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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"

28240 results found.

  1. EP250908c: Einstein Probe detection of an X-ray transient
  2. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  3. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  4. GRB 250907A: GECAM-B detection
  5. GRB 250905A: Swift-BAT refined analysis
  6. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  7. GRB 250903A: Swift-XRT afterglow detection
  8. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  9. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  10. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  11. EP250905a: Liverpool Telescope i-band upper limits
  12. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  13. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  14. EP250905a: Liverpool Telescope observations
  15. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  16. EP250905b: EP-WXT detection of a fast X-ray transient
  17. GRB 250905A: Swift-XRT refined Analysis
  18. EP250905a: JinShan likely optical counterpart detection
  19. GRB 250904A: Swift-BAT refined analysis
  20. GRB 250905A: Swift/UVOT Upper Limits
  21. GRB 250901A - SVOM/ECLAIRs refined analysis
  22. EP250905a: Einstein Probe detection of an X-ray transient
  23. GRB250904A: Liverpool Telescope upper limits
  24. GRB 250905A: Enhanced Swift-XRT position
  25. GRB 250904A: Swift/UVOT Detection
  26. GRB 250903A: Swift/UVOT detection
  27. GRB 250904A: Swift-XRT refined Analysis
  28. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  29. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  30. EP detected a brightening of LMXB 1ES 1735-26.9
  31. GRB 250905A: KAIT optical upper limit
  32. GRB 250905A: Swift detection of a burst
  33. GRB 250904A: Enhanced Swift-XRT position
  34. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 250904A: TRT optical counterpart detection
  36. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  37. GRB 250904A: Swift detection of a burst
  38. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  39. GRB 250902A: VZLUSAT-2 detection
  40. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  41. GRB 250903A: Swift-XRT observations
  42. EP250903a: Swift-XRT observations
  43. EP#01709201209: Swift-XRT observations
  44. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  45. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  46. GRB 250830C: VZLUSAT-2 detection
  47. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  48. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  50. GRB 250903A: EP-FXT counterpart detection
  51. GRB 250902A: GECAM-B detection
  52. GRB 250903A: LCO optical observation
  53. GRB 250903A: LCO optical afterglow detection
  54. GRB 250903A: SVOM/VT optical confirmation with VHF data
  55. EP250901a: Mondy, Assy and SAO RAS optical limits
  56. EP250903a: LCO candidate counterpart discovery
  57. GRB 250903A: TRT optical counterpart detection
  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. GRB 250902B: SVOM/GRM observation
  62. EP250827b: SVOM/VT observation of AT 2025wkm
  63. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  64. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  65. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  66. GRB 250902A: Fermi GBM Detection
  67. GRB 250901A: Swift/UVOT Upper Limit
  68. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 250830B: Swift-XRT afterglow detection
  70. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  71. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  72. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  73. GRB 250902A: SVOM/GRM observation
  74. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  75. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  76. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 250901A: SVOM/VT optical afterglow with VHF data
  78. GRB 250901A: Swift-XRT afterglow detection
  79. EP250901a: Swift-XRT observations
  80. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  81. GRB 250901A: LCO optical upper limit
  82. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  83. EP250827b: Gemini Spectroscopy of AT 2025wkm
  84. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  85. EP250831a: NOT optical observations and tentative afterglow candidate
  86. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  87. GRB 250901A: SVOM detection of a burst
  88. EP250901a: Mephisto optical upper limits
  89. GRB 250830C: GECAM-B detection
  90. EP250901a: Einstein Probe detection of an X-ray transient
  91. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  92. EP250831a: Swift-XRT observations
  93. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  94. EP250831a: EP-WXT detection of a fast X-ray transient
  95. GRB 250831A: Swift-XRT counterpart detection
  96. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  97. GRB 250831A: SVOM/VT upper limit with VHF data
  98. GRB 250831A: SVOM detection of a soft burst
  99. GRB 250830B: Swift-XRT observations
  100. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up

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