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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. IPN triangulation of GRB 240603A
  2. GRB 240605B: Fermi GBM Final Real-time Localization
  3. GRB 240604A: Fermi GBM Final Localization
  4. GRB 240605A: Fermi GBM Final Real-time Localization
  5. GRB 240604A: GECAM detection of a long burst
  6. GRB 240529A: SAO RAS optical observations
  7. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  8. Fermi GRB 240603C: Global MASTER-Net observations report
  9. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  10. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  11. GRB 240603A: Fermi GBM Final Localization
  12. GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
  13. GRB 240603C: Fermi GBM Final Real-time Localization
  14. Swift Trigger 1232465: consistent with noise
  15. GRB 240603B: Swift detection of a possible burst
  16. GRB 240529A: MASTER prompt OT detection
  17. GRB 240603A: GECAM detection of a short burst
  18. GRB 240529A: continued SAO RAS optical observations
  19. Fermi GRB 240602A: Global MASTER-Net observations report
  20. GRB 240529A: OSN optical detection
  21. The EP-WXT source triggered on June 1st is likely a flaring star
  22. GRB 240529A: further SAO RAS optical observations
  23. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  24. GRB 240602A: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
  26. Swift Trigger 1232465 is not a GRB
  27. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  28. LIGO/Virgo/KAGRA S240530a: Updated Sky localization
  29. LXT 240528A: GSP optical upper limit
  30. GRB 240529A: 1.3m DFOT Optical observations
  31. LIGO/Virgo/KAGRA S240527en: Updated Sky localization
  32. LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate
  33. GRB 240531A: AstroSat CZTI detection of a short burst
  34. GRB 240529A : Mondy optical observations
  35. Konus-Wind detection of GRB 240529A
  36. IPN triangulation of the initial episode of GRB 240529A
  37. GRB 240529A: SAO RAS optical observations
  38. LIGO/Virgo/KAGRA S240531bp: Updated Sky localization
  39. LIGO/Virgo/KAGRA S240531bp: Identification of a GW compact binary merger candidate
  40. GRB 240529A: MAAO 0.7m telescope optical afterglow detection
  41. GRB 240529A: Insight-HXMT/HE detection
  42. GRB 240529A: optical photometry from Konkoly
  43. GRB 240529A: GROWTH-India optical follow-up
  44. GRB 240529A: T193/MISTRAL observations
  45. GRB 240529A: Redshift from GTC/OSIRIS+
  46. GRB 240529A: AKO Optical Afterglow Detection
  47. LIGO/Virgo/KAGRA S240530a: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S240527fv: Upper limits from Swift/BAT-GUANO
  49. LIGO/Virgo/KAGRA S240525p: Upper limits from Swift/BAT-GUANO
  50. GRB 240529A: J-band detections with WINTER
  51. GRB 240529A: Skynet Optical Observations
  52. LXT 240528A: LEIA detection of a fast X-ray transient
  53. GRB 240529A: Swift-BAT refined analysis
  54. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  55. GRB 240529A: Swift-XRT refined Analysis
  56. GRB240529A: BOOTES-6/DPRT optical detection
  57. GRB 240529A: Swift/UVOT Detection
  58. GRB 240529A: NOT optical observations
  59. GRB 240529A: AstroSat CZTI detection
  60. GRB 240529A: GOTO optical afterglow detection
  61. GRB 240527B: Swift-XRT afterglow detection
  62. GRB 240529A: Enhanced Swift-XRT position
  63. GRB 240529A: Swift detection of a burst with an optical counterpart
  64. Swift GRB240529.12: Global MASTER-Net observations report
  65. LIGO/Virgo/KAGRA S240527fv: Updated Sky localization
  66. GRB 240527B: Fermi GBM Observation
  67. Fermi GRB 240527A: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate
  69. GRB 240527B: Fermi-LAT detection
  70. LAT GRB240527.59: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S240527en: Identification of a GW compact binary merger candidate
  72. Fermi GRB 240527B: Global MASTER-Net observations report
  73. GRB 240527B: Fermi GBM Final Localization
  74. GRB 240527B: BALROG localization (Fermi Trigger 738511436 / GRB 240527586)
  75. GRB 240527A: Fermi GBM Final Real-time Localization
  76. GRB 240523A: Swift-BAT refined analysis
  77. Fermi trigger No 738348224: Global MASTER-Net observations report
  78. Fermi trigger No 738330463: Global MASTER-Net observations report
  79. LIGO/Virgo/KAGRA S240525p: Updated Sky localization
  80. LIGO/Virgo/KAGRA S240525p: Identification of a GW compact binary merger candidate
  81. GRB 240523A: Swift-XRT refined Analysis
  82. GRB 240523A: Enhanced Swift-XRT position
  83. GRB 240523A: Swift detection of a burst
  84. GRB 240521B: Fermi GBM Observation
  85. Fermi GBM Sub-Threshold Detection of GRB 240516B
  86. GRB 240513A: Swift-XRT afterglow detection
  87. GRB 240521B: Swift/BAT-GUANO arcminute localization of a long burst
  88. Fermi trigger No 737996942: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S240520cv: Updated Sky localization and EM Bright Classification
  90. EP240518a: GSP optical upper limit
  91. GRB 240521A: GECAM-B detection of a long burst
  92. GRB 240516B: AstroSat CZTI detection
  93. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  94. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  95. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  96. LIGO/Virgo/KAGRA S240520cv: Identification of a GW compact binary merger candidate
  97. IceCube-Cascade 240518A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 240514B: VZLUSAT-2 detection
  99. GRB 240504A: VZLUSAT-2 detection
  100. GRB 240502A: VZLUSAT-2 detection

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