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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"

14824 results found.

  1. GRB 240519A: GRBAlpha detection
  2. GRB 240519A: AstroSat CZTI detection
  3. EP240518a: possibly identified with a flare star by EP-FXT
  4. EP240518a: EP-WXT detection of a new X-ray transient
  5. IPN triangulation of GRB 240514B (short)
  6. GRB 240517A: Fermi GBM Final Real-time Localization
  7. Konus-Wind detection of GRB 240513A
  8. GRB 240516A: AstroSat CZTI detection
  9. GRB 240516A: Swift-XRT refined Analysis
  10. GRB 240514E: A possible candidate BD-21 1074
  11. GRB 240511A: Observations from GTC/OSIRIS+
  12. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  13. GRB 240516A: Swift detection of a burst
  14. GRB 240511A: radio detection of afterglow candidate
  15. GRB 240514E: MAXI/GSC detection of a probable afterglow
  16. GRB 240514B: GRBAlpha detection
  17. GRB 240514B: Fermi GBM Detection
  18. GRB 240514D: AstroSat CZTI detection
  19. GRB 240514C: Fermi GBM Final Real-time Localization
  20. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  21. GRB 240514B: Fermi GBM Final Real-time Localization
  22. GRB 240514A: Fermi GBM Final Real-time Localization
  23. GRB 240513A: Fermi-LAT detection
  24. GRB 240513B: Fermi GBM Final Real-time Localization
  25. GRB 240513A: AstroSat CZTI detection
  26. GRB 240511A : MITSuME Akeno optical upper limits
  27. GRB 240511A: optical afterglow detection from the NOT
  28. GRB 240511A: Swift detection of a burst
  29. GRB 240511A: Fermi GBM Final Real-time Localization
  30. EP240506a: Xinglong optical upper limit
  31. EP240506a: Archival radio searching
  32. EP240506a: BOOTES Network optical upper limit
  33. IPN triangulation of GRB 240504A
  34. EP240506a: EP-WXT detection of a new fast X-ray transient
  35. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  36. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  37. GRB 240503A: AstroSat CZTI detection
  38. GRB 240504A: Fermi GBM Final Real-time Localization
  39. GRB 240502C: Fermi GBM Final Localization
  40. GRB 240501B: GRBAlpha detection
  41. GRB 240430A: GRBAlpha detection
  42. GRB 240502B: Fermi GBM Final Real-time Localization
  43. GRB 240502A: Fermi GBM Final Real-time Localization
  44. GRB 240426A: VZLUSAT-2 detection
  45. GRB 240425A: VZLUSAT-2 detection
  46. GRB240430A: Fermi GBM Final Localization
  47. GRB 240501B: AstroSat CZTI detection
  48. GRB 240501A: Fermi GBM Final Real-time Localization
  49. GRB 240408B: VZLUSAT-2 detection
  50. GRB 240407A: VZLUSAT-2 detection
  51. X-ray transient EP240414a: Detection of associated supernova
  52. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  53. GRB 240425A: GRBAlpha detection
  54. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  55. GRB 240429A: Fermi GBM Final Real-time Localization
  56. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  57. LIGO/Virgo/KAGRA S240429an: Retraction of GW compact binary merger candidate
  58. GRB 240428A: Fermi GBM Final Real-time Localization
  59. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  60. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  61. EP240426b: AST3-2 optical upper limit
  62. EP240426b: EP-WXT detection of a new fast X-ray transient
  63. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  64. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  65. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  66. GRB 240426A: AstroSat CZTI detection
  67. EP240426a: YAHPT optical upper limit
  68. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  69. GRB 240414A: NOEMA detection
  70. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  71. EP240426a: GMG optical upper limit
  72. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  73. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  74. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  75. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  76. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  77. GRB 240425A: Fermi GBM Final Real-time Localization
  78. GRB 240422A: Glowbug gamma-ray detection
  79. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  80. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  81. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  82. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  83. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  84. GRB 240421B: GRBAlpha detection
  85. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  86. LXT240402A/GRB240402B: Chandra X-ray detection
  87. GRB 240419A: Possible ATCA radio detection
  88. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  89. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  90. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  91. GRB 240421A: Glowbug gamma-ray detection
  92. GRB 240414A: radio detection with the VLA
  93. GRB 240414A: LBT optical detection
  94. GRB 240419B : MITSuME Akeno optical upper limits
  95. GRB 240421B: AstroSat CZTI detection
  96. GRB 240422A: Fermi GBM Final Real-time Localization
  97. GRB240421B: BOOTES-5/JGT optical upper limit
  98. EP240417a: no counterpart detection by SOAR
  99. EP240420a: TNT upper limit to its optical counterpart
  100. EP240420a: Xinglong decaying optical counterpart

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