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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"

28233 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  2. GRB 250903A: Swift-XRT afterglow detection
  3. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  4. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  5. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  6. EP250905a: Liverpool Telescope i-band upper limits
  7. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  8. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  9. EP250905a: Liverpool Telescope observations
  10. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  11. EP250905b: EP-WXT detection of a fast X-ray transient
  12. GRB 250905A: Swift-XRT refined Analysis
  13. EP250905a: JinShan likely optical counterpart detection
  14. GRB 250904A: Swift-BAT refined analysis
  15. GRB 250905A: Swift/UVOT Upper Limits
  16. GRB 250901A - SVOM/ECLAIRs refined analysis
  17. EP250905a: Einstein Probe detection of an X-ray transient
  18. GRB250904A: Liverpool Telescope upper limits
  19. GRB 250905A: Enhanced Swift-XRT position
  20. GRB 250904A: Swift/UVOT Detection
  21. GRB 250903A: Swift/UVOT detection
  22. GRB 250904A: Swift-XRT refined Analysis
  23. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  24. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  25. EP detected a brightening of LMXB 1ES 1735-26.9
  26. GRB 250905A: KAIT optical upper limit
  27. GRB 250905A: Swift detection of a burst
  28. GRB 250904A: Enhanced Swift-XRT position
  29. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 250904A: TRT optical counterpart detection
  31. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  32. GRB 250904A: Swift detection of a burst
  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. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  45. GRB 250903A: EP-FXT counterpart detection
  46. GRB 250902A: GECAM-B detection
  47. GRB 250903A: LCO optical observation
  48. GRB 250903A: LCO optical afterglow detection
  49. GRB 250903A: SVOM/VT optical confirmation with VHF data
  50. EP250901a: Mondy, Assy and SAO RAS optical limits
  51. EP250903a: LCO candidate counterpart discovery
  52. GRB 250903A: TRT optical counterpart detection
  53. EP250903a: TRT optical observations
  54. EP250903a: Einstein Probe detection of an X-ray transient
  55. EP 250827B: Detection of supernova counterpart by LCO.
  56. GRB 250902B: SVOM/GRM observation
  57. EP250827b: SVOM/VT observation of AT 2025wkm
  58. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  59. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  60. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  61. GRB 250902A: Fermi GBM Detection
  62. GRB 250901A: Swift/UVOT Upper Limit
  63. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 250830B: Swift-XRT afterglow detection
  65. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  66. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  67. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  68. GRB 250902A: SVOM/GRM observation
  69. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  70. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  71. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 250901A: SVOM/VT optical afterglow with VHF data
  73. GRB 250901A: Swift-XRT afterglow detection
  74. EP250901a: Swift-XRT observations
  75. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  76. GRB 250901A: LCO optical upper limit
  77. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  78. EP250827b: Gemini Spectroscopy of AT 2025wkm
  79. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  80. EP250831a: NOT optical observations and tentative afterglow candidate
  81. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  82. GRB 250901A: SVOM detection of a burst
  83. EP250901a: Mephisto optical upper limits
  84. GRB 250830C: GECAM-B detection
  85. EP250901a: Einstein Probe detection of an X-ray transient
  86. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  87. EP250831a: Swift-XRT observations
  88. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  89. EP250831a: EP-WXT detection of a fast X-ray transient
  90. GRB 250831A: Swift-XRT counterpart detection
  91. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. GRB 250831A: SVOM/VT upper limit with VHF data
  93. GRB 250831A: SVOM detection of a soft burst
  94. GRB 250830B: Swift-XRT observations
  95. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  96. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  97. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  98. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  99. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  100. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate

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