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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"

26661 results found.

  1. GRB 250905A: KAIT optical upper limit
  2. GRB 250905A: Swift detection of a burst
  3. GRB 250904A: Enhanced Swift-XRT position
  4. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 250904A: TRT optical counterpart detection
  6. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  7. GRB 250904A: Swift detection of a burst
  8. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 250902A: VZLUSAT-2 detection
  10. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  11. GRB 250903A: Swift-XRT observations
  12. EP250903a: Swift-XRT observations
  13. EP#01709201209: Swift-XRT observations
  14. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  15. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  16. GRB 250830C: VZLUSAT-2 detection
  17. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  18. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  19. The EP-WXT trigger 01709201209 is likely a flaring star
  20. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  21. GRB 250902A: GECAM-B detection
  22. GRB 250903A: LCO optical observation
  23. GRB 250903A: LCO optical afterglow detection
  24. GRB 250903A: SVOM/VT optical confirmation with VHF data
  25. EP250901a: Mondy, Assy and SAO RAS optical limits
  26. GRB 250903A: TRT optical counterpart detection
  27. GRB 250902B: AstroSat CZTI detection
  28. GRB 250903A: SVOM detection of a burst
  29. EP250903a: TRT optical observations
  30. EP250903a: Einstein Probe detection of an X-ray transient
  31. EP 250827B: Detection of supernova counterpart by LCO.
  32. GRB 250902B: SVOM/GRM observation
  33. EP250827b: SVOM/VT observation of AT 2025wkm
  34. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  35. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  36. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  37. GRB 250902A: Fermi GBM Detection
  38. GRB 250901A: Swift/UVOT Upper Limit
  39. GRB 250902B: Fermi GBM Final Real-time Localization
  40. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 250830B: Swift-XRT afterglow detection
  42. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  43. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  44. GRB 250902A: SVOM/GRM observation
  45. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  46. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  47. GRB 250901A: EP-FXT follow-up observation
  48. GRB 250902A: Fermi GBM Final Real-time Localization
  49. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  50. GRB 250901A: SVOM/VT optical afterglow with VHF data
  51. GRB 250901A: Swift-XRT afterglow detection
  52. EP250901a: Swift-XRT observations
  53. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  54. GRB 250901A: LCO optical upper limit
  55. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  56. EP250831a: NOT optical observations and tentative afterglow candidate
  57. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  58. GRB 250901A: SVOM detection of a burst
  59. EP250901a: Mephisto optical upper limits
  60. GRB 250830C: GECAM-B detection
  61. EP250901a: Einstein Probe detection of an X-ray transient
  62. EP250831a: EP-FXT follow-up observation
  63. EP250831a: Swift-XRT observations
  64. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  65. EP250831a: EP-WXT detection of a fast X-ray transient
  66. GRB 250831A: Swift-XRT counterpart detection
  67. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  68. GRB 250831A: SVOM/VT upper limit with VHF data
  69. GRB 250831A: SVOM detection of a soft burst
  70. GRB 250830B: Swift-XRT observations
  71. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  72. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  74. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  75. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  76. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  77. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  78. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  79. The EP-WXT trigger 01709200994 is likely a flaring star
  80. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  81. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  82. GRB 250808B: SVOM detection of a burst through offline search
  83. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  84. EP250828a: Optical counterpart detection with Kinder observations
  85. EP250828a: Liverpool Telescope upper limits
  86. EP-WXT trigger 01709200800 : KAIT optical observations
  87. EP250828a: KAIT optical upper limit
  88. EP250827a: Swift/UVOT Detection
  89. EP250828a: NOT optical counterpart confirmation
  90. EP250828a: SVOM/VT optical candidate
  91. EP250828a: Seimei/TriCCS optical counterpart detection
  92. EP250828a: Optical upper limit with Kinder observations
  93. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  94. EP250828a: Einstein Probe detection of an X-ray transient
  95. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  96. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  97. EP250827a: confirmation of optical rebrightening with LCO
  98. GRB 250826A: SVOM/GRM observation
  99. EP250827A: An optical rebrightening was detected by LCO.
  100. EP250827a: Swift-XRT counterpart detection

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