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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"

45692 results found.

  1. GRB 250905A: Swift detection of a burst
  2. Swift GRB250905.09: Global MASTER-Net observations report
  3. Swift GRB 250904A: Global MASTER-Net observations report
  4. GRB 250904A: Enhanced Swift-XRT position
  5. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 250904A: TRT optical counterpart detection
  7. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  8. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  9. GRB 250904A: Prompt enhanced Swift-XRT position
  10. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  11. GRB 250904A: Swift detection of a burst
  12. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  13. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  14. GRB 250902A: VZLUSAT-2 detection
  15. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  16. GRB 250903A: Swift-XRT observations
  17. EP250903a: Swift-XRT observations
  18. EP#01709201209: Swift-XRT observations
  19. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  20. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  21. GRB 250830C: VZLUSAT-2 detection
  22. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  23. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  24. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  25. The EP-WXT trigger 01709201209 is likely a flaring star
  26. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  27. GRB 250903A: EP-FXT counterpart detection
  28. GRB 250902A: GECAM-B detection
  29. GRB 250903A: LCO optical observation
  30. GRB 250903A: LCO optical afterglow detection
  31. GRB 250903A: SVOM/VT optical confirmation with VHF data
  32. EP250903a: SVOM/VT optical confirmation
  33. EP250901a: Mondy, Assy and SAO RAS optical limits
  34. Subject GRB 250903A: SVOM/MXT afterglow detection
  35. EP250903a: LCO candidate counterpart discovery
  36. GRB 250903A: TRT optical counterpart detection
  37. GRB 250902B: AstroSat CZTI detection
  38. GRB 250903A: SVOM detection of a burst
  39. EP250903a: Global MASTER-Net observations report
  40. EP250903a: TRT optical observations
  41. EP250903a: Einstein Probe detection of an X-ray transient
  42. EP 250827B: Detection of supernova counterpart by LCO.
  43. EP/WXT01709201159: GOTO optical follow-up
  44. EP250827b / AT 2025wkm: TRT optical observations
  45. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  46. EP250827b: continued Liverpool Telescope observations
  47. GRB 250902B: SVOM/GRM observation
  48. EP250827b: SVOM/VT observation of AT 2025wkm
  49. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  50. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  51. Fermi GRB 250902B: Global MASTER-Net observations report
  52. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  53. GRB 250902A: Fermi GBM Detection
  54. GRB 250901A: Swift/UVOT Upper Limit
  55. GRB 250902B: Fermi GBM Final Real-time Localization
  56. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 250830B: Swift-XRT afterglow detection
  58. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  59. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  60. EP250827b: Liverpool Telescope observations
  61. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  62. GRB 250902A: SVOM/GRM observation
  63. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  64. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  65. GRB 250901A: EP-FXT follow-up observation
  66. GRB 250901A: NOT optical observations
  67. GRB 250902A: Fermi GBM Final Real-time Localization
  68. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 250901A: SVOM/VT optical afterglow with VHF data
  70. GRB 250901A: Swift-XRT afterglow detection
  71. EP250901a: Swift-XRT observations
  72. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  73. GRB 250901A: LCO optical upper limit
  74. EP250827b: Swift observations of AT 2025wkm
  75. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  76. EP250827b: Gemini Spectroscopy of AT 2025wkm
  77. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  78. EP250831a: NOT optical observations and tentative afterglow candidate
  79. EP250827b: FTW Observations of AT 2025wkm
  80. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  81. GRB 250901A: SVOM detection of a burst
  82. GRB 250831B: SVOM/GRM observation
  83. GRB 250830C: Insight-HXMT detection
  84. EP250901a: Mephisto optical upper limits
  85. GRB 250830C: GECAM-B detection
  86. EP250901a: Global MASTER-Net observations report
  87. GRB 250830C: AstroSat CZTI detection of a long burst
  88. EP250901a: Einstein Probe detection of an X-ray transient
  89. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  90. EP250831a: EP-FXT follow-up observation
  91. EP250831a: Swift-XRT observations
  92. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  93. IceCube Alert 250831.75: Global MASTER-Net observations report
  94. EP250831a: Global MASTER-Net observations report
  95. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  96. EP250831a: EP-WXT detection of a fast X-ray transient
  97. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  98. GRB 250831A: Swift-XRT counterpart detection
  99. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. GRB 250831A: SVOM/VT upper limit with VHF data

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