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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"

32494 results found.

  1. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  2. EP250806a: SVOM /VT optical candidate
  3. GRB 250806A: J-band upper limit from WINTER
  4. GRB 250805A: Swift-BAT refined analysis
  5. GRB 250806A: KAIT optical upper limit
  6. GRB 250806A: SVOM/VT refined analysis
  7. EP250806a: COLIBRÍ optical upper limit
  8. GRB 250806A: Kilonova-Catcher optical upper limits
  9. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRB 250806A: SVOM/VT optical upper limit
  11. GRB 250805A: SVOM/VT optical counterpart
  12. GRB 250805A: ESO/VLT observations
  13. GRB 250805A: TRT optical upper limits
  14. GRB 250804B: Tiled Swift observations
  15. EP250802a: additional Liverpool Telescope upper limits
  16. EP250730a: SVOM/VT optical upper limit
  17. EP250802a: Liverpool Telescope optical upper limits
  18. EP250802a: Global MASTER-Net observations report
  19. EP250802a: GROWTH-India Telescope optical upper limit
  20. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  21. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  23. GRB 250702B: SMA observations
  24. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  25. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  26. EP250711a: CrAO and Assy optical observations
  27. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  28. EP250730a: Global MASTER-Net observations report
  29. EP250730a: COLIBRÍ optical upper limit
  30. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  31. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  32. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  33. GRB 250725A: AstroSat CZTI detection
  34. GRB 250727A: EP-FXT follow-up observation
  35. GRB 250725A: PRIME near-infrared observations
  36. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  37. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  38. GRB: Clarification on Gamma-Ray Burst Naming Convention
  39. GRB 250727A: SVOM/ECLAIRs refined analysis
  40. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  41. GRB 250728A: COLIBRÍ optical upper limit
  42. GRB 250728A: Fermi GBM Observation
  43. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  44. GRB 250728A: Swift ToO observations
  45. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  46. GRB 250727A: AST3-2 Upper limit
  47. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  48. GRB 250727A: EP-FXT counterpart detection
  49. GRB250727A: SVOM/VT optical upper limit
  50. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  53. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  54. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  55. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  56. GRB 250725A: Fermi GBM Observation
  57. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  58. GRB 250725A: Swift-BAT refined analysis
  59. Konus-Wind detection of GRB 250725A
  60. GRB 250725A: SVOM/GRM observation
  61. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  62. GRB 250725A: Swift/UVOT Upper Limits
  63. GRB 250725A: Fermi-LAT detection
  64. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  65. GRB 250725A: BOOTES-7 early optical detection
  66. GRB 250725A: SVOM/VT optical candidate
  67. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  68. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  70. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  71. SVOM J195836+32283 is not a real source
  72. SVOM J195836+32283/sb25072103: Second VT observation
  73. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  74. GRB 250721A: Fermi GBM Observation
  75. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  76. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  77. GRB 250713A : SVOM/ECLAIRs refined analysis
  78. GRB 250717B: SVOM/GRM observation
  79. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  80. GRB 250721A: Tiled Swift observations
  81. GRB 250721A: MAXI/GSC detection
  82. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  83. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  84. GRB 250717B: COLIBRÍ optical upper limit
  85. GRB 250718B: Fermi GBM Final Localization Correction
  86. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  87. GRB 250717B: Swift ToO observations
  88. GRB 270713A: Kitab and AbAO Optical Observations
  89. GRB 250717B: Fermi GBM Observation
  90. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  91. Konus-Wind detection of GRB 250716A
  92. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  93. GRB 250716A: Swift ToO observations
  94. GRB 250714A: SVOM/GRM observation
  95. Fermi GRB 250716A: Global MASTER-Net observations report
  96. Fermi GRB 250715A: Global MASTER-Net observations report
  97. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  98. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  99. GRB 250713A: Mephisto optical upper limits
  100. Fermi GRB 250714A: Global MASTER-Net observations report

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