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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"

27124 results found.

  1. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  2. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  3. EP250821a: Einstein Probe detection of an X-ray transient
  4. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  5. LIGO/Virgo/KAGRA S250818k: Pan-STARRS grizy-band imaging and photometry of AT2025ulz
  6. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  7. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  8. GRB 250814A: Swift/UVOT Upper Limits
  9. GRB 250813B: Swift/UVOT Upper Limit
  10. IPN triangulation of GRB 250816A (short)
  11. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  12. GRB 250818B: Kilonova-Catcher optical afterglow detection
  13. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  14. GRB 250818B: Liverpool Telescope optical detections
  15. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  16. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  17. GRB 250818B: Swift/UVOT Detection
  18. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  19. GRB 250820A: Fermi GBM Final Real-time Localization
  20. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  21. Fermi GRB 250816A: Global MASTER-Net observations report
  22. Swift GRB 250818A: Global MASTER-Net observations report
  23. GRB 250818B: NOT optical observations
  24. GRB 250818A: Swift-XRT refined Analysis
  25. GRB 250818B: EP-FXT counterpart detection
  26. GRB 250818A: Swift-BAT refined analysis
  27. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  28. GRB 250818C: Fermi GBM Final Real-time Localization
  29. Fermi trigger No 776849714: Global MASTER-Net observations report
  30. GRB 250818B: KAIT optical observations
  31. GRB 250818A: Swift/UVOT Upper Limits
  32. LIGO/Virgo/KAGRA S250818k: Candidates from the Zwicky Transient Facility
  33. GRB 250813B: SVOM/ECLAIRs refined analysis
  34. GRB 250818A: Fermi GBM Observation
  35. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  36. GRB 250818B: SVOM/VT optical observation
  37. GRB 250814A: Further GRAWITA TNG NIR observations
  38. GRB 250818B: GOTO optical counterpart candidate
  39. GRB 250818B: SVOM detection of a short burst
  40. GRB 250818A: Swift detection of a burst
  41. GRB 250818A: Fermi GBM Final Real-time Localization
  42. sb25081602: Swift-XRT observations
  43. GRB 250816A: SVOM/GRM observation of a short burst
  44. SVOM/sb25081602: detection of a likely X-ray transient
  45. Fermi GRB 250814B: Global MASTER-Net observations report
  46. GRB 250816A: Fermi GBM Final Real-time Localization
  47. GRB 250814A: Swift-BAT refined analysis
  48. GRB 250815A: Fermi GBM Final Localization
  49. GRB 250813B: Liverpool Telescope optical upper limits
  50. GRB 250814A: Further COLIBRÍ optical upper limit
  51. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  52. GRB 250814A: GRAWITA TNG NIR observations
  53. GRB 250812A: SVOM/VT optical continued observation
  54. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  55. GRB250814A: TRT optical upper limits
  56. GRB 250814B: SVOM/GRM observation
  57. GRB 250814C: SVOM/GRM observation of a short burst
  58. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  59. GRB 250813B: SVOM/GRM observation
  60. GRB 250814A: P200/WIRC observations of the afterglow candidate
  61. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  62. GRB 250814A: Swift-XRT refined Analysis
  63. GRB 240814A: Fermi GBM Observation
  64. GRB 250814A: Possible afterglow candidate from P200/WIRC
  65. GRB 250813B: Fermi GBM Observation
  66. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  67. Fermi trigger No 776818276: Global MASTER-Net observations report
  68. Swift GRB250814.32: Global MASTER-Net observations report
  69. GRB 250814A: J-band upper limit from WINTER
  70. GRB 250813B: NOT observations of the optical afterglow
  71. GRB 250813B: SVOM/VT optical observations
  72. Subject GRB 250813B: SVOM/MXT refined analysis
  73. GRB 250814A: COLIBRÍ optical upper limit
  74. GRB 250814B: Fermi GBM Final Real-time Localization
  75. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  76. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  77. GRB 250814A: DDOTI Optical Upper Limit
  78. GRB 250813B: EP-FXT counterpart detection
  79. GRB 250813B: Swift-XRT afterglow detection
  80. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  81. GRB 250814A: Fermi GBM Final Real-time Localization
  82. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 250813B: Ondrejov D50 fast decay
  84. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  85. GRB 250813B: SVOM detection of a bright long burst
  86. EP250812a: Nickel optical upper limit
  87. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  88. GRB 250812A: NTT spectroscopic redshift z = 2.57
  89. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  90. EP250812a: NOT, NTT, and GS observations
  91. GRB 250812A: Swift/UVOT Detection
  92. GRB 250813A: Fermi GBM Final Localization
  93. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  94. EP250812a: Liverpool Telescope upper limits
  95. EP250812a: SVOM/VT optical counterpart
  96. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  97. IceCube Alert 250813.14: Global MASTER-Net observations report
  98. GRB 250812A: EP-FXT counterpart detection
  99. GRB 250807B: Swift-BAT refined analysis
  100. EP 250812a: GOTO optical upper limit

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