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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').
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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"

21855 results found.

  1. GRB 250920B: SVOM/C-GFT optical observations
  2. GRB 250920C: GOTO optical counterpart candidate
  3. GRB 250919A / EP250919a: LCO optical observation
  4. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  5. Swift GRB 250920B: Global MASTER-Net observations report
  6. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  7. GRB 250916A: Mondy R-band optical observations
  8. Fermi GRB 250918A: Global MASTER-Net observations report
  9. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  10. GRB 250919A: Swift-XRT afterglow detection
  11. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  12. EP250919a: Global MASTER-Net observations report
  13. EP250919a: Einstein Probe detection of an X-ray transient
  14. Fermi GRB 250919A: Global MASTER-Net observations report
  15. GRB 250916A: KAIT optical observations
  16. GRB 250917B: VLT/HAWK-I near-infrared observations
  17. GRB 250916A: further SAO RAS optical observations
  18. GRB 250912A: SVOM/ECLAIRs refined analysis
  19. GRB 250917B: Swift/UVOT Upper Limits
  20. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  21. GRB 250916A: Swift-XRT observations
  22. EP250916a: EP-FXT follow-up observation
  23. GRB 250916A: MAO/AZT-22 optical observations
  24. GRB 250916A: SAO RAS optical observations
  25. GRB 250916A : GIT optical observations
  26. GRB250917B: WFST optical observations
  27. GRB 250916A: Swift ToO observations
  28. GRB 250917B: Swift-XRT observations
  29. Fermi GRB 250917B: Global MASTER-Net observations report
  30. GRB 250916A: GOTO optical counterpart candidate
  31. GRB 250910A: SVOM/ECLAIRs refined analysis
  32. EP250916a: Einstein Probe detection of an X-ray transient
  33. Fermi GRB 250916A: Global MASTER-Net observations report
  34. EP250827b: VLA Observations
  35. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  36. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  37. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  38. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  39. GRB 250912A: Swift-XRT observations
  40. GRB250912A: VLT/HAWK-I follow-up observations
  41. GRB 250912A: VLT observations
  42. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  43. Fermi GRB 250912A: Global MASTER-Net observations report
  44. EP250911a: Global MASTER-Net observations report
  45. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  46. EP250911a: Upper limit from Fermi-GBM Observations
  47. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  48. GRB 250911A: MASTER optical counterpart observations
  49. EP250911a: SAO RAS optical observations
  50. EP250911a: Swift-XRT observations
  51. EP250911a: Optical detection with Kinder observations
  52. GRB 250911A: Swift/UVOT Detection
  53. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  54. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  55. EP250911a: COLIBRÍ optical observations
  56. Fermi GRB 250910B: Global MASTER-Net observations report
  57. EP250910a: Global MASTER-Net observations report
  58. GRB 250903A: SVOM/ECLAIRs refined analysis
  59. GRB 250911A: Swift-XRT observations
  60. GRB 250911A: COLIBRÍ optical counterpart candidate
  61. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  62. GRB 250702B: Late time Chandra observations
  63. EP250908b/EP#01709240653: Swift/UVOT Detection
  64. EP#01709240653: Swift-XRT observations
  65. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250908c: Global MASTER-Net observations report
  67. Fermi GRB 250909A: Global MASTER-Net observations report
  68. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  69. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  70. GRB 250903A: Swift-XRT afterglow detection
  71. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  72. EP250905b: EP-FXT follow-up observation
  73. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  74. EP250905a: Liverpool Telescope observations
  75. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  76. EP250905b: Global MASTER-Net observations report
  77. EP250905b: EP-WXT detection of a fast X-ray transient
  78. EP250905a: FTW one optical and multiple NIR counterpart candidates
  79. EP250905a: JinShan likely optical counterpart detection
  80. IceCube Alert 250905.84: Global MASTER-Net observations report
  81. GRB 250905A: Swift/UVOT Upper Limits
  82. EP250905a: Global MASTER-Net observations report
  83. GRB 250901A - SVOM/ECLAIRs refined analysis
  84. GRB 250904A: Swift/UVOT Detection
  85. GRB 250903A: Swift/UVOT detection
  86. Swift GRB250905.09: Global MASTER-Net observations report
  87. Swift GRB 250904A: Global MASTER-Net observations report
  88. GRB 250904A: TRT optical counterpart detection
  89. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  90. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  91. GRB 250903A: Swift-XRT observations
  92. EP250903a: Swift-XRT observations
  93. EP#01709201209: Swift-XRT observations
  94. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  95. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  96. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  97. GRB 250903A: LCO optical afterglow detection
  98. EP250903a: SVOM/VT optical confirmation
  99. EP250903a: LCO candidate counterpart discovery
  100. GRB 250903A: TRT optical counterpart detection

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