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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"

32565 results found.

  1. Fermi GRB 250909A: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  3. GRB 250905A: Swift-BAT refined analysis
  4. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  5. GRB 250903A: Swift-XRT afterglow detection
  6. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  7. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  8. EP250905a: Liverpool Telescope i-band upper limits
  9. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  10. EP250905b: EP-FXT follow-up observation
  11. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  12. EP250905a: Liverpool Telescope observations
  13. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  14. EP250905b: Global MASTER-Net observations report
  15. EP250905a: FTW one optical and multiple NIR counterpart candidates
  16. EP250905a: JinShan likely optical counterpart detection
  17. GRB 250904A: Swift-BAT refined analysis
  18. GRB 250905A: Swift/UVOT Upper Limits
  19. EP250905a: Global MASTER-Net observations report
  20. GRB 250901A - SVOM/ECLAIRs refined analysis
  21. GRB250904A: Liverpool Telescope upper limits
  22. GRB 250904A: Swift/UVOT Detection
  23. GRB 250903A: Swift/UVOT detection
  24. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  25. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  26. GRB 250905A: KAIT optical upper limit
  27. Swift GRB 250904A: Global MASTER-Net observations report
  28. GRB 250904A: TRT optical counterpart detection
  29. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  30. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  31. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  32. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  33. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  34. GRB 250902A: VZLUSAT-2 detection
  35. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  36. GRB 250903A: Swift-XRT observations
  37. EP250903a: Swift-XRT observations
  38. EP#01709201209: Swift-XRT observations
  39. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  40. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  41. GRB 250830C: VZLUSAT-2 detection
  42. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  43. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  44. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  45. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  46. GRB 250903A: EP-FXT counterpart detection
  47. GRB 250902A: GECAM-B detection
  48. GRB 250903A: LCO optical observation
  49. GRB 250903A: LCO optical afterglow detection
  50. GRB 250903A: SVOM/VT optical confirmation with VHF data
  51. EP250903a: SVOM/VT optical confirmation
  52. EP250901a: Mondy, Assy and SAO RAS optical limits
  53. Subject GRB 250903A: SVOM/MXT afterglow detection
  54. EP250903a: LCO candidate counterpart discovery
  55. GRB 250903A: TRT optical counterpart detection
  56. GRB 250902B: AstroSat CZTI detection
  57. EP250903a: Global MASTER-Net observations report
  58. EP250903a: TRT optical observations
  59. EP250903a: Einstein Probe detection of an X-ray transient
  60. EP 250827B: Detection of supernova counterpart by LCO.
  61. EP250827b / AT 2025wkm: TRT optical observations
  62. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  63. EP250827b: continued Liverpool Telescope observations
  64. GRB 250902B: SVOM/GRM observation
  65. EP250827b: SVOM/VT observation of AT 2025wkm
  66. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  67. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  68. Fermi GRB 250902B: Global MASTER-Net observations report
  69. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  70. GRB 250902A: Fermi GBM Detection
  71. GRB 250901A: Swift/UVOT Upper Limit
  72. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  73. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  74. EP250827b: Liverpool Telescope observations
  75. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  76. GRB 250902A: SVOM/GRM observation
  77. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  78. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 250901A: EP-FXT follow-up observation
  80. GRB 250901A: NOT optical observations
  81. GRB 250901A: SVOM/VT optical afterglow with VHF data
  82. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  83. GRB 250901A: LCO optical upper limit
  84. EP250827b: Swift observations of AT 2025wkm
  85. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  86. EP250827b: Gemini Spectroscopy of AT 2025wkm
  87. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  88. EP250831a: NOT optical observations and tentative afterglow candidate
  89. EP250827b: FTW Observations of AT 2025wkm
  90. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  91. GRB 250830C: Insight-HXMT detection
  92. EP250901a: Mephisto optical upper limits
  93. EP250901a: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  95. EP250831a: EP-FXT follow-up observation
  96. EP250831a: Swift-XRT observations
  97. EP250831a: Global MASTER-Net observations report
  98. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  99. GRB 250831A: Swift-XRT counterpart detection
  100. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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