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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').
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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"

5819 results found.

  1. GRB 250909B: Insight-HXMT detection
  2. GRB 250909B: SVOM/GRM observation
  3. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  4. EP250911a: COLIBRÍ optical observations
  5. Fermi GRB 250910B: Global MASTER-Net observations report
  6. EP250911a: LCO optical counterpart discovery
  7. EP250910a: Global MASTER-Net observations report
  8. EP250911a: Einstein Probe detection of an X-ray transient
  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. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  13. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  14. GRB 250909B: AstroSat CZTI detection of a long burst
  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 250910A: SVOM detection of a faint burst
  21. GRB 250702B: Late time Chandra observations
  22. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  23. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  24. EP250908c: SVOM/VT optical observation
  25. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  26. EP250908b: SVOM/VT optical candidate
  27. The EP-WXT trigger EP250908a/01709240652 is not a real source
  28. EP250908c: Global MASTER-Net observations report
  29. Fermi GRB 250909A: Global MASTER-Net observations report
  30. EP250908c: Einstein Probe detection of an X-ray transient
  31. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  32. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  33. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  34. GRB 250907A: GECAM-B detection
  35. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  36. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  37. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  38. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  39. EP250905a: Liverpool Telescope i-band upper limits
  40. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  41. EP250905b: EP-FXT follow-up observation
  42. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  43. EP250905a: Liverpool Telescope observations
  44. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP250905b: Global MASTER-Net observations report
  46. EP250905b: EP-WXT detection of a fast X-ray transient
  47. EP250905a: FTW one optical and multiple NIR counterpart candidates
  48. EP250905a: JinShan likely optical counterpart detection
  49. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  50. IceCube Alert 250905.84: Global MASTER-Net observations report
  51. EP250905a: Global MASTER-Net observations report
  52. GRB 250901A - SVOM/ECLAIRs refined analysis
  53. EP250905a: Einstein Probe detection of an X-ray transient
  54. GRB250904A: Liverpool Telescope upper limits
  55. EP detected a brightening of LMXB 1ES 1735-26.9
  56. GRB 250905A: Swift detection of a burst
  57. Swift GRB250905.09: Global MASTER-Net observations report
  58. Swift GRB 250904A: Global MASTER-Net observations report
  59. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 250904A: TRT optical counterpart detection
  61. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  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: refined analysis of the EP-WXT and EP-FXT observations
  66. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  67. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  68. The EP-WXT trigger 01709201209 is likely a flaring star
  69. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  70. GRB 250903A: EP-FXT counterpart detection
  71. GRB 250902A: GECAM-B detection
  72. GRB 250903A: LCO optical observation
  73. GRB 250903A: LCO optical afterglow detection
  74. GRB 250903A: SVOM/VT optical confirmation with VHF data
  75. EP250903a: SVOM/VT optical confirmation
  76. Subject GRB 250903A: SVOM/MXT afterglow detection
  77. EP250903a: LCO candidate counterpart discovery
  78. GRB 250903A: TRT optical counterpart detection
  79. GRB 250902B: AstroSat CZTI detection
  80. GRB 250903A: SVOM detection of a burst
  81. EP250903a: Global MASTER-Net observations report
  82. EP250903a: TRT optical observations
  83. EP250903a: Einstein Probe detection of an X-ray transient
  84. EP 250827B: Detection of supernova counterpart by LCO.
  85. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  86. EP250827b: continued Liverpool Telescope observations
  87. GRB 250902B: SVOM/GRM observation
  88. EP250827b: SVOM/VT observation of AT 2025wkm
  89. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  90. Fermi GRB 250902B: Global MASTER-Net observations report
  91. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  92. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  93. EP250827b: Liverpool Telescope observations
  94. GRB 250902A: SVOM/GRM observation
  95. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  96. GRB 250901A: EP-FXT follow-up observation
  97. GRB 250901A: SVOM/VT optical afterglow with VHF data
  98. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  99. GRB 250901A: LCO optical upper limit
  100. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates

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