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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"

27112 results found.

  1. Corrected Swift-XRT Refined Analysis of GRB 250809A
  2. GRB 250809A: Swift-XRT refined Analysis
  3. GRB 250807B: SVOM/VT optical observation
  4. EP250807a: EP-FXT follow-up observation upper limit
  5. GRB 250809A: LCOGT Optical Upper Limits
  6. GRB 250702B: Chandra X-ray Detection
  7. EP250807a: Global MASTER-Net observations report
  8. Fermi GRB 250808A: Global MASTER-Net observations report
  9. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  10. GRB 250808A: VLT X-shooter candidate counterpart
  11. GRB 250809A: Swift detection of a gamma ray burst
  12. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB 250808A: Fermi GBM Observation
  14. GRB 250808A: Swift-XRT candidate counterpart detection
  15. GRB 250807A: SVOM/VT optical continued observation
  16. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  17. GRB 250808A: SVOM detection of a long burst
  18. GRB 250808A: Fermi GBM Final Real-time Localization
  19. GRB 250807B: Swift/UVOT Detection
  20. GRB 250807B: Kilonova-Catcher optical afterglow detection
  21. GRB 250807A: Swift/UVOT Detection
  22. GRB 250807A: Swift-XRT refined Analysis
  23. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  24. GRB 250806A: SVOM/MXT refined analysis
  25. GRB 250806A: SVOM/ECLAIRs refined analysis
  26. EP250807a: NTT z-band optical upper limit
  27. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  28. GRB 250807A: SVOM/GRM observation
  29. Swift GRB250807.45: Global MASTER-Net observations report
  30. GRB 250807B: Swift-XRT refined Analysis
  31. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  32. GRB 250807B: NTT optical observations
  33. EP250807a: EP-WXT detection of a fast X-ray transient
  34. EP 250807.979: GOTO optical upper limit
  35. EP250807a: COLIBRÍ optical upper limit
  36. GRB 250807A: SVOM/VT optical observation
  37. EP250806a: Upper limit from Fermi-GBM Observations
  38. Swift GRB250807.65: Global MASTER-Net observations report
  39. GRB 250807B: Swift detection of a burst with an optical counterpart.
  40. GRB 250805A: Kilonova-Catcher optical upper limits
  41. EP250806a:SVOM/VT refined analysis
  42. GRB 250805A: Swift/UVOT Upper Limits
  43. GRB 250806A: Swift/UVOT U-band detection
  44. EP250806a: Liverpool telescope optical upper limit
  45. GRB 250807A: Swift detection of a burst with an optical counterpart
  46. IceCube Alert 250804.84: Global MASTER-Net observations report
  47. GRB 250806A: EP-FXT observation
  48. EP#01709198415/EP250806a: Swift-XRT observations
  49. EP250806a: Global MASTER-Net observations report
  50. EP250802a: EP-FXT follow-up observation
  51. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  52. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  53. EP250806a: SVOM /VT optical candidate
  54. GRB 250806A: J-band upper limit from WINTER
  55. GRB 250805A: Swift-BAT refined analysis
  56. GRB 250806A: SVOM/VT refined analysis
  57. GRB 250806A: Swift-XRT counterpart detection
  58. EP250806a: COLIBRÍ optical upper limit
  59. GRB 250806A: Kilonova-Catcher optical upper limits
  60. EP250806a: Einstein Probe detection of an X-ray transient
  61. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 250806A: SVOM/VT optical upper limit
  63. GRB 250806A: SVOM detection of a soft burst
  64. GRB 250805A: SVOM/VT optical counterpart
  65. GRB 250805A: Swift-XRT refined Analysis
  66. GRB 250804C: AstroSat CZTI detection of a long burst
  67. GRB 250805A: TRT optical upper limits
  68. GRB 250805A: Swift-XRT observations
  69. GRB 250805A: Swift detection of a burst
  70. Swift GRB250805.26: Global MASTER-Net observations report
  71. Fermi trigger No 776041355: Global MASTER-Net observations report
  72. GRB 250804B: SVOM/GRM observation of a short burst
  73. GRB 250804A: Fermi GBM Final Localization
  74. EP250730a: SVOM/VT optical upper limit
  75. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  76. EP250802a: Liverpool Telescope optical upper limits
  77. EP250802a: Global MASTER-Net observations report
  78. EP250802a: GROWTH-India Telescope optical upper limit
  79. EP250802a: Einstein Probe detection of an X-ray transient
  80. The EP-WXT trigger 01709198251 is likely a flaring star
  81. The EP-WXT trigger 01709198202 is likely a flaring star
  82. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  83. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  84. EP250711a: CrAO and Assy optical observations
  85. EP250730a: Global MASTER-Net observations report
  86. EP250730a: COLIBRÍ optical upper limit
  87. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  88. EP250730a: Einstein Probe detection of an X-ray transient
  89. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  90. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  92. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  94. GRB 250727A: EP-FXT follow-up observation
  95. GRB 250727A: SVOM/ECLAIRs refined analysis
  96. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  97. GRB 250728A: COLIBRÍ optical upper limit
  98. GRB 250728A: Fermi GBM Observation
  99. Fermi trigger No 775387550: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm

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