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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26719 results found.

  1. GRB 250725A: Swift/UVOT Upper Limits
  2. GRB 250725A: SVOM/VT optical candidate
  3. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  4. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  6. GRB 250725A: Enhanced Swift-XRT position
  7. GRB 250725A: Swift detection of a burst
  8. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  9. SVOM J195836+32283 is not a real source
  10. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  11. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  12. GRB 250721A: Fermi GBM Observation
  13. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  14. GRB 250721A: Swift-XRT observations
  15. GRB 250713A : SVOM/ECLAIRs refined analysis
  16. GRB 250717B: SVOM/GRM observation
  17. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  18. GRB 250717B: COLIBRÍ optical upper limit
  19. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  20. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  21. GRB 270713A: Kitab and AbAO Optical Observations
  22. GRB 250717B: Fermi GBM Observation
  23. GRB 250716A: Swift-XRT afterglow detection
  24. GRB 250716A: Fermi GBM Observation
  25. GRB 250714A: SVOM/GRM observation
  26. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  27. GRB 250713A: Mephisto optical upper limits
  28. GRB 250713A: SVOM/VT optical upper limit
  29. GRB 250713A: NOT optical upper limits
  30. GRB 250713A: OHP/T193 upper limit
  31. GRB 250713A: SVOM/C-GFT upper limit
  32. GRB 250706B/C: 7DT Follow-up Observations
  33. GRB 250713A: Swift-XRT observations
  34. GRB 250713A: EP-FXT counterpart detection
  35. EP250711a: COLIBRÍ continuous optical observations
  36. GRB 250706A: Swift-BAT refined analysis
  37. GRB 250713A: JinShan optical upper limits
  38. GRB 250713A: SVOM detection of a long burst
  39. GRB 250711A: DDOTI Optical Upper Limit
  40. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  41. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  42. GRB 250711A: SVOM/GRM observation
  43. EP250711a: NOT optical counterpart candidate
  44. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  45. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  46. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  47. GRB 250704A: GRANDMA observations
  48. GRB 250704A: SVOM/ECLAIRs refined analysis
  49. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  50. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  51. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  52. GRB 250702B,D,E / EP250702a: ALMA detection
  53. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  55. IceCube-250708A: No Candidates from WINTER
  56. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  57. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  58. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  59. EP250704a/GRB 250704B: 10 GHz VLA detection
  60. The EP-WXT trigger 01709181970 is likely a flaring star
  61. IceCube-250706A: No Candidates from WINTER
  62. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  63. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  64. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  65. EP250704a/GRB250704B : HCT optical and NIR upper limits
  66. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  67. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  68. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  69. GRB 250702F: radio detection with the VLA
  70. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  71. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  72. GRB 250706B/C: Fermi-LAT detection
  73. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  74. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  75. GRB 250706B: Swift/UVOT Detection
  76. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  77. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  78. GRB 250702F: GRANDMA observations
  79. GRB 250706A: Swift-XRT refined Analysis
  80. GRB 250706B: refined SVOM/MXT data analysis
  81. GRB 250706A: Swift/UVOT Upper Limits
  82. GRB 250706B: REM optical observations
  83. GRB 250706A: REM optical/NIR observations
  84. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  85. IceCube-250416A: DDOTI Optical Upper Limit
  86. IceCube-250706A: COLIBRÍ optical upper limits
  87. GRB 250706A: JinShan optical upper limits
  88. GRB 250706A: SAO RAS optical observations
  89. EP250704A: NOWT Detection
  90. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  91. The EP-WXT trigger 01709181580 is likely a flaring star
  92. GRB250706B: Swift-XRT counterpart detection
  93. GRB 250706B: iTelescope optical observations
  94. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  95. GRB 250706B: SVOM/VT optical observation
  96. GRB 250706B: TRT bright optical counterpart detection
  97. GRB 250706A: GROWTH-India Telescope optical upper limit
  98. GRB 250706B: SVOM detection of a long burst
  99. GRB 250706A: Swift detection of a burst
  100. GRB 250704B: Swift-XRT refined Analysis

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