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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. Fermi GRB 240726A: Global MASTER-Net observations report
  2. GRB 240727A: Enhanced Swift-XRT position
  3. GRB 240727B: Fermi GBM Observation
  4. Swift GRB240727.16: Global MASTER-Net observations report
  5. GRB240529A: VIRT optical transient detection
  6. GRB 240727B: Swift ToO observations
  7. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  8. GRB 240726A: SVOM/GRM observation
  9. GRB 240727B: AstroSat CZTI detection
  10. GRB 240726B: AstroSat CZTI detection of a short burst
  11. GRB240727A: Skynet Optical Afterglow Observations
  12. GRB 240727A: TRT optical afterglow detection
  13. GRB 240727A: KAIT Optical Afterglow Candidate
  14. GRB 240727A: Swift detection of a burst
  15. GRB 240726A: AstroSat CZTI detection of a short burst
  16. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 240726A: Fermi GBM Final Real-time Localization
  18. Fermi-LAT gamma-ray observations of IceCube-240725A
  19. IceCube Alert 240725.22: Global MASTER-Net observations report
  20. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  21. Swift Trigger 1244778 is not a GRB
  22. Swift GRB240725.11: Global MASTER-Net observations report
  23. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  24. GRB 240720A: Swift-BAT refined analysis
  25. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  26. Fermi trigger No 743418632: Global MASTER-Net observations report
  27. Fermi trigger No 743315411: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  29. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  30. Fermi trigger No 743345551: Global MASTER-Net observations report
  31. Fermi-LAT gamma-ray observations of IceCube-240721A
  32. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  33. Fermi trigger No 743219692: Global MASTER-Net observations report
  34. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  35. IceCube Alert 240721.68: Global MASTER-Net observations report
  36. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  37. GRB 240720B: SVOM/GRM observation
  38. GRB 240721A: Fermi GBM Final Real-time Localization
  39. GRB 240720B: AstroSat CZTI detection of a short burst
  40. Fermi GRB 240720A: Global MASTER-Net observations report
  41. GRB 240720A: AstroSat CZTI detection
  42. GRB 240720A: Fermi GBM observation
  43. GRB 240720A: Swift detection of a burst
  44. Swift GRB240720.02: Global MASTER-Net observations report
  45. Konus-Wind detection of GRB 240718A
  46. GRB 240713A: SVOM/GRM observation
  47. Fermi GRB 240718A: Global MASTER-Net observations report
  48. LAT GRB240718.27: Global MASTER-Net observations report
  49. GRB 240718A: Fermi GBM Observation
  50. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  51. GRB 240718A: Fermi-LAT Detection
  52. GRB 240718A: SVOM/GRM observation
  53. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  54. GRB 240718A: Fermi GBM Final Real-time Localization
  55. GRB 240712A: Swift-BAT refined analysis
  56. GRB 240716A: GECAM-B detection of a long burst
  57. SVOM/GRM In-Flight Trigger of GRB 240716A
  58. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  59. GRB 240713A: 2.2m CAHA optical limit
  60. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  61. GRB 240715A: Swift/UVOT observations of the XRT sources.
  62. GRB 240715A: Swift-XRT observations
  63. GRB240713A: Swift/UVOT Upper LImits
  64. EP240708a: X-ray follow-up observations with Swift/XRT
  65. GRB 240715A: GECAM-C detection of a short burst
  66. Konus-Wind detection of GRB 240715A
  67. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  68. GRB 240713A: Swift-XRT observations
  69. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  70. GRB 240712A: Swift-XRT refined Analysis
  71. SVOM/GRM In-Flight Trigger of GRB 240715A
  72. GRB 240713A: LAST optical upper limit
  73. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  74. GRB 240715A: Swift ToO observations
  75. Fermi GRB 240715A: Global MASTER-Net observations report
  76. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  77. GRB 240715A: Fermi GBM Observation
  78. GRB 240712A ATCA radio observations
  79. GRB240715A: GRANDMA Optical Upper Limits
  80. IPN triangulation of GRB 240715A (short)
  81. GW s240422ed: Swift UVOT follow-up
  82. GRB 240712A: Swift/UVOT Upper Limits
  83. EP-WXT flaring star and the optical flaring activity during its decay phase
  84. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  85. The EP-WXT source triggered on July 14th is likely a flaring star
  86. GRB 240715A: Fermi GBM Final Real-time Localization
  87. GRB 240713A: Tiled Swift observations
  88. GRB 240713A: J-band upper limit from WINTER
  89. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  90. GRB 240713A: JinShan optical upper limits
  91. GRB 240713A: OHP/T120 optical upper limit
  92. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  93. GRB240713A: X-ray follow-up observation with EP-FXT
  94. GRB 240713B: AstroSat CZTI detection of a long burst
  95. GRB240713A: Optical upper limit with Kinder observations
  96. Fermi Sub-threshold Observation of GRB240713A
  97. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  98. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  99. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  100. EP240708a: GSP optical upper limit

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