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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').
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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"

42530 results found.

  1. EP250903a: Global MASTER-Net observations report
  2. EP250903a: TRT optical observations
  3. EP250903a: Einstein Probe detection of an X-ray transient
  4. EP 250827B: Detection of supernova counterpart by LCO.
  5. EP/WXT01709201159: GOTO optical follow-up
  6. EP250827b / AT 2025wkm: TRT optical observations
  7. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  8. EP250827b: continued Liverpool Telescope observations
  9. GRB 250902B: SVOM/GRM observation
  10. EP250827b: SVOM/VT observation of AT 2025wkm
  11. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  12. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  13. Fermi GRB 250902B: Global MASTER-Net observations report
  14. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  15. GRB 250902A: Fermi GBM Detection
  16. GRB 250901A: Swift/UVOT Upper Limit
  17. GRB 250902B: Fermi GBM Final Real-time Localization
  18. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 250830B: Swift-XRT afterglow detection
  20. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  21. EP250827b: Liverpool Telescope observations
  22. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  23. GRB 250902A: SVOM/GRM observation
  24. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  25. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  26. GRB 250901A: EP-FXT follow-up observation
  27. GRB 250901A: NOT optical observations
  28. GRB 250902A: Fermi GBM Final Real-time Localization
  29. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 250901A: SVOM/VT optical afterglow with VHF data
  31. GRB 250901A: Swift-XRT afterglow detection
  32. EP250901a: Swift-XRT observations
  33. GRB 250901A: LCO optical upper limit
  34. EP250827b: Swift observations of AT 2025wkm
  35. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  36. EP250827b: Gemini Spectroscopy of AT 2025wkm
  37. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  38. EP250831a: NOT optical observations and tentative afterglow candidate
  39. EP250827b: FTW Observations of AT 2025wkm
  40. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  41. GRB 250901A: SVOM detection of a burst
  42. GRB 250831B: SVOM/GRM observation
  43. GRB 250830C: Insight-HXMT detection
  44. EP250901a: Mephisto optical upper limits
  45. GRB 250830C: GECAM-B detection
  46. EP250901a: Global MASTER-Net observations report
  47. GRB 250830C: AstroSat CZTI detection of a long burst
  48. EP250901a: Einstein Probe detection of an X-ray transient
  49. EP250831a: EP-FXT follow-up observation
  50. EP250831a: Swift-XRT observations
  51. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  52. IceCube Alert 250831.75: Global MASTER-Net observations report
  53. EP250831a: Global MASTER-Net observations report
  54. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  55. EP250831a: EP-WXT detection of a fast X-ray transient
  56. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  57. GRB 250831A: Swift-XRT counterpart detection
  58. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. GRB 250831A: SVOM/VT upper limit with VHF data
  60. GRB 250831A: SVOM detection of a soft burst
  61. GRB 250830B: Swift-XRT observations
  62. EP250830a: Global MASTER-Net observations report
  63. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  64. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  65. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  66. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  67. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  68. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  69. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  70. GRB 250830B: Swift ToO observations
  71. GRB 250830B: MAXI/GSC detection
  72. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  73. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  74. The EP-WXT trigger 01709200994 is likely a flaring star
  75. GRB 250828B: Swift-BAT refined analysis
  76. EP250821a: SOAR observations
  77. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  78. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  79. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  80. GRB 250808B: SVOM detection of a burst through offline search
  81. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  82. EP250828a: Optical counterpart detection with Kinder observations
  83. EP250828a: Liverpool Telescope upper limits
  84. Swift GRB 250828B: Global MASTER-Net observations report
  85. EP250828a: Global MASTER-Net observations report
  86. EP-WXT trigger 01709200800 : KAIT optical observations
  87. EP250828a: KAIT optical upper limit
  88. EP250827a: Swift/UVOT Detection
  89. EP250828a: NOT optical counterpart confirmation
  90. EP250828a: SVOM/VT optical candidate
  91. EP250828a: Seimei/TriCCS optical counterpart detection
  92. GRB 250828B: Swift detection of a burst
  93. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  94. EP250828a: Optical upper limit with Kinder observations
  95. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  96. EP250827a: LCO observations show fading optical counterpart
  97. GRB 250828A: Fermi GBM Final Localization
  98. EP250828a: Einstein Probe detection of an X-ray transient
  99. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  100. GRID detection of GRB 250824A

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