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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"

32507 results found.

  1. GRB 250807A: SVOM/VT optical observation
  2. EP250806a: Upper limit from Fermi-GBM Observations
  3. GRB 250805A: Kilonova-Catcher optical upper limits
  4. EP250806a:SVOM/VT refined analysis
  5. GRB 250805A: Swift/UVOT Upper Limits
  6. GRB 250806A: Swift/UVOT U-band detection
  7. EP250806a: Liverpool telescope optical upper limit
  8. GRB 250806A: EP-FXT observation
  9. EP#01709198415/EP250806a: Swift-XRT observations
  10. EP250806a: Global MASTER-Net observations report
  11. EP250802a: EP-FXT follow-up observation
  12. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  13. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  14. EP250806a: SVOM /VT optical candidate
  15. GRB 250806A: J-band upper limit from WINTER
  16. GRB 250805A: Swift-BAT refined analysis
  17. GRB 250806A: KAIT optical upper limit
  18. GRB 250806A: SVOM/VT refined analysis
  19. EP250806a: COLIBRÍ optical upper limit
  20. GRB 250806A: Kilonova-Catcher optical upper limits
  21. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 250806A: SVOM/VT optical upper limit
  23. GRB 250805A: SVOM/VT optical counterpart
  24. GRB 250805A: ESO/VLT observations
  25. GRB 250805A: TRT optical upper limits
  26. GRB 250804B: Tiled Swift observations
  27. EP250802a: additional Liverpool Telescope upper limits
  28. EP250730a: SVOM/VT optical upper limit
  29. EP250802a: Liverpool Telescope optical upper limits
  30. EP250802a: Global MASTER-Net observations report
  31. EP250802a: GROWTH-India Telescope optical upper limit
  32. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  33. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  35. GRB 250702B: SMA observations
  36. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  37. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  38. EP250711a: CrAO and Assy optical observations
  39. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  40. EP250730a: Global MASTER-Net observations report
  41. EP250730a: COLIBRÍ optical upper limit
  42. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  43. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  44. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  45. GRB 250725A: AstroSat CZTI detection
  46. GRB 250727A: EP-FXT follow-up observation
  47. GRB 250725A: PRIME near-infrared observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  49. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  50. GRB: Clarification on Gamma-Ray Burst Naming Convention
  51. GRB 250727A: SVOM/ECLAIRs refined analysis
  52. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  53. GRB 250728A: COLIBRÍ optical upper limit
  54. GRB 250728A: Fermi GBM Observation
  55. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  56. GRB 250728A: Swift ToO observations
  57. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  58. GRB 250727A: AST3-2 Upper limit
  59. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  60. GRB 250727A: EP-FXT counterpart detection
  61. GRB250727A: SVOM/VT optical upper limit
  62. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  65. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  66. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  67. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  68. GRB 250725A: Fermi GBM Observation
  69. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  70. GRB 250725A: Swift-BAT refined analysis
  71. Konus-Wind detection of GRB 250725A
  72. GRB 250725A: SVOM/GRM observation
  73. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  74. GRB 250725A: Swift/UVOT Upper Limits
  75. GRB 250725A: Fermi-LAT detection
  76. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  77. GRB 250725A: BOOTES-7 early optical detection
  78. GRB 250725A: SVOM/VT optical candidate
  79. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  80. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  82. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  83. SVOM J195836+32283 is not a real source
  84. SVOM J195836+32283/sb25072103: Second VT observation
  85. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  86. GRB 250721A: Fermi GBM Observation
  87. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  88. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  89. GRB 250713A : SVOM/ECLAIRs refined analysis
  90. GRB 250717B: SVOM/GRM observation
  91. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  92. GRB 250721A: Tiled Swift observations
  93. GRB 250721A: MAXI/GSC detection
  94. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  95. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  96. GRB 250717B: COLIBRÍ optical upper limit
  97. GRB 250718B: Fermi GBM Final Localization Correction
  98. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  99. GRB 250717B: Swift ToO observations
  100. GRB 270713A: Kitab and AbAO Optical Observations

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