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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"

14832 results found.

  1. EP241101a: OHP/T193 optical observations
  2. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  3. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  4. EP241103a: GSP optical upper limit
  5. EP241103a: an X-ray transient detected by Einstein Probe
  6. GRB 241029A: GRBAlpha detection
  7. EP241101a: BOOTES-7 optical upper limit
  8. EP241101a: EP-WXT detection of a fast X-ray transient
  9. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  10. EP241021a: Upper limit from Konus-Wind observations
  11. EP241021a: Liverpool Telescope optical follow-up observations
  12. GRB 241101A: Swift detection of a burst
  13. GRB 241030B: Montarrenti Observatory optical upper limit
  14. EP241026b: Liverpool Telescope optical follow-up
  15. EP241021a: AMI-LA radio detection
  16. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  17. GRB 241030B: Swift/UVOT Detection
  18. GRB 241029A: LCO optical detection
  19. GRB 241030B: SVOM/GRM observation
  20. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  21. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  22. GRB 241030B: BTA observations
  23. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  24. EP241021a: Swift-UVOT detection
  25. GRB241030B: GRANDMA/TAROT Upper Limit
  26. GRB 241030B: AKO Optical Afterglow Detection
  27. GRB 241030B: Nanshan/HMT optical afterglow detection
  28. GRB 241030B: SVOM/ECLAIRs detection of a burst
  29. Konus-Wind detection of GRB 241030A
  30. GRB 241030B: Swift detection of a burst
  31. GRB 241030B: Fermi GBM Final Real-time Localization
  32. GRB 241030A: Fermi-LAT detection
  33. GRB 240912A: radio detection with the VLA
  34. GRB 241030A: AKO Optical Afterglow Detection
  35. GRB 241030A: Swift/UVOT Detection
  36. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  37. GRB 241030A: SVOM/GRM observation
  38. EP241026b: EP-FXT follow-up observation
  39. GRB 241030A: Multiband optical detection with Mephisto
  40. GRB 241030A : MITSuME Akeno optical afterglow detection
  41. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  42. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  43. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  44. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  45. GRB 241030A: Fermi GBM Final Real-time Localization
  46. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  47. GRB 241029A: AKO Optical Afterglow Detection
  48. GRB 241029A: GOTO optical afterglow detection
  49. GRB 241029A: MASTER early optical counterpart detection
  50. GRB 241029A: TRT optical afterglow candidate detection
  51. GRB 241029A: SVOM/GRM observation
  52. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  53. GRB 241029A: Fermi GBM Final Real-time Localization
  54. EP241021a: Gemini-South detection of optical rebrightening
  55. GRB 241026A: the 100th GRB detected by GRBAlpha
  56. GRB 241026A: TNOT optical counterpart detection
  57. Konus-Wind detection of GRB 241025A
  58. GRB 241026A: GECAM detection
  59. GRB 241026A: SVOM/GRM observation
  60. GRB 241025A: Swift/UVOT Detection
  61. GRB 241026A: Las Cumbres optical detection
  62. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  63. EP241026b: EP detection of a fast X-ray transient
  64. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  65. GRB 241026A: Swift detection of a burst
  66. GRB 241026A: Fermi GBM Final Real-time Localization
  67. GRB241025A: 1.3m DFOT optical afterglow detection
  68. EP241021a: optical follow-up observations with Xinglong Observatory
  69. ​GRB 241025A: optical photometry from Konkoly
  70. GRB 241025A: COLIBRÍ Detection of the Afterglow
  71. GRB 241025C: Fermi GBM Detection
  72. GRB 241025C: Fermi GBM Final Localization
  73. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  74. GRB 241025B: Fermi GBM Final Localization
  75. EP241021a: Liverpool Telescope optical follow-up observations
  76. GRB 241025A: DDOTI Afterglow detection
  77. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  78. GRB 241025A: SVOM/GRM observation
  79. GRB 241025A: Fermi GBM Final Real-time Localization
  80. GRB 241025A: Swift detection of a burst with an optical counterpart
  81. GRB 241001A: ATCA radio observations
  82. GRB 241024B: Fermi GBM Final Localization
  83. EP241021a: No Detection in Fermi-GBM Observation
  84. GRB 241010A: VIRT Optical Upper Limit
  85. GRB 241024A: Fermi GBM Final Localisation
  86. EP241021a: VLT/FORS2 redshift z = 0.75
  87. EP241021a: EP-FXT follow-up observation update
  88. EP241021a: Optical counterpart observations with the Liverpool Telescope
  89. EP241021a: 1.3m DFOT Optical observations
  90. EP241021a: NOT likely optical counterpart
  91. GRB241017A: 1.3m DFOT optical upper limit
  92. GRB 241018A: 1.3m DFOT Optical upper limit
  93. GRB 241018A: EP-FXT afterglow detection
  94. EP241021a: EP detection of a fast X-ray transient
  95. Konus-Wind detection of GRB 241018A
  96. GRB 241018A: SVOM/GRM observation
  97. GRB 241018A: BOOTES-4/MET optical upper limit
  98. GRB 241018A: Mondy optical upper limit
  99. GRB 241006A: VIRT Optical Upper Limit
  100. GRB 240727A: VIRT Optical Upper Limit

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