRB250805.26: Global MASTER-Net observations report
  79. Fermi trigger No 776041355: Global MASTER-Net observations report
  80. GRB 250804B: SVOM/GRM observation of a short burst
  81. GRB 250804A: Fermi GBM Final Localization
  82. EP250730a: SVOM/VT optical upper limit
  83. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  84. EP250802a: Liverpool Telescope optical upper limits
  85. EP250802a: Global MASTER-Net observations report
  86. EP250802a: GROWTH-India Telescope optical upper limit
  87. EP250802a: Einstein Probe detection of an X-ray transient
  88. The EP-WXT trigger 01709198251 is likely a flaring star
  89. The EP-WXT trigger 01709198202 is likely a flaring star
  90. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  91. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  92. EP250711a: CrAO and Assy optical observations
  93. EP250730a: Global MASTER-Net observations report
  94. EP250730a: COLIBRÍ optical upper limit
  95. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  96. EP250730a: Einstein Probe detection of an X-ray transient
  97. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  98. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  99. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  100. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO

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