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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"

28276 results found.

  1. GRB 250911A: Swift-BAT refined analysis
  2. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  3. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 250910B: SVOM/GRM observation
  5. EP250911a: SVOM/VT optical observation
  6. GRB 250911A: MASTER optical counterpart observations
  7. EP250911a: SAO RAS optical observations
  8. GRB 250911A: Swift-XRT refined Analysis
  9. EP250911a: Swift-XRT observations
  10. EP250911a: Optical detection with Kinder observations
  11. GRB 250911A: Swift/UVOT Detection
  12. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  13. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  14. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  15. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  16. EP250911a: COLIBRÍ optical observations
  17. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  18. EP250911a: LCO optical counterpart discovery
  19. EP250911a: Einstein Probe detection of an X-ray transient
  20. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  21. GRB 250903A: SVOM/ECLAIRs refined analysis
  22. GRB 250911A: Enhanced Swift-XRT position
  23. GRB 250911A: Swift-XRT observations
  24. GRB 250911A: COLIBRÍ optical counterpart candidate
  25. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  26. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  27. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  28. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  29. GRB 250910A: SVOM/VT optical upper limit
  30. GRB 250910A: LCO optical upper limit
  31. EP250908b/EP#01709240653: Swift/UVOT Detection
  32. EP#01709240653: Swift-XRT observations
  33. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  34. EP250908c: SVOM/VT optical observation
  35. EP250908c: VLT/FORS2 optical counterpart identification
  36. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  37. EP250908b: SVOM/VT optical candidate
  38. Fermi GRB 250909A: Global MASTER-Net observations report
  39. EP250908c: Einstein Probe detection of an X-ray transient
  40. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  41. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  42. GRB 250907A: GECAM-B detection
  43. GRB 250905A: Swift-BAT refined analysis
  44. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  45. GRB 250903A: Swift-XRT afterglow detection
  46. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  47. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  48. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  49. EP250905a: Liverpool Telescope i-band upper limits
  50. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  51. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  52. EP250905a: Liverpool Telescope observations
  53. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP250905b: EP-WXT detection of a fast X-ray transient
  55. GRB 250905A: Swift-XRT refined Analysis
  56. EP250905a: JinShan likely optical counterpart detection
  57. GRB 250904A: Swift-BAT refined analysis
  58. GRB 250905A: Swift/UVOT Upper Limits
  59. GRB 250901A - SVOM/ECLAIRs refined analysis
  60. EP250905a: Einstein Probe detection of an X-ray transient
  61. GRB250904A: Liverpool Telescope upper limits
  62. GRB 250905A: Enhanced Swift-XRT position
  63. GRB 250904A: Swift/UVOT Detection
  64. GRB 250903A: Swift/UVOT detection
  65. GRB 250904A: Swift-XRT refined Analysis
  66. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  67. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  68. EP detected a brightening of LMXB 1ES 1735-26.9
  69. GRB 250905A: KAIT optical upper limit
  70. GRB 250905A: Swift detection of a burst
  71. GRB 250904A: Enhanced Swift-XRT position
  72. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 250904A: TRT optical counterpart detection
  74. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  75. GRB 250904A: Swift detection of a burst
  76. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  77. GRB 250902A: VZLUSAT-2 detection
  78. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  79. GRB 250903A: Swift-XRT observations
  80. EP250903a: Swift-XRT observations
  81. EP#01709201209: Swift-XRT observations
  82. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  83. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  84. GRB 250830C: VZLUSAT-2 detection
  85. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  86. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  88. GRB 250903A: EP-FXT counterpart detection
  89. GRB 250902A: GECAM-B detection
  90. GRB 250903A: LCO optical observation
  91. GRB 250903A: LCO optical afterglow detection
  92. GRB 250903A: SVOM/VT optical confirmation with VHF data
  93. EP250901a: Mondy, Assy and SAO RAS optical limits
  94. EP250903a: LCO candidate counterpart discovery
  95. GRB 250903A: TRT optical counterpart detection
  96. EP250903a: TRT optical observations
  97. EP250903a: Einstein Probe detection of an X-ray transient
  98. EP 250827B: Detection of supernova counterpart by LCO.
  99. GRB 250902B: SVOM/GRM observation
  100. EP250827b: SVOM/VT observation of AT 2025wkm

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