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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"

11756 results found.

  1. GRB 240414A: LBT optical detection
  2. GRB 240415A: Swift-XRT refined Analysis
  3. GRB 240421B: AstroSat CZTI detection
  4. GRB240421B: BOOTES-5/JGT optical upper limit
  5. Fermi GRB 240421A: Global MASTER-Net observations report
  6. EP240417a: no counterpart detection by SOAR
  7. EP240420a: Xinglong decaying optical counterpart
  8. GRB 240421B: Swift detection of a burst
  9. EP240420a: Nanshan optical counterpart observations
  10. EP240420a: GWAC-F50A optical upper limit
  11. Fermi trigger No 735280430: Global MASTER-Net observations report
  12. IceCube Alert 240419.98: Global MASTER-Net observations report
  13. GRB 240419B: Swift-XRT refined Analysis
  14. GRB 240419A: Swift-XRT refined Analysis
  15. GRB 240418A: Swift-XRT refined Analysis
  16. GRB 240419B: Swift detection of a burst
  17. EP240417a: YAHPT Optical Upper Limits
  18. GRB240418A: YAHPT Upper Limits
  19. GRB 240419A: VLT optical afterglow detection
  20. GRB 240419A: Swift detection of a burst
  21. Swift GRB240418.85: Global MASTER-Net observations report
  22. GRB 240418A: Swift detection of a burst
  23. Fermi GRB 240417A: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  25. GRB 240414A: Glowbug gamma-ray detection
  26. EP240416a: EP-WXT detection of a fast X-ray transient
  27. GRB 240414A: AbAO optical upprer limit
  28. GRB 240415A: OHP/T193 optical observations
  29. GRB 240415A: SAO RAS optical observations
  30. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  31. GRB 240414A: Fermi GBM Observation
  32. Fermi GRB 240415A: Global MASTER-Net observations report
  33. GRB 240414B: Fermi GBM Final Real-time Localization
  34. GRB 240415A: Prompt Swift-XRT observations
  35. GRB 240414A: Swift-XRT refined Analysis
  36. GRB240414A : J-band upper limits from WINTER
  37. IPN triangulation of GRB 240410A
  38. Fermi-LAT gamma-ray observations of IceCube-240412A
  39. EP240413a: EP-WXT detection of a fast X-ray transient
  40. GRB 240414A: Swift detection of a burst
  41. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  42. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  43. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  44. EP240408a: GROND detection of a candidate counterpart
  45. EP240408a: Swift follow-up observation
  46. EP240408a: EP-WXT detection of a fast X-ray transient
  47. GRB 240408B: AstroSat CZTI detection
  48. Fermi GRB 240407A: Global MASTER-Net observations report
  49. Fermi-LAT gamma-ray observations of IceCube-240327B
  50. Fermi-LAT gamma-ray observations of IceCube-240327A
  51. GRB 240331A: GRBAlpha detection
  52. Konus-Wind detection of LXT 240402A/GRB 240402B
  53. LXT 240402A: MASTER optical observations with AGN in error-box
  54. Fermi GRB 240402A: Global MASTER-Net observations report
  55. X-ray transient EP240331a: Kinder optical upper limits
  56. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  57. EP240331A: MASTER optical observations
  58. X-ray transient EP20240331a: MeerLICHT optical upper limits
  59. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 240324A: AstroSat CZTI detection of a short burst
  61. GRB 240331A: AstroSat CZTI detection
  62. GRB 240329A: AstroSat CZTI detection
  63. X-ray transient EP240315a: continued ATCA monitoring
  64. X-ray transient EP240315a: e-MERLIN radio observations
  65. GRB 240320A: Glowbug gamma-ray detection
  66. Fermi GRB 240320A: Global MASTER-Net observations report
  67. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  68. Fermi trigger No 732657380: Global MASTER-Net observations report
  69. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  70. X-ray transient EP240315a: ATCA detection of radio counterpart
  71. GRB 240320A: Fermi GBM Final Real-time Localization
  72. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  73. X-ray transient EP 240315a: Chandra observations
  74. GRB 240317C: Glowbug gamma-ray detection
  75. X-ray transient EP240315a: PRIME near infrared detection
  76. Fermi GRB 240318A: Global MASTER-Net observations report
  77. GRB 240317A: AstroSat CZTI detection
  78. GRB 240315B: AstroSat CZTI detection
  79. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  80. Fermi GRB 240317B: Global MASTER-Net observations report
  81. Fermi trigger No 732299243: Global MASTER-Net observations report
  82. Fermi GRB 240314A: Global MASTER-Net observations report
  83. GRB 240312A: GECAM detection of a long burst
  84. GRB 240303C: VZLUSAT-2 detection
  85. Fermi trigger No 731839490: Global MASTER-Net observations report
  86. Fermi-LAT gamma-ray observations of IceCube-240307A
  87. Fermi GRB 240310A: Global MASTER-Net observations report
  88. GRB 240309A: MAXI/GSC detection
  89. Fermi trigger No 731571927: Global MASTER-Net observations report
  90. Konus-Wind detection of GRB 231118A
  91. GRB 240306A: AstroSat CZTI detection
  92. Fermi GRB 240306A: Global MASTER-Net observations report
  93. Fermi GRB 240305A: Global MASTER-Net observations report
  94. GRB 240306A: Swift/BAT-GUANO detection of a burst
  95. Fermi-LAT gamma-ray observations of IceCube-240229A
  96. GRB 240305C: AstroSat CZTI detection of a short burst
  97. Fermi GRB 240305C: Global MASTER-Net observations report
  98. Konus-Wind detection of GRB 240227A (short/hard)
  99. Swift Trigger 1218701: Yes, we triggered on Swift J151857.0-572147 again
  100. Swift Trigger 1218696: Another trigger on Swift J151857.0-572147

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