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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"

26562 results found.

  1. EP detected a brightening of LMXB 1ES 1735-26.9
  2. GRB 250905A: KAIT optical upper limit
  3. GRB 250905A: Swift detection of a burst
  4. GRB 250904A: Enhanced Swift-XRT position
  5. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 250904A: TRT optical counterpart detection
  7. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  8. GRB 250904A: Swift detection of a burst
  9. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 250902A: VZLUSAT-2 detection
  11. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  12. GRB 250903A: Swift-XRT observations
  13. EP250903a: Swift-XRT observations
  14. EP#01709201209: Swift-XRT observations
  15. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  16. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  17. GRB 250830C: VZLUSAT-2 detection
  18. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  19. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  20. The EP-WXT trigger 01709201209 is likely a flaring star
  21. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  22. GRB 250902A: GECAM-B detection
  23. GRB 250903A: LCO optical observation
  24. GRB 250903A: LCO optical afterglow detection
  25. GRB 250903A: SVOM/VT optical confirmation with VHF data
  26. EP250901a: Mondy, Assy and SAO RAS optical limits
  27. GRB 250903A: TRT optical counterpart detection
  28. GRB 250902B: AstroSat CZTI detection
  29. GRB 250903A: SVOM detection of a burst
  30. EP250903a: TRT optical observations
  31. EP250903a: Einstein Probe detection of an X-ray transient
  32. EP 250827B: Detection of supernova counterpart by LCO.
  33. GRB 250902B: SVOM/GRM observation
  34. EP250827b: SVOM/VT observation of AT 2025wkm
  35. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  36. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  37. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  38. GRB 250902A: Fermi GBM Detection
  39. GRB 250901A: Swift/UVOT Upper Limit
  40. GRB 250902B: Fermi GBM Final Real-time Localization
  41. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  42. GRB 250830B: Swift-XRT afterglow detection
  43. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  44. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  45. GRB 250902A: SVOM/GRM observation
  46. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  47. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  48. GRB 250901A: EP-FXT follow-up observation
  49. GRB 250902A: Fermi GBM Final Real-time Localization
  50. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 250901A: SVOM/VT optical afterglow with VHF data
  52. GRB 250901A: Swift-XRT afterglow detection
  53. EP250901a: Swift-XRT observations
  54. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  55. GRB 250901A: LCO optical upper limit
  56. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  57. EP250831a: NOT optical observations and tentative afterglow candidate
  58. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  59. GRB 250901A: SVOM detection of a burst
  60. EP250901a: Mephisto optical upper limits
  61. GRB 250830C: GECAM-B detection
  62. EP250901a: Einstein Probe detection of an X-ray transient
  63. EP250831a: EP-FXT follow-up observation
  64. EP250831a: Swift-XRT observations
  65. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  66. EP250831a: EP-WXT detection of a fast X-ray transient
  67. GRB 250831A: Swift-XRT counterpart detection
  68. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. GRB 250831A: SVOM/VT upper limit with VHF data
  70. GRB 250831A: SVOM detection of a soft burst
  71. GRB 250830B: Swift-XRT observations
  72. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  73. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  74. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  75. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  76. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  77. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  78. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  79. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  80. The EP-WXT trigger 01709200994 is likely a flaring star
  81. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  82. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  83. GRB 250808B: SVOM detection of a burst through offline search
  84. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP250828a: Optical counterpart detection with Kinder observations
  86. EP250828a: Liverpool Telescope upper limits
  87. EP-WXT trigger 01709200800 : KAIT optical observations
  88. EP250828a: KAIT optical upper limit
  89. EP250827a: Swift/UVOT Detection
  90. EP250828a: NOT optical counterpart confirmation
  91. EP250828a: SVOM/VT optical candidate
  92. EP250828a: Seimei/TriCCS optical counterpart detection
  93. EP250828a: Optical upper limit with Kinder observations
  94. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  95. EP250828a: Einstein Probe detection of an X-ray transient
  96. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  97. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  98. EP250827a: confirmation of optical rebrightening with LCO
  99. GRB 250826A: SVOM/GRM observation
  100. EP250827A: An optical rebrightening was detected by LCO.

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