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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23610 results found.

  1. GRB 250920C: GOTO optical counterpart candidate
  2. Konus-Wind detection of GRB 250919A
  3. GRB 250920C: Swift detection of a burst
  4. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  5. GRB 250919A / EP250919a: Insight-HXMT detection
  6. GRB 250920A: AstroSat CZTI detection
  7. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  8. GRB 250919A: Glowbug gamma-ray detection
  9. GRB 250919A: Fermi GBM Observation
  10. GRB 250919A: Swift-XRT afterglow detection
  11. GRB 250916A: KAIT optical observations
  12. GRB 250916A: further SAO RAS optical observations
  13. GRB 250917B: Swift-BAT refined analysis
  14. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  15. GRB 250917B: Swift/UVOT Upper Limits
  16. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  17. GRB 250916A: Swift-XRT observations
  18. GRB 250916A: MAO/AZT-22 optical observations
  19. GRB 250916A: SAO RAS optical observations
  20. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  21. GRB 250916A: Glowbug gamma-ray detection
  22. GRB250917B: WFST optical observations
  23. GRB 250917B: Swift-XRT observations
  24. GRB 250916A: GOTO optical counterpart candidate
  25. GRB 250916A: AstroSat CZTI detection of a bright long burst
  26. EP250916a: Einstein Probe detection of an X-ray transient
  27. EP250827b: VLA Observations
  28. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  29. GRB 250912A: Swift-XRT observations
  30. GRB250912A: VLT/HAWK-I follow-up observations
  31. GRB 250912A: VLT observations
  32. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  33. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  34. EP250911a: Upper limit from Fermi-GBM Observations
  35. GRB 250911A: Swift-BAT refined analysis
  36. EP250911a: SAO RAS optical observations
  37. EP250911a: Swift-XRT observations
  38. EP250911a: Optical detection with Kinder observations
  39. GRB 250911A: Swift/UVOT Detection
  40. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  41. GRB 250909B: Insight-HXMT detection
  42. GRB 250909B: SVOM/GRM observation
  43. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  44. EP250911a: COLIBRÍ optical observations
  45. EP250911a: LCO optical counterpart discovery
  46. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  47. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  48. GRB 250911A: Enhanced Swift-XRT position
  49. GRB 250911A: Swift-XRT observations
  50. GRB 250911A: COLIBRÍ optical counterpart candidate
  51. GRB 250911A: Swift detection of a burst
  52. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  53. GRB 250909B: AstroSat CZTI detection of a long burst
  54. GRB 250909A: AstroSat CZTI detection
  55. GRB 250910A: SVOM/MXT possible afterglow detection
  56. GRB 250702B: Late time Chandra observations
  57. EP250908b/EP#01709240653: Swift/UVOT Detection
  58. EP#01709240653: Swift-XRT observations
  59. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  60. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  61. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  62. EP250908c: VLT/FORS2 optical counterpart identification
  63. EP250908c: Einstein Probe detection of an X-ray transient
  64. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  65. GRB 250905A: Swift-BAT refined analysis
  66. GRB 250903A: Swift-XRT afterglow detection
  67. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  68. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  69. GRB 250905A: Swift-XRT refined Analysis
  70. GRB 250904A: Swift-BAT refined analysis
  71. GRB 250905A: KAIT optical upper limit
  72. GRB 250905A: Swift detection of a burst
  73. Swift GRB250905.09: Global MASTER-Net observations report
  74. GRB 250904A: TRT optical counterpart detection
  75. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  76. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  77. GRB 250904A: Swift detection of a burst
  78. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  79. GRB 250902A: VZLUSAT-2 detection
  80. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  81. GRB 250903A: Swift-XRT observations
  82. EP250903a: Swift-XRT observations
  83. EP#01709201209: Swift-XRT observations
  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. The EP-WXT trigger 01709201209 is likely a flaring star
  88. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  89. GRB 250903A: EP-FXT counterpart detection
  90. GRB 250903A: LCO optical afterglow detection
  91. EP250901a: Mondy, Assy and SAO RAS optical limits
  92. Subject GRB 250903A: SVOM/MXT afterglow detection
  93. EP250903a: LCO candidate counterpart discovery
  94. GRB 250903A: TRT optical counterpart detection
  95. GRB 250902B: AstroSat CZTI detection
  96. EP250903a: TRT optical observations
  97. EP 250827B: Detection of supernova counterpart by LCO.
  98. EP/WXT01709201159: GOTO optical follow-up
  99. EP250827b / AT 2025wkm: TRT optical observations
  100. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova

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