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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"

20397 results found.

  1. GRB 250809A: LCOGT Optical Upper Limits
  2. GRB 250808A: VLT X-shooter candidate counterpart
  3. GRB 250809A: Swift detection of a gamma ray burst
  4. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. Konus-Wind detection of GRB 250807A
  6. GRB 250807B: Swift/UVOT Detection
  7. GRB 250807B: Kilonova-Catcher optical afterglow detection
  8. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 250807A: Swift/UVOT Detection
  10. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  11. GRB 250806A: SVOM/ECLAIRs refined analysis
  12. EP250807a: NTT z-band optical upper limit
  13. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  14. GRB 250807A: SVOM/GRM observation
  15. GRB 250807A: AstroSat CZTI detection of bright long burst
  16. EP250807a: EP-WXT detection of a fast X-ray transient
  17. EP 250807.979: GOTO optical upper limit
  18. EP250807a: COLIBRÍ optical upper limit
  19. GRB 250807B: Enhanced Swift-XRT position
  20. GRB 250807A: Enhanced Swift-XRT position
  21. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 250807B: Swift detection of a burst with an optical counterpart.
  23. GRB 250805A: Kilonova-Catcher optical upper limits
  24. GRB 250805A: Swift/UVOT Upper Limits
  25. GRB 250806A: Swift/UVOT U-band detection
  26. EP250806a: Liverpool telescope optical upper limit
  27. GRB 250807A: Swift detection of a burst with an optical counterpart
  28. GRB 250806A: EP-FXT observation
  29. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  30. EP250806a: SVOM /VT optical candidate
  31. GRB 250806A: J-band upper limit from WINTER
  32. GRB 250806A: KAIT optical upper limit
  33. EP250806a: COLIBRÍ optical upper limit
  34. GRB 250806A: Kilonova-Catcher optical upper limits
  35. EP250806a: Einstein Probe detection of an X-ray transient
  36. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 250806A: SVOM/VT optical upper limit
  38. GRB 250806A: SVOM detection of a soft burst
  39. GRB 250805A: SVOM/VT optical counterpart
  40. GRB 250805A: Enhanced Swift-XRT position
  41. GRB 250805A: TRT optical upper limits
  42. GRB 250805A: Swift-XRT observations
  43. GRB 250804B: SVOM/GRM observation of a short burst
  44. EP250802a: additional Liverpool Telescope upper limits
  45. EP250730a: SVOM/VT optical upper limit
  46. EP250802a: Liverpool Telescope optical upper limits
  47. EP250802a: GROWTH-India Telescope optical upper limit
  48. EP250802a: Einstein Probe detection of an X-ray transient
  49. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  51. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  52. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  53. EP250711a: CrAO and Assy optical observations
  54. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  55. EP250730a: COLIBRÍ optical upper limit
  56. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  57. EP250730a: Einstein Probe detection of an X-ray transient
  58. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  59. GRB 250725A: PRIME near-infrared observations
  60. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  61. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  62. GRB 250727A: SVOM/ECLAIRs refined analysis
  63. GRB 250728A: COLIBRÍ optical upper limit
  64. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  67. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  68. GRB 250725A: SVOM/GRM observation
  69. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  70. GRB 250725A: Swift/UVOT Upper Limits
  71. GRB 250725A: SVOM/VT optical candidate
  72. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  74. GRB 250725A: Enhanced Swift-XRT position
  75. GRB 250725A: Swift detection of a burst
  76. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  77. SVOM J195836+32283 is not a real source
  78. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  79. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  80. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  81. GRB 250721A: Swift-XRT observations
  82. GRB 250713A : SVOM/ECLAIRs refined analysis
  83. GRB 250717B: SVOM/GRM observation
  84. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  85. GRB 250717B: COLIBRÍ optical upper limit
  86. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  87. GRB 270713A: Kitab and AbAO Optical Observations
  88. Konus-Wind detection of GRB 250716A
  89. GRB 250716A: Swift-XRT afterglow detection
  90. GRB 250714A: SVOM/GRM observation
  91. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  92. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  93. GRB 250713A: Mephisto optical upper limits
  94. GRB 250713A: SVOM/VT optical upper limit
  95. GRB 250713A: NOT optical upper limits
  96. GRB 250713A: OHP/T193 upper limit
  97. GRB 250713A: SVOM/C-GFT upper limit
  98. GRB 250706B/C: 7DT Follow-up Observations
  99. GRB 250713A: EP-FXT counterpart detection
  100. EP250711a: COLIBRÍ continuous optical observations

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