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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"

26686 results found.

  1. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  2. GRB 250814A: Further GRAWITA TNG NIR observations
  3. GRB 250818B: Swift-XRT afterglow detection
  4. GRB 250818B: SVOM detection of a short burst
  5. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  6. GRB 250818A: Swift detection of a burst
  7. sb25081602: Swift-XRT observations
  8. GRB 250816A: SVOM/GRM observation of a short burst
  9. SVOM/sb25081602: detection of a likely X-ray transient
  10. GRB 250813B: Liverpool Telescope optical upper limits
  11. GRB 250814A: Further COLIBRÍ optical upper limit
  12. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  13. GRB 250814A: GRAWITA TNG NIR observations
  14. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  15. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  16. GRB250814A: TRT optical upper limits
  17. GRB 250814B: SVOM/GRM observation
  18. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  19. GRB 250813B: SVOM/GRM observation
  20. GRB 250814A: P200/WIRC observations of the afterglow candidate
  21. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  22. GRB 250814A: KAIT optical upper limit
  23. GRB 250814A: Swift-XRT refined Analysis
  24. GRB 240814A: Fermi GBM Observation
  25. GRB 250814A: Possible afterglow candidate from P200/WIRC
  26. GRB 250813B: Fermi GBM Observation
  27. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  28. GRB 250814A: J-band upper limit from WINTER
  29. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 250813B: NOT observations of the optical afterglow
  31. Subject GRB 250813B: SVOM/MXT refined analysis
  32. GRB 250814A: COLIBRÍ optical upper limit
  33. GRB 250813A: AstroSat CZTI detection
  34. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  35. GRB 250814A: DDOTI Optical Upper Limit
  36. GRB 250813B: EP-FXT counterpart detection
  37. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  38. GRB 250813B: Swift-XRT afterglow detection
  39. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  40. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  41. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  42. GRB 250813B: SVOM detection of a bright long burst
  43. EP250812a: Nickel optical upper limit
  44. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  45. EP250812a: NOT, NTT, and GS observations
  46. GRB 250812A: Swift/UVOT Detection
  47. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  48. EP250812a: Liverpool Telescope upper limits
  49. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  50. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  51. EP 250812a: GOTO optical upper limit
  52. GRB 250812A: Kilonova-Catcher optical afterglow detection
  53. EP250812a: Swift-XRT counterpart detection
  54. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  55. EP250812a: Einstein Probe detection of an X-ray transient
  56. GRB 250812A: Swift-XRT afterglow detection
  57. GRB 250812A: TRT likely optical counterpart detection
  58. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB 250812A: SVOM detection of a faint long burst
  60. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  61. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  62. GRB 250809A: Swift/UVOT Detection
  63. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  64. Corrected Swift-XRT Refined Analysis of GRB 250809A
  65. GRB 250809A: Swift-XRT refined Analysis
  66. EP250807a: EP-FXT follow-up observation upper limit
  67. GRB 250809A: LCOGT Optical Upper Limits
  68. GRB 250702B: Chandra X-ray Detection
  69. GRB 250808A: VLT X-shooter candidate counterpart
  70. GRB 250809A: Swift detection of a gamma ray burst
  71. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. GRB 250808A: Fermi GBM Observation
  73. GRB 250808A: Swift-XRT candidate counterpart detection
  74. GRB 250808A: SVOM detection of a long burst
  75. Konus-Wind detection of GRB 250807A
  76. GRB 250807B: Swift/UVOT Detection
  77. GRB 250807B: Kilonova-Catcher optical afterglow detection
  78. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 250807A: Swift/UVOT Detection
  80. GRB 250807A: Swift-XRT refined Analysis
  81. GRB 250806A: SVOM/ECLAIRs refined analysis
  82. EP250807a: NTT z-band optical upper limit
  83. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  84. GRB 250807A: SVOM/GRM observation
  85. GRB 250807A: AstroSat CZTI detection of bright long burst
  86. GRB 250807B: Swift-XRT refined Analysis
  87. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  88. EP250807a: EP-WXT detection of a fast X-ray transient
  89. EP 250807.979: GOTO optical upper limit
  90. EP250807a: COLIBRÍ optical upper limit
  91. GRB 250807B: Enhanced Swift-XRT position
  92. GRB 250807A: Enhanced Swift-XRT position
  93. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 250807B: Swift detection of a burst with an optical counterpart.
  95. GRB 250805A: Kilonova-Catcher optical upper limits
  96. GRB 250805A: Swift/UVOT Upper Limits
  97. GRB 250806A: Swift/UVOT U-band detection
  98. EP250806a: Liverpool telescope optical upper limit
  99. GRB 250807A: Swift detection of a burst with an optical counterpart
  100. IceCube Alert 250804.84: Global MASTER-Net observations report

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