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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"

28300 results found.

  1. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  2. GRB 250814A: J-band upper limit from WINTER
  3. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 250813B: NOT observations of the optical afterglow
  5. GRB 250814A: COLIBRÍ optical upper limit
  6. GRB 250813A: AstroSat CZTI detection
  7. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  8. GRB 250814A: DDOTI Optical Upper Limit
  9. GRB 250813B: EP-FXT counterpart detection
  10. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  11. GRB 250813B: Swift-XRT afterglow detection
  12. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  13. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  14. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  15. GRB 250813B: SVOM detection of a bright long burst
  16. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  17. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  18. EP250812a: Nickel optical upper limit
  19. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  20. EP250812a: NOT, NTT, and GS observations
  21. GRB 250812A: Swift/UVOT Detection
  22. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  23. EP250812a: Liverpool Telescope upper limits
  24. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  25. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  26. GRB 250812A: EP-FXT counterpart detection
  27. GRB 250807B: Swift-BAT refined analysis
  28. EP 250812a: GOTO optical upper limit
  29. GRB 250812A: Kilonova-Catcher optical afterglow detection
  30. EP250812a: Swift-XRT counterpart detection
  31. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  32. EP250812a: Einstein Probe detection of an X-ray transient
  33. GRB 250812A: Swift-XRT afterglow detection
  34. GRB 250812A: TRT likely optical counterpart detection
  35. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 250809A: Swift-BAT refined analysis
  37. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  38. GRB 250807A: Swift-BAT refined analysis
  39. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  40. GRB 250809A: Swift/UVOT Detection
  41. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  42. Corrected Swift-XRT Refined Analysis of GRB 250809A
  43. GRB 250809A: Swift-XRT refined Analysis
  44. GRB 250809A: LCOGT Optical Upper Limits
  45. GRB 250808A: VLT X-shooter candidate counterpart
  46. GRB 250809A: Swift detection of a gamma ray burst
  47. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 250808A: Fermi GBM Observation
  49. GRB 250808A: Swift-XRT candidate counterpart detection
  50. GRB 250807B: Swift/UVOT Detection
  51. GRB 250807B: Kilonova-Catcher optical afterglow detection
  52. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 250807A: Swift/UVOT Detection
  54. GRB 250807A: Swift-XRT refined Analysis
  55. GRB 250806A: SVOM/MXT refined analysis
  56. EP250807a: NTT z-band optical upper limit
  57. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  58. GRB 250807A: SVOM/GRM observation
  59. GRB 250807A: AstroSat CZTI detection of bright long burst
  60. GRB 250807B: Swift-XRT refined Analysis
  61. EP250807a: EP-WXT detection of a fast X-ray transient
  62. EP 250807.979: GOTO optical upper limit
  63. EP250807a: COLIBRÍ optical upper limit
  64. EP250806a: Upper limit from Fermi-GBM Observations
  65. GRB 250807B: Enhanced Swift-XRT position
  66. GRB 250807A: Enhanced Swift-XRT position
  67. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 250807B: Swift detection of a burst with an optical counterpart.
  69. GRB 250805A: Kilonova-Catcher optical upper limits
  70. GRB 250805A: Swift/UVOT Upper Limits
  71. GRB 250806A: Swift/UVOT U-band detection
  72. EP250806a: Liverpool telescope optical upper limit
  73. GRB 250807A: Swift detection of a burst with an optical counterpart
  74. EP250802a: EP-FXT follow-up observation
  75. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  76. EP250806a: SVOM /VT optical candidate
  77. GRB 250806A: J-band upper limit from WINTER
  78. GRB 250805A: Swift-BAT refined analysis
  79. GRB 250806A: KAIT optical upper limit
  80. GRB 250806A: Swift-XRT counterpart detection
  81. EP250806a: COLIBRÍ optical upper limit
  82. GRB 250806A: Kilonova-Catcher optical upper limits
  83. EP250806a: Einstein Probe detection of an X-ray transient
  84. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. GRB 250806A: SVOM/VT optical upper limit
  86. GRB 250806A: SVOM detection of a soft burst
  87. GRB 250805A: SVOM/VT optical counterpart
  88. GRB 250805A: Swift-XRT refined Analysis
  89. GRB 250804B: Swift-XRT observations
  90. GRB 250805A: Enhanced Swift-XRT position
  91. GRB 250805A: TRT optical upper limits
  92. GRB 250805A: Swift-XRT observations
  93. GRB 250804B: SVOM/GRM observation of a short burst
  94. GRB 250804A: Fermi GBM Final Localization
  95. EP250802a: additional Liverpool Telescope upper limits
  96. EP250730a: SVOM/VT optical upper limit
  97. EP250802a: Liverpool Telescope optical upper limits
  98. EP250802a: Global MASTER-Net observations report
  99. EP250802a: GROWTH-India Telescope optical upper limit
  100. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization

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