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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').
Advanced Search

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"

16007 results found.

  1. GRB250920C: LCOGT Optical Detection
  2. GRB 250920B: SVOM/C-GFT optical observations
  3. GRB 250920C: GOTO optical counterpart candidate
  4. GRB 250919A / EP250919a: LCO optical observation
  5. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  6. GRB 250919A/EP250919a: SVOM/VT optical observation
  7. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  8. GRB 250916A: Mondy R-band optical observations
  9. GRB 250918A: SVOM/GRM observation
  10. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  11. GRB 250919A: Swift-XRT afterglow detection
  12. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  13. GRB 250919A: SVOM/GRM observation of a very bright GRB
  14. EP250919a: Einstein Probe detection of an X-ray transient
  15. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart
  16. GRB 250916A: Fermi GBM Observation
  17. GRB 250916A: KAIT optical observations
  18. GRB 250916A: NuSTAR detection of the prompt emission
  19. GRB 250916A: further SAO RAS optical observations
  20. GRB 250917B: Swift/UVOT Upper Limits
  21. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  22. GRB 250916A: Swift-XRT observations
  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: GOTO optical counterpart candidate
  28. EP250827b: VLA Observations
  29. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  30. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  31. GRB 250912A: VLT observations
  32. GRB 250912A:SVOM/VT optical upper limit
  33. GRB 250912A: LCO optical upper limit
  34. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  35. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  36. GRB 250910B: SVOM/GRM observation
  37. EP250911a: SVOM/VT optical observation
  38. GRB 250911A: MASTER optical counterpart observations
  39. EP250911a: SAO RAS optical observations
  40. EP250911a: Swift-XRT observations
  41. EP250911a: Optical detection with Kinder observations
  42. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  43. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  44. EP250911a: COLIBRÍ optical observations
  45. EP250911a: LCO optical counterpart discovery
  46. GRB 250911A: COLIBRÍ optical counterpart candidate
  47. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  48. GRB 250910A: SVOM/VT optical upper limit
  49. EP250908C: GROND observation of the fading optical counterpart
  50. GRB 250910A: LCO optical upper limit
  51. EP250908c: SVOM/VT optical observation
  52. EP250908c: VLT/FORS2 optical counterpart identification
  53. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  54. EP250908b: SVOM/VT optical candidate
  55. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  56. GRB 250903A: Swift-XRT afterglow detection
  57. EP250905a: Liverpool Telescope i-band upper limits
  58. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  59. EP250905a: Liverpool Telescope observations
  60. EP250905a: FTW one optical and multiple NIR counterpart candidates
  61. EP250905a: JinShan likely optical counterpart detection
  62. GRB 250905A: Swift/UVOT Upper Limits
  63. GRB250904A: Liverpool Telescope upper limits
  64. GRB 250903A: Swift/UVOT detection
  65. GRB 250905A: KAIT optical upper limit
  66. GRB 250904A: TRT optical counterpart detection
  67. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  68. GRB 250903A: Swift-XRT observations
  69. EP250903a: Swift-XRT observations
  70. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  71. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  72. GRB 250903A: EP-FXT counterpart detection
  73. GRB 250903A: LCO optical observation
  74. GRB 250903A: LCO optical afterglow detection
  75. GRB 250903A: SVOM/VT optical confirmation with VHF data
  76. EP250903a: SVOM/VT optical confirmation
  77. EP250901a: Mondy, Assy and SAO RAS optical limits
  78. Subject GRB 250903A: SVOM/MXT afterglow detection
  79. GRB 250903A: TRT optical counterpart detection
  80. GRB 250903A: SVOM detection of a burst
  81. EP250903a: TRT optical observations
  82. EP 250827B: Detection of supernova counterpart by LCO.
  83. EP/WXT01709201159: GOTO optical follow-up
  84. EP250827b / AT 2025wkm: TRT optical observations
  85. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  86. GRB 250902B: SVOM/GRM observation
  87. GRB 250901A: Swift/UVOT Upper Limit
  88. GRB 250902A: SVOM/GRM observation
  89. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  90. GRB 250901A: EP-FXT follow-up observation
  91. GRB 250901A: NOT optical observations
  92. GRB 250901A: SVOM/VT optical afterglow with VHF data
  93. GRB 250901A: LCO optical upper limit
  94. EP250827b: Swift observations of AT 2025wkm
  95. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  96. EP250831a: NOT optical observations and tentative afterglow candidate
  97. EP250827b: FTW Observations of AT 2025wkm
  98. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  99. EP250901a: Mephisto optical upper limits
  100. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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