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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

45653 results found.

  1. GRB 250909B: AstroSat CZTI detection of a long burst
  2. GRB 250910A: SVOM/VT optical upper limit
  3. EP250908C: GROND observation of the fading optical counterpart
  4. GRB 250910A: LCO optical upper limit
  5. GRB 250909A: AstroSat CZTI detection
  6. GRB 250910A: SVOM/MXT possible afterglow detection
  7. GRB 250910A: SVOM detection of a faint burst
  8. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  9. GRB 250702B: Late time Chandra observations
  10. EP250908b/EP#01709240653: Swift/UVOT Detection
  11. EP#01709240653: Swift-XRT observations
  12. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  13. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  14. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  15. EP250908c: SVOM/VT optical observation
  16. EP250908c: VLT/FORS2 optical counterpart identification
  17. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  18. EP250908b: SVOM/VT optical candidate
  19. The EP-WXT trigger EP250908a/01709240652 is not a real source
  20. EP250908c: Global MASTER-Net observations report
  21. Fermi GRB 250909A: Global MASTER-Net observations report
  22. EP250908c: Einstein Probe detection of an X-ray transient
  23. GRB 250909A: Fermi GBM Final Real-time Localization
  24. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  25. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  26. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  27. GRB 250907A: GECAM-B detection
  28. GRB 250905A: Swift-BAT refined analysis
  29. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  30. GRB 250903A: Swift-XRT afterglow detection
  31. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  32. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  33. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  34. EP250905a: Liverpool Telescope i-band upper limits
  35. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  36. EP250905b: EP-FXT follow-up observation
  37. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  38. EP250905a: Liverpool Telescope observations
  39. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  40. EP250905b: Global MASTER-Net observations report
  41. EP250905b: EP-WXT detection of a fast X-ray transient
  42. EP250905a: FTW one optical and multiple NIR counterpart candidates
  43. GRB 250905A: Swift-XRT refined Analysis
  44. EP250905a: JinShan likely optical counterpart detection
  45. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 250904A: Swift-BAT refined analysis
  47. IceCube Alert 250905.84: Global MASTER-Net observations report
  48. GRB 250905A: Swift/UVOT Upper Limits
  49. EP250905a: Global MASTER-Net observations report
  50. GRB 250901A - SVOM/ECLAIRs refined analysis
  51. EP250905a: Einstein Probe detection of an X-ray transient
  52. GRB 250905B: Fermi GBM Final Localization
  53. GRB250904A: Liverpool Telescope upper limits
  54. GRB 250905A: Enhanced Swift-XRT position
  55. GRB 250904A: Swift/UVOT Detection
  56. GRB 250903A: Swift/UVOT detection
  57. GRB 250904A: Swift-XRT refined Analysis
  58. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  59. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  60. EP detected a brightening of LMXB 1ES 1735-26.9
  61. GRB 250905A: KAIT optical upper limit
  62. GRB 250905A: Swift detection of a burst
  63. Swift GRB250905.09: Global MASTER-Net observations report
  64. Swift GRB 250904A: Global MASTER-Net observations report
  65. GRB 250904A: Enhanced Swift-XRT position
  66. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 250904A: TRT optical counterpart detection
  68. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  69. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  70. GRB 250904A: Prompt enhanced Swift-XRT position
  71. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  72. GRB 250904A: Swift detection of a burst
  73. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  74. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  75. GRB 250902A: VZLUSAT-2 detection
  76. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  77. GRB 250903A: Swift-XRT observations
  78. EP250903a: Swift-XRT observations
  79. EP#01709201209: Swift-XRT observations
  80. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  81. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  82. GRB 250830C: VZLUSAT-2 detection
  83. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  84. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  85. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  86. The EP-WXT trigger 01709201209 is likely a flaring star
  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. EP250903a: SVOM/VT optical confirmation
  94. EP250901a: Mondy, Assy and SAO RAS optical limits
  95. Subject GRB 250903A: SVOM/MXT afterglow detection
  96. EP250903a: LCO candidate counterpart discovery
  97. GRB 250903A: TRT optical counterpart detection
  98. GRB 250902B: AstroSat CZTI detection
  99. GRB 250903A: SVOM detection of a burst
  100. EP250903a: Global MASTER-Net observations report

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