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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"

28114 results found.

  1. GRB 250905A: Enhanced Swift-XRT position
  2. GRB 250904A: Swift/UVOT Detection
  3. GRB 250903A: Swift/UVOT detection
  4. GRB 250904A: Swift-XRT refined Analysis
  5. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  6. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  7. EP detected a brightening of LMXB 1ES 1735-26.9
  8. GRB 250905A: KAIT optical upper limit
  9. GRB 250905A: Swift detection of a burst
  10. GRB 250904A: Enhanced Swift-XRT position
  11. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 250904A: TRT optical counterpart detection
  13. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  14. GRB 250904A: Swift detection of a burst
  15. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  16. GRB 250902A: VZLUSAT-2 detection
  17. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  18. GRB 250903A: Swift-XRT observations
  19. EP250903a: Swift-XRT observations
  20. EP#01709201209: Swift-XRT observations
  21. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  22. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  23. GRB 250830C: VZLUSAT-2 detection
  24. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  25. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  27. GRB 250903A: EP-FXT counterpart detection
  28. GRB 250902A: GECAM-B detection
  29. GRB 250903A: LCO optical observation
  30. GRB 250903A: LCO optical afterglow detection
  31. GRB 250903A: SVOM/VT optical confirmation with VHF data
  32. EP250901a: Mondy, Assy and SAO RAS optical limits
  33. EP250903a: LCO candidate counterpart discovery
  34. GRB 250903A: TRT optical counterpart detection
  35. EP250903a: TRT optical observations
  36. EP250903a: Einstein Probe detection of an X-ray transient
  37. EP 250827B: Detection of supernova counterpart by LCO.
  38. GRB 250902B: SVOM/GRM observation
  39. EP250827b: SVOM/VT observation of AT 2025wkm
  40. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  41. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  42. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  43. GRB 250902A: Fermi GBM Detection
  44. GRB 250901A: Swift/UVOT Upper Limit
  45. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 250830B: Swift-XRT afterglow detection
  47. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  48. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  49. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  50. GRB 250902A: SVOM/GRM observation
  51. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  52. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  53. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 250901A: SVOM/VT optical afterglow with VHF data
  55. GRB 250901A: Swift-XRT afterglow detection
  56. EP250901a: Swift-XRT observations
  57. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  58. GRB 250901A: LCO optical upper limit
  59. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  60. EP250827b: Gemini Spectroscopy of AT 2025wkm
  61. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  62. EP250831a: NOT optical observations and tentative afterglow candidate
  63. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  64. GRB 250901A: SVOM detection of a burst
  65. EP250901a: Mephisto optical upper limits
  66. GRB 250830C: GECAM-B detection
  67. EP250901a: Einstein Probe detection of an X-ray transient
  68. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  69. EP250831a: Swift-XRT observations
  70. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  71. EP250831a: EP-WXT detection of a fast X-ray transient
  72. GRB 250831A: Swift-XRT counterpart detection
  73. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  74. GRB 250831A: SVOM/VT upper limit with VHF data
  75. GRB 250831A: SVOM detection of a soft burst
  76. GRB 250830B: Swift-XRT observations
  77. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  78. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  79. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  80. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  81. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  82. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  83. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  84. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  85. GRB 250830B: MAXI/GSC detection
  86. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  87. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  88. GRB 250828B: Swift-BAT refined analysis
  89. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  90. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  91. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  92. EP250828a: Optical counterpart detection with Kinder observations
  93. EP250828a: Liverpool Telescope upper limits
  94. EP250828a: Global MASTER-Net observations report
  95. EP-WXT trigger 01709200800 : KAIT optical observations
  96. EP250828a: KAIT optical upper limit
  97. EP250827a: Swift/UVOT Detection
  98. EP250828a: NOT optical counterpart confirmation
  99. EP250828a: SVOM/VT optical candidate
  100. EP250828a: Seimei/TriCCS optical counterpart detection

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