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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"
  1. GRB 240615A: Swift ToO observations
  2. GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
  3. GRB 240615A: Fermi GBM Final Real-time Localization
  4. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  6. GRB 240603A: VZLUSAT-2 detection
  7. GRB 240612A: GRBAlpha detection
  8. GRB 240613A: Fermi GBM Final Real-time Localization
  9. Fermi GRB 240612B: Global MASTER-Net observations report
  10. Fermi GRB 240612A: Global MASTER-Net observations report
  11. GRB 240612B: Fermi GBM Final Real-time Localization
  12. GRB 240612A: Fermi GBM Final Real-time Localization
  13. GRB 240607A: GECAM detection of a bright long burst
  14. Fermi GRB 240611A: Global MASTER-Net observations report
  15. Konus-Wind detection of GRB 240607A
  16. GRB 240611A: Fermi GBM Final Real-time Localization
  17. EXO 0748-676: Swift-BAT refined analysis
  18. GRB240529A: 3.6m TNG NIR detection 8d after the burst
  19. GRB 240529A: LBT optical detection and late temporal decay
  20. GRB 240529A : MITSuME Akeno optical afterglow detection
  21. Trigger 1236151: Swift detection of EXO 0748-676
  22. Fermi GRB 240610A: Global MASTER-Net observations report
  23. GRB 240610A: Fermi GBM Final Real-time Localization
  24. IPN triangulation of GRB 240607A
  25. Fermi Gamma-ray Burst Monitor trigger 739632045/240609556 is not a GRB
  26. Fermi trigger No 739632045: Global MASTER-Net observations report
  27. Fermi GRB 240608A: Global MASTER-Net observations report
  28. Konus-Wind detection of GRB 240606B
  29. Fermi trigger No 739506569: Global MASTER-Net observations report
  30. GRB 240608A: Fermi GBM Final Real-time Localization
  31. Fermi GRB 240607A: Global MASTER-Net observations report
  32. GRB 240529A: NOEMA detection
  33. GRB 240607A: Fermi GBM Observation
  34. GRB 240606B: Fermi GBM Observation
  35. Swift Trigger 1235109: consistent with noise and not astrophysical
  36. GRB 240607A: AstroSat CZTI detection of bright long burst
  37. GRB 240607A: Fermi GBM detection of a very bright burst
  38. GRB 240529A: radio detection with AMI-LA
  39. GRB 240607A: BALROG localization (Fermi Trigger 739450879 / GRB 240607459)
  40. GRB 240607A: Fermi GBM Final Real-time Localization
  41. GRB 240606B: GECAM-B detection a long burst
  42. Fermi trigger No 739373591: Global MASTER-Net observations report
  43. GRB 240606B: Swift-XRT afterglow detection
  44. Swift GRB240606.15: Global MASTER-Net observations report
  45. GRB 240606B: Swift ToO observations
  46. GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
  47. Konus-Wind detection of GRB 240603A
  48. Swift Trigger 1235109: a possible GRB 240606A
  49. Fermi GRB 240604A: Global MASTER-Net observations report
  50. IPN triangulation of GRB 240531A (short)
  51. Fermi GRB 240605A: Global MASTER-Net observations report
  52. Fermi GRB 240605C: Global MASTER-Net observations report
  53. Fermi Gamma-ray Burst Monitor trigger 739290883/240605607 is not a GRB
  54. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  55. GRB 240605C: Fermi GBM Final Real-time Localization
  56. IPN triangulation of GRB 240603A
  57. GRB 240605B: Fermi GBM Final Real-time Localization
  58. GRB 240604A: Fermi GBM Final Localization
  59. GRB 240605A: Fermi GBM Final Real-time Localization
  60. GRB 240604A: GECAM detection of a long burst
  61. GRB 240529A: SAO RAS optical observations
  62. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  63. Fermi GRB 240603C: Global MASTER-Net observations report
  64. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  65. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  66. GRB 240603A: Fermi GBM Final Localization
  67. GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
  68. GRB 240603C: Fermi GBM Final Real-time Localization
  69. Swift Trigger 1232465: consistent with noise
  70. GRB 240603B: Swift detection of a possible burst
  71. GRB 240529A: MASTER prompt OT detection
  72. GRB 240603A: GECAM detection of a short burst
  73. GRB 240529A: continued SAO RAS optical observations
  74. Fermi GRB 240602A: Global MASTER-Net observations report
  75. GRB 240529A: OSN optical detection
  76. The EP-WXT source triggered on June 1st is likely a flaring star
  77. GRB 240529A: further SAO RAS optical observations
  78. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  79. GRB 240602A: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
  81. Swift Trigger 1232465 is not a GRB
  82. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  83. LIGO/Virgo/KAGRA S240530a: Updated Sky localization
  84. LXT 240528A: GSP optical upper limit
  85. GRB 240529A: 1.3m DFOT Optical observations
  86. LIGO/Virgo/KAGRA S240527en: Updated Sky localization
  87. LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate
  88. GRB 240531A: AstroSat CZTI detection of a short burst
  89. GRB 240529A : Mondy optical observations
  90. Konus-Wind detection of GRB 240529A
  91. IPN triangulation of the initial episode of GRB 240529A
  92. GRB 240529A: SAO RAS optical observations
  93. LIGO/Virgo/KAGRA S240531bp: Updated Sky localization
  94. LIGO/Virgo/KAGRA S240531bp: Identification of a GW compact binary merger candidate
  95. GRB 240529A: MAAO 0.7m telescope optical afterglow detection
  96. GRB 240529A: Insight-HXMT/HE detection
  97. GRB 240529A: optical photometry from Konkoly
  98. GRB 240529A: GROWTH-India optical follow-up
  99. GRB 240529A: T193/MISTRAL observations
  100. GRB 240529A: Redshift from GTC/OSIRIS+

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