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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"

20362 results found.

  1. GRB 250625A: Enhanced Swift-XRT position
  2. GRB 250625A: Swift detection of a burst
  3. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  4. GRB 241018A: Maidanak optical observations
  5. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  6. IPN triangulation of GRB 250620C (long/bright)
  7. GRB 250620C: SVOM/GRM observation
  8. GRB 250620A: SVOM/GRM observation of a short burst
  9. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  10. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  11. GRB 250506A - SVOM/ECLAIRs Refined analysis
  12. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  13. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  14. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  15. GRB 250617B: Nickel telescope optical observations
  16. GRB 250615A: Kilonova-Catcher optical upper limits
  17. GRB 250617B: Assy AZT-20 Optical Observations
  18. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  19. GRB 250617B: Swift/UVOT Detection
  20. GRB 250617B: Kilonova-Catcher optical afterglow detection
  21. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  22. GRB 250617B: COLIBRÍ optical observations
  23. GRB 250617B: NOT NIR observations of the afterglow
  24. GRB 250617B: NUTTelA-TAO early time optical observations
  25. GRB 250617B: Enhanced Swift-XRT position
  26. GRB 250617B: SAO RAS optical observations
  27. GRB 250617B: Swift detection of a burst with an optical counterpart
  28. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  29. EP-WXT trigger 01709178975: GOTO optical upper limit
  30. Konus-Wind detection of GRB 250615A / EP250615a
  31. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  32. GRB 250615A: COLIBRÍ optical upper limit
  33. GRB 250615A: DDOTI Optical Upper Limit
  34. GRB 250615A: Swift/UVOT Upper Limits
  35. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  36. GRB 250615A: Swift-XRT refined Analysis
  37. sb25061207/SVOM: T120 OHP optical upper limit
  38. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  39. GRB 250615A: Enhanced Swift-XRT position
  40. GRB 250615A: Swift detection of a burst
  41. GRID detection of GRB 250612C
  42. sb25061207: Mephisto optical upper limits
  43. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  44. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  45. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  47. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  48. EP250612a: SVOM/VT optical candidate
  49. GRB 250612C: Fermi GBM Observation
  50. sb25061207: Swift-XRT observations
  51. EP250612a/GRB 250612B: JinShan optical upper limit
  52. sb25061207: SVOM/VT optical counterpart
  53. GRB 250610B: Swift-XRT refined Analysis
  54. EP250612a: Einstein Probe detection of an X-ray transient
  55. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  56. sb25061207: SVOM detection of a X-ray transient
  57. GRB 250610B - SVOM/ECLAIRs refined analysis
  58. Swift GRB250612.04: Global MASTER-Net observations report
  59. GRB 250610B: Swift/UVOT Detection
  60. EP250610A: Swift/UVOT Upper limits
  61. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  62. EP250610a: TNG NIR upper limit
  63. GRB 250610B: REM optical/NIR observations
  64. EP250610a: Liverpool Telescope optical upper limits
  65. GRB 250610B: additional Liverpool Telescope optical observations
  66. GRB 250610B: SVOM/VT optical counterpart
  67. GRB 250610B: OHP/T120 optical counterpart candidate
  68. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  69. GRB 250610B: SVOM detection of a long burst
  70. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  71. EP250610a: SVOM/VT optical upper limit
  72. EP250610a: REM optical/NIR observations
  73. GRB 250609A: Fermi GBM Observation
  74. GRBAlpha reentry on June 9, 2025
  75. EP250610a: COLIBRÍ optical upper limit
  76. EP250610a: Einstein Probe detection of an X-ray transient
  77. Fermi trigger No 771072240: Global MASTER-Net observations report
  78. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  79. GRB 250605A: Swift/UVOT Upper Limits
  80. GRB 250527C: CrAO Optical Upper Limit
  81. GRB 250607A: SVOM/GRM observation of a long burst
  82. The EP-WXT trigger 01709178244 is likely a flaring star
  83. The EP-WXT trigger 01709178069 is likely a flaring star
  84. GRB 250605A: Enhanced Swift-XRT position
  85. GRB 250605A: Swift detection of a burst
  86. IPN triangulation of GRB 250404B
  87. IPN triangulation of GRB 250529A
  88. GRB 250601A: PRIME H band upper limit.
  89. GRB 250601A: PRIME J band upper limit.
  90. GRB 250601A: VLT/FORS2 Optical Observation
  91. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  92. GRB 250603A: Swift/UVOT Upper Limits
  93. GRB 250603A: Swift-XRT refined Analysis
  94. GRB 250603A: Enhanced Swift-XRT position
  95. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  96. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  97. GRB 250602A: DDOTI Optical Upper Limit
  98. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  99. EP#01709177494: SVOM/VT optical observations
  100. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations

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