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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"

28117 results found.

  1. EP250905a: Einstein Probe detection of an X-ray transient
  2. GRB250904A: Liverpool Telescope upper limits
  3. GRB 250905A: Enhanced Swift-XRT position
  4. GRB 250904A: Swift/UVOT Detection
  5. GRB 250903A: Swift/UVOT detection
  6. GRB 250904A: Swift-XRT refined Analysis
  7. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  8. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  9. EP detected a brightening of LMXB 1ES 1735-26.9
  10. GRB 250905A: KAIT optical upper limit
  11. GRB 250905A: Swift detection of a burst
  12. GRB 250904A: Enhanced Swift-XRT position
  13. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 250904A: TRT optical counterpart detection
  15. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  16. GRB 250904A: Swift detection of a burst
  17. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  18. GRB 250902A: VZLUSAT-2 detection
  19. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  20. GRB 250903A: Swift-XRT observations
  21. EP250903a: Swift-XRT observations
  22. EP#01709201209: Swift-XRT observations
  23. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  24. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  25. GRB 250830C: VZLUSAT-2 detection
  26. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  27. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  29. GRB 250903A: EP-FXT counterpart detection
  30. GRB 250902A: GECAM-B detection
  31. GRB 250903A: LCO optical observation
  32. GRB 250903A: LCO optical afterglow detection
  33. GRB 250903A: SVOM/VT optical confirmation with VHF data
  34. EP250901a: Mondy, Assy and SAO RAS optical limits
  35. EP250903a: LCO candidate counterpart discovery
  36. GRB 250903A: TRT optical counterpart detection
  37. EP250903a: TRT optical observations
  38. EP250903a: Einstein Probe detection of an X-ray transient
  39. EP 250827B: Detection of supernova counterpart by LCO.
  40. GRB 250902B: SVOM/GRM observation
  41. EP250827b: SVOM/VT observation of AT 2025wkm
  42. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  43. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  44. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  45. GRB 250902A: Fermi GBM Detection
  46. GRB 250901A: Swift/UVOT Upper Limit
  47. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 250830B: Swift-XRT afterglow detection
  49. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  50. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  51. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  52. GRB 250902A: SVOM/GRM observation
  53. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  54. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  55. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 250901A: SVOM/VT optical afterglow with VHF data
  57. GRB 250901A: Swift-XRT afterglow detection
  58. EP250901a: Swift-XRT observations
  59. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  60. GRB 250901A: LCO optical upper limit
  61. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  62. EP250827b: Gemini Spectroscopy of AT 2025wkm
  63. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  64. EP250831a: NOT optical observations and tentative afterglow candidate
  65. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  66. GRB 250901A: SVOM detection of a burst
  67. EP250901a: Mephisto optical upper limits
  68. GRB 250830C: GECAM-B detection
  69. EP250901a: Einstein Probe detection of an X-ray transient
  70. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  71. EP250831a: Swift-XRT observations
  72. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  73. EP250831a: EP-WXT detection of a fast X-ray transient
  74. GRB 250831A: Swift-XRT counterpart detection
  75. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. GRB 250831A: SVOM/VT upper limit with VHF data
  77. GRB 250831A: SVOM detection of a soft burst
  78. GRB 250830B: Swift-XRT observations
  79. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  80. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  81. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  82. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  83. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  84. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  85. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  86. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  87. GRB 250830B: MAXI/GSC detection
  88. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  89. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  90. GRB 250828B: Swift-BAT refined analysis
  91. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  92. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  93. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  94. EP250828a: Optical counterpart detection with Kinder observations
  95. EP250828a: Liverpool Telescope upper limits
  96. EP250828a: Global MASTER-Net observations report
  97. EP-WXT trigger 01709200800 : KAIT optical observations
  98. EP250828a: KAIT optical upper limit
  99. EP250827a: Swift/UVOT Detection
  100. EP250828a: NOT optical counterpart confirmation

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