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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"

28252 results found.

  1. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  2. LIGO/Virgo/KAGRA S250818k: WINTER J-band observations of AT 2025ulz
  3. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  4. GRB 250814A: Swift/UVOT Upper Limits
  5. GRB 250813B: Swift/UVOT Upper Limit
  6. IPN triangulation of GRB 250816A (short)
  7. IPN triangulation of GRB 250814C (short)
  8. IPN triangulation of GRB 250804B (short)
  9. GRB 250818B: Kilonova-Catcher optical afterglow detection
  10. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  11. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  12. LIGO/Virgo/KAGRA S250818k: Updated Sky localization and EM Bright Classification
  13. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  14. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  15. GRB 250818B: Swift/UVOT Detection
  16. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  17. GRB 250818B: SAO RAS optical observations
  18. GRB 250818A: Swift-XRT refined Analysis
  19. GRB 250818B: EP-FXT counterpart detection
  20. GRB 250818A: Swift-BAT refined analysis
  21. GRB 250818B: KAIT optical observations
  22. GRB 250818A: Swift/UVOT Upper Limits
  23. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  24. GRB 250818A: Enhanced Swift-XRT position
  25. GRB 250813B: SVOM/ECLAIRs refined analysis
  26. GRB 250818A: Fermi GBM Observation
  27. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  28. GRB 250814A: Further GRAWITA TNG NIR observations
  29. GRB 250818B: Swift-XRT afterglow detection
  30. GRB 250818B: SVOM detection of a short burst
  31. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  32. GRB 250818A: Swift detection of a burst
  33. sb25081602: Swift-XRT observations
  34. GRB 250816A: SVOM/GRM observation of a short burst
  35. GRB 250814A: Swift-BAT refined analysis
  36. GRB 250813B: Liverpool Telescope optical upper limits
  37. GRB 250814A: Further COLIBRÍ optical upper limit
  38. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  39. GRB 250814A: GRAWITA TNG NIR observations
  40. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  41. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  42. GRB250814A: TRT optical upper limits
  43. GRB 250814B: SVOM/GRM observation
  44. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  45. GRB 250813B: SVOM/GRM observation
  46. GRB 250814A: P200/WIRC observations of the afterglow candidate
  47. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  48. GRB 250814A: KAIT optical upper limit
  49. GRB 250814A: Swift-XRT refined Analysis
  50. GRB 240814A: Fermi GBM Observation
  51. GRB 250814A: Possible afterglow candidate from P200/WIRC
  52. GRB 250813B: Fermi GBM Observation
  53. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  54. GRB 250814A: J-band upper limit from WINTER
  55. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 250813B: NOT observations of the optical afterglow
  57. GRB 250814A: COLIBRÍ optical upper limit
  58. GRB 250813A: AstroSat CZTI detection
  59. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  60. GRB 250814A: DDOTI Optical Upper Limit
  61. GRB 250813B: EP-FXT counterpart detection
  62. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  63. GRB 250813B: Swift-XRT afterglow detection
  64. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  65. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  66. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  67. GRB 250813B: SVOM detection of a bright long burst
  68. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  69. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  70. EP250812a: Nickel optical upper limit
  71. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  72. EP250812a: NOT, NTT, and GS observations
  73. GRB 250812A: Swift/UVOT Detection
  74. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  75. EP250812a: Liverpool Telescope upper limits
  76. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  77. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  78. GRB 250812A: EP-FXT counterpart detection
  79. GRB 250807B: Swift-BAT refined analysis
  80. EP 250812a: GOTO optical upper limit
  81. GRB 250812A: Kilonova-Catcher optical afterglow detection
  82. EP250812a: Swift-XRT counterpart detection
  83. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  84. EP250812a: Einstein Probe detection of an X-ray transient
  85. GRB 250812A: Swift-XRT afterglow detection
  86. GRB 250812A: TRT likely optical counterpart detection
  87. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 250809A: Swift-BAT refined analysis
  89. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  90. GRB 250807A: Swift-BAT refined analysis
  91. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  92. GRB 250809A: Swift/UVOT Detection
  93. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  94. Corrected Swift-XRT Refined Analysis of GRB 250809A
  95. GRB 250809A: Swift-XRT refined Analysis
  96. GRB 250809A: LCOGT Optical Upper Limits
  97. GRB 250808A: VLT X-shooter candidate counterpart
  98. GRB 250809A: Swift detection of a gamma ray burst
  99. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. GRB 250808A: Fermi GBM Observation

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