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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"

32693 results found.

  1. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  2. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  3. EP250911a: COLIBRÍ optical observations
  4. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  5. Fermi GRB 250910B: Global MASTER-Net observations report
  6. EP250911a: LCO optical counterpart discovery
  7. EP250910a: Global MASTER-Net observations report
  8. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  9. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  10. GRB 250903A: SVOM/ECLAIRs refined analysis
  11. GRB 250911A: COLIBRÍ optical counterpart candidate
  12. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  13. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  14. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  15. GRB 250910A: SVOM/VT optical upper limit
  16. EP250908C: GROND observation of the fading optical counterpart
  17. GRB 250910A: LCO optical upper limit
  18. GRB 250909A: AstroSat CZTI detection
  19. GRB 250910A: SVOM/MXT possible afterglow detection
  20. GRB 250702B: Late time Chandra observations
  21. EP250908b/EP#01709240653: Swift/UVOT Detection
  22. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  23. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  24. EP250908c: SVOM/VT optical observation
  25. EP250908c: VLT/FORS2 optical counterpart identification
  26. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  27. EP250908b: SVOM/VT optical candidate
  28. EP250908c: Global MASTER-Net observations report
  29. Fermi GRB 250909A: Global MASTER-Net observations report
  30. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  31. GRB 250905A: Swift-BAT refined analysis
  32. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  33. GRB 250903A: Swift-XRT afterglow detection
  34. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  35. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  36. EP250905a: Liverpool Telescope i-band upper limits
  37. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  38. EP250905b: EP-FXT follow-up observation
  39. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  40. EP250905a: Liverpool Telescope observations
  41. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  42. EP250905b: Global MASTER-Net observations report
  43. EP250905a: FTW one optical and multiple NIR counterpart candidates
  44. EP250905a: JinShan likely optical counterpart detection
  45. GRB 250904A: Swift-BAT refined analysis
  46. GRB 250905A: Swift/UVOT Upper Limits
  47. EP250905a: Global MASTER-Net observations report
  48. GRB 250901A - SVOM/ECLAIRs refined analysis
  49. GRB250904A: Liverpool Telescope upper limits
  50. GRB 250904A: Swift/UVOT Detection
  51. GRB 250903A: Swift/UVOT detection
  52. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  53. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  54. GRB 250905A: KAIT optical upper limit
  55. Swift GRB 250904A: Global MASTER-Net observations report
  56. GRB 250904A: TRT optical counterpart detection
  57. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  58. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  59. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  60. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  61. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  62. GRB 250902A: VZLUSAT-2 detection
  63. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  64. GRB 250903A: Swift-XRT observations
  65. EP250903a: Swift-XRT observations
  66. EP#01709201209: Swift-XRT observations
  67. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  68. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  69. GRB 250830C: VZLUSAT-2 detection
  70. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  71. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  72. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  73. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  74. GRB 250903A: EP-FXT counterpart detection
  75. GRB 250902A: GECAM-B detection
  76. GRB 250903A: LCO optical observation
  77. GRB 250903A: LCO optical afterglow detection
  78. GRB 250903A: SVOM/VT optical confirmation with VHF data
  79. EP250903a: SVOM/VT optical confirmation
  80. EP250901a: Mondy, Assy and SAO RAS optical limits
  81. Subject GRB 250903A: SVOM/MXT afterglow detection
  82. EP250903a: LCO candidate counterpart discovery
  83. GRB 250903A: TRT optical counterpart detection
  84. GRB 250902B: AstroSat CZTI detection
  85. EP250903a: Global MASTER-Net observations report
  86. EP250903a: TRT optical observations
  87. EP250903a: Einstein Probe detection of an X-ray transient
  88. EP 250827B: Detection of supernova counterpart by LCO.
  89. EP250827b / AT 2025wkm: TRT optical observations
  90. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  91. EP250827b: continued Liverpool Telescope observations
  92. GRB 250902B: SVOM/GRM observation
  93. EP250827b: SVOM/VT observation of AT 2025wkm
  94. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  95. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  96. Fermi GRB 250902B: Global MASTER-Net observations report
  97. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  98. GRB 250902A: Fermi GBM Detection
  99. GRB 250901A: Swift/UVOT Upper Limit
  100. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube

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