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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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"

28066 results found.

  1. EP250911a: COLIBRÍ optical observations
  2. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  3. EP250911a: LCO optical counterpart discovery
  4. EP250911a: Einstein Probe detection of an X-ray transient
  5. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  6. GRB 250903A: SVOM/ECLAIRs refined analysis
  7. GRB 250911A: Enhanced Swift-XRT position
  8. GRB 250911A: Swift-XRT observations
  9. GRB 250911A: COLIBRÍ optical counterpart candidate
  10. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  11. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  12. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  13. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  14. GRB 250910A: SVOM/VT optical upper limit
  15. GRB 250910A: LCO optical upper limit
  16. EP250908b/EP#01709240653: Swift/UVOT Detection
  17. EP#01709240653: Swift-XRT observations
  18. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  19. EP250908c: SVOM/VT optical observation
  20. EP250908c: VLT/FORS2 optical counterpart identification
  21. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  22. EP250908b: SVOM/VT optical candidate
  23. Fermi GRB 250909A: Global MASTER-Net observations report
  24. EP250908c: Einstein Probe detection of an X-ray transient
  25. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  26. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  27. GRB 250907A: GECAM-B detection
  28. GRB 250905A: Swift-BAT refined analysis
  29. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  30. GRB 250903A: Swift-XRT afterglow detection
  31. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  32. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  33. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  34. EP250905a: Liverpool Telescope i-band upper limits
  35. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  36. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  37. EP250905a: Liverpool Telescope observations
  38. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  39. EP250905b: EP-WXT detection of a fast X-ray transient
  40. GRB 250905A: Swift-XRT refined Analysis
  41. EP250905a: JinShan likely optical counterpart detection
  42. GRB 250904A: Swift-BAT refined analysis
  43. GRB 250905A: Swift/UVOT Upper Limits
  44. GRB 250901A - SVOM/ECLAIRs refined analysis
  45. EP250905a: Einstein Probe detection of an X-ray transient
  46. GRB250904A: Liverpool Telescope upper limits
  47. GRB 250905A: Enhanced Swift-XRT position
  48. GRB 250904A: Swift/UVOT Detection
  49. GRB 250903A: Swift/UVOT detection
  50. GRB 250904A: Swift-XRT refined Analysis
  51. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  52. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  53. EP detected a brightening of LMXB 1ES 1735-26.9
  54. GRB 250905A: KAIT optical upper limit
  55. GRB 250905A: Swift detection of a burst
  56. GRB 250904A: Enhanced Swift-XRT position
  57. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 250904A: TRT optical counterpart detection
  59. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  60. GRB 250904A: Swift detection of a burst
  61. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  62. GRB 250902A: VZLUSAT-2 detection
  63. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  64. GRB 250903A: Swift-XRT observations
  65. EP250903a: Swift-XRT observations
  66. EP#01709201209: Swift-XRT observations
  67. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  68. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  69. GRB 250830C: VZLUSAT-2 detection
  70. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  71. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  73. GRB 250903A: EP-FXT counterpart detection
  74. GRB 250902A: GECAM-B detection
  75. GRB 250903A: LCO optical observation
  76. GRB 250903A: LCO optical afterglow detection
  77. GRB 250903A: SVOM/VT optical confirmation with VHF data
  78. EP250901a: Mondy, Assy and SAO RAS optical limits
  79. EP250903a: LCO candidate counterpart discovery
  80. GRB 250903A: TRT optical counterpart detection
  81. EP250903a: TRT optical observations
  82. EP250903a: Einstein Probe detection of an X-ray transient
  83. EP 250827B: Detection of supernova counterpart by LCO.
  84. GRB 250902B: SVOM/GRM observation
  85. EP250827b: SVOM/VT observation of AT 2025wkm
  86. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  87. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  88. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  89. GRB 250902A: Fermi GBM Detection
  90. GRB 250901A: Swift/UVOT Upper Limit
  91. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 250830B: Swift-XRT afterglow detection
  93. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  94. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  95. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  96. GRB 250902A: SVOM/GRM observation
  97. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  98. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  99. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 250901A: SVOM/VT optical afterglow with VHF data

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