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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"

28232 results found.

  1. GRB 250903A: Swift-XRT afterglow detection
  2. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  3. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  4. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  5. EP250905a: Liverpool Telescope i-band upper limits
  6. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  7. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  8. EP250905a: Liverpool Telescope observations
  9. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  10. EP250905b: EP-WXT detection of a fast X-ray transient
  11. GRB 250905A: Swift-XRT refined Analysis
  12. EP250905a: JinShan likely optical counterpart detection
  13. GRB 250904A: Swift-BAT refined analysis
  14. GRB 250905A: Swift/UVOT Upper Limits
  15. GRB 250901A - SVOM/ECLAIRs refined analysis
  16. EP250905a: Einstein Probe detection of an X-ray transient
  17. GRB250904A: Liverpool Telescope upper limits
  18. GRB 250905A: Enhanced Swift-XRT position
  19. GRB 250904A: Swift/UVOT Detection
  20. GRB 250903A: Swift/UVOT detection
  21. GRB 250904A: Swift-XRT refined Analysis
  22. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  23. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  24. EP detected a brightening of LMXB 1ES 1735-26.9
  25. GRB 250905A: KAIT optical upper limit
  26. GRB 250905A: Swift detection of a burst
  27. GRB 250904A: Enhanced Swift-XRT position
  28. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 250904A: TRT optical counterpart detection
  30. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  31. GRB 250904A: Swift detection of a burst
  32. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  33. GRB 250902A: VZLUSAT-2 detection
  34. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  35. GRB 250903A: Swift-XRT observations
  36. EP250903a: Swift-XRT observations
  37. EP#01709201209: Swift-XRT observations
  38. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  39. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  40. GRB 250830C: VZLUSAT-2 detection
  41. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  42. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  44. GRB 250903A: EP-FXT counterpart detection
  45. GRB 250902A: GECAM-B detection
  46. GRB 250903A: LCO optical observation
  47. GRB 250903A: LCO optical afterglow detection
  48. GRB 250903A: SVOM/VT optical confirmation with VHF data
  49. EP250901a: Mondy, Assy and SAO RAS optical limits
  50. EP250903a: LCO candidate counterpart discovery
  51. GRB 250903A: TRT optical counterpart detection
  52. EP250903a: TRT optical observations
  53. EP250903a: Einstein Probe detection of an X-ray transient
  54. EP 250827B: Detection of supernova counterpart by LCO.
  55. GRB 250902B: SVOM/GRM observation
  56. EP250827b: SVOM/VT observation of AT 2025wkm
  57. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  58. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  59. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  60. GRB 250902A: Fermi GBM Detection
  61. GRB 250901A: Swift/UVOT Upper Limit
  62. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 250830B: Swift-XRT afterglow detection
  64. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  65. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  66. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  67. GRB 250902A: SVOM/GRM observation
  68. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  69. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  70. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  71. GRB 250901A: SVOM/VT optical afterglow with VHF data
  72. GRB 250901A: Swift-XRT afterglow detection
  73. EP250901a: Swift-XRT observations
  74. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  75. GRB 250901A: LCO optical upper limit
  76. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  77. EP250827b: Gemini Spectroscopy of AT 2025wkm
  78. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  79. EP250831a: NOT optical observations and tentative afterglow candidate
  80. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  81. GRB 250901A: SVOM detection of a burst
  82. EP250901a: Mephisto optical upper limits
  83. GRB 250830C: GECAM-B detection
  84. EP250901a: Einstein Probe detection of an X-ray transient
  85. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  86. EP250831a: Swift-XRT observations
  87. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  88. EP250831a: EP-WXT detection of a fast X-ray transient
  89. GRB 250831A: Swift-XRT counterpart detection
  90. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  91. GRB 250831A: SVOM/VT upper limit with VHF data
  92. GRB 250831A: SVOM detection of a soft burst
  93. GRB 250830B: Swift-XRT observations
  94. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  95. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  97. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  98. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  99. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  100. EP-WXT trigger 01709200994: Liverpool Telescope upper limits

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