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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

14248 results found.

  1. Konus-Wind detection of GRB 241021A
  2. GRB 241105A: Swift-XRT afterglow detection
  3. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  4. GRB 240511A: LCO upper limits
  5. GRB 241104A: NOT optical non-detection
  6. GRB 241105A: Fermi GBM Final Real-time Localization
  7. GRB 241104A: SVOM/GRM observation
  8. EP241104a: EP detection of GRB 241104A X-ray emission
  9. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  10. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  11. GRB 241104A: Fermi GBM Final Real-time Localization
  12. GRB 241030A: GRBAlpha detection
  13. EP241101a: EP-FXT observations update
  14. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  15. EP241101a: Possible detection of an optical counterpart with FTW
  16. EP241103a: Swift XRT detection and improved X-ray position
  17. EP241101a: OHP/T193 optical observations
  18. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  19. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  20. EP241103a: GSP optical upper limit
  21. EP241103a: an X-ray transient detected by Einstein Probe
  22. GRB 241029A: GRBAlpha detection
  23. EP241101a: BOOTES-7 optical upper limit
  24. EP241101a: EP-WXT detection of a fast X-ray transient
  25. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  26. EP241021a: Upper limit from Konus-Wind observations
  27. EP241021a: Liverpool Telescope optical follow-up observations
  28. GRB 241101A: Swift detection of a burst
  29. GRB 241030B: Montarrenti Observatory optical upper limit
  30. EP241026b: Liverpool Telescope optical follow-up
  31. EP241021a: AMI-LA radio detection
  32. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  33. GRB 241030B: Swift/UVOT Detection
  34. GRB 241029A: LCO optical detection
  35. GRB 241030B: SVOM/GRM observation
  36. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  37. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  38. GRB 241030B: BTA observations
  39. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  40. EP241021a: Swift-UVOT detection
  41. GRB241030B: GRANDMA/TAROT Upper Limit
  42. GRB 241030B: AKO Optical Afterglow Detection
  43. GRB 241030B: Nanshan/HMT optical afterglow detection
  44. GRB 241030B: SVOM/ECLAIRs detection of a burst
  45. Konus-Wind detection of GRB 241030A
  46. GRB 241030B: Swift detection of a burst
  47. GRB 241030B: Fermi GBM Final Real-time Localization
  48. GRB 241030A: Fermi-LAT detection
  49. GRB 240912A: radio detection with the VLA
  50. GRB 241030A: AKO Optical Afterglow Detection
  51. GRB 241030A: Swift/UVOT Detection
  52. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  53. GRB 241030A: SVOM/GRM observation
  54. EP241026b: EP-FXT follow-up observation
  55. GRB 241030A: Multiband optical detection with Mephisto
  56. GRB 241030A : MITSuME Akeno optical afterglow detection
  57. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  58. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  59. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  60. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  61. GRB 241030A: Fermi GBM Final Real-time Localization
  62. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  63. GRB 241029A: AKO Optical Afterglow Detection
  64. GRB 241029A: GOTO optical afterglow detection
  65. GRB 241029A: MASTER early optical counterpart detection
  66. GRB 241029A: TRT optical afterglow candidate detection
  67. GRB 241029A: SVOM/GRM observation
  68. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  69. GRB 241029A: Fermi GBM Final Real-time Localization
  70. EP241021a: Gemini-South detection of optical rebrightening
  71. GRB 241026A: the 100th GRB detected by GRBAlpha
  72. GRB 241026A: TNOT optical counterpart detection
  73. Konus-Wind detection of GRB 241025A
  74. GRB 241026A: GECAM detection
  75. GRB 241026A: SVOM/GRM observation
  76. GRB 241025A: Swift/UVOT Detection
  77. GRB 241026A: Las Cumbres optical detection
  78. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  79. EP241026b: EP detection of a fast X-ray transient
  80. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  81. GRB 241026A: Swift detection of a burst
  82. GRB 241026A: Fermi GBM Final Real-time Localization
  83. GRB241025A: 1.3m DFOT optical afterglow detection
  84. EP241021a: optical follow-up observations with Xinglong Observatory
  85. ​GRB 241025A: optical photometry from Konkoly
  86. GRB 241025A: COLIBRÍ Detection of the Afterglow
  87. GRB 241025C: Fermi GBM Detection
  88. GRB 241025C: Fermi GBM Final Localization
  89. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  90. GRB 241025B: Fermi GBM Final Localization
  91. EP241021a: Liverpool Telescope optical follow-up observations
  92. GRB 241025A: DDOTI Afterglow detection
  93. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  94. GRB 241025A: SVOM/GRM observation
  95. GRB 241025A: Fermi GBM Final Real-time Localization
  96. GRB 241025A: Swift detection of a burst with an optical counterpart
  97. GRB 241001A: ATCA radio observations
  98. GRB 241024B: Fermi GBM Final Localization
  99. EP241021a: No Detection in Fermi-GBM Observation
  100. GRB 241010A: VIRT Optical Upper Limit

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