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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"

42499 results found.

  1. GRB 250907A: GECAM-B detection
  2. GRB 250905A: Swift-BAT refined analysis
  3. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  4. GRB 250903A: Swift-XRT afterglow detection
  5. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  6. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  7. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  8. EP250905a: Liverpool Telescope i-band upper limits
  9. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  10. EP250905b: EP-FXT follow-up observation
  11. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  12. EP250905a: Liverpool Telescope observations
  13. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP250905b: Global MASTER-Net observations report
  15. EP250905b: EP-WXT detection of a fast X-ray transient
  16. EP250905a: FTW one optical and multiple NIR counterpart candidates
  17. GRB 250905A: Swift-XRT refined Analysis
  18. EP250905a: JinShan likely optical counterpart detection
  19. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 250904A: Swift-BAT refined analysis
  21. IceCube Alert 250905.84: Global MASTER-Net observations report
  22. GRB 250905A: Swift/UVOT Upper Limits
  23. EP250905a: Global MASTER-Net observations report
  24. GRB 250901A - SVOM/ECLAIRs refined analysis
  25. EP250905a: Einstein Probe detection of an X-ray transient
  26. GRB 250905B: Fermi GBM Final Localization
  27. GRB250904A: Liverpool Telescope upper limits
  28. GRB 250905A: Enhanced Swift-XRT position
  29. GRB 250904A: Swift/UVOT Detection
  30. GRB 250903A: Swift/UVOT detection
  31. GRB 250904A: Swift-XRT refined Analysis
  32. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  33. EP detected a brightening of LMXB 1ES 1735-26.9
  34. GRB 250905A: KAIT optical upper limit
  35. GRB 250905A: Swift detection of a burst
  36. Swift GRB250905.09: Global MASTER-Net observations report
  37. Swift GRB 250904A: Global MASTER-Net observations report
  38. GRB 250904A: Enhanced Swift-XRT position
  39. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 250904A: TRT optical counterpart detection
  41. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  42. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 250904A: Prompt enhanced Swift-XRT position
  44. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  45. GRB 250904A: Swift detection of a burst
  46. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  47. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  48. GRB 250903A: Swift-XRT observations
  49. EP250903a: Swift-XRT observations
  50. EP#01709201209: Swift-XRT observations
  51. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  52. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  53. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  54. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  55. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  56. The EP-WXT trigger 01709201209 is likely a flaring star
  57. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  58. GRB 250903A: EP-FXT counterpart detection
  59. GRB 250902A: GECAM-B detection
  60. GRB 250903A: LCO optical observation
  61. GRB 250903A: LCO optical afterglow detection
  62. GRB 250903A: SVOM/VT optical confirmation with VHF data
  63. EP250903a: SVOM/VT optical confirmation
  64. EP250901a: Mondy, Assy and SAO RAS optical limits
  65. Subject GRB 250903A: SVOM/MXT afterglow detection
  66. EP250903a: LCO candidate counterpart discovery
  67. GRB 250903A: TRT optical counterpart detection
  68. GRB 250902B: AstroSat CZTI detection
  69. GRB 250903A: SVOM detection of a burst
  70. EP250903a: Global MASTER-Net observations report
  71. EP250903a: TRT optical observations
  72. EP250903a: Einstein Probe detection of an X-ray transient
  73. EP 250827B: Detection of supernova counterpart by LCO.
  74. EP/WXT01709201159: GOTO optical follow-up
  75. EP250827b / AT 2025wkm: TRT optical observations
  76. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  77. EP250827b: continued Liverpool Telescope observations
  78. GRB 250902B: SVOM/GRM observation
  79. EP250827b: SVOM/VT observation of AT 2025wkm
  80. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  81. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  82. Fermi GRB 250902B: Global MASTER-Net observations report
  83. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  84. GRB 250902A: Fermi GBM Detection
  85. GRB 250901A: Swift/UVOT Upper Limit
  86. GRB 250902B: Fermi GBM Final Real-time Localization
  87. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 250830B: Swift-XRT afterglow detection
  89. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  90. EP250827b: Liverpool Telescope observations
  91. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  92. GRB 250902A: SVOM/GRM observation
  93. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  94. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  95. GRB 250901A: EP-FXT follow-up observation
  96. GRB 250901A: NOT optical observations
  97. GRB 250902A: Fermi GBM Final Real-time Localization
  98. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 250901A: SVOM/VT optical afterglow with VHF data
  100. GRB 250901A: Swift-XRT afterglow detection

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