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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. GRB240529A: VIRT optical transient detection
  2. GRB 240727B: Swift ToO observations
  3. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  4. GRB 240726A: SVOM/GRM observation
  5. GRB 240727B: AstroSat CZTI detection
  6. GRB 240726B: AstroSat CZTI detection of a short burst
  7. GRB240727A: Skynet Optical Afterglow Observations
  8. GRB 240727A: TRT optical afterglow detection
  9. GRB 240727A: KAIT Optical Afterglow Candidate
  10. GRB 240727A: Swift detection of a burst
  11. GRB 240726A: AstroSat CZTI detection of a short burst
  12. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 240726A: Fermi GBM Final Real-time Localization
  14. Fermi-LAT gamma-ray observations of IceCube-240725A
  15. IceCube Alert 240725.22: Global MASTER-Net observations report
  16. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  17. Swift Trigger 1244778 is not a GRB
  18. Swift GRB240725.11: Global MASTER-Net observations report
  19. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  20. GRB 240720A: Swift-BAT refined analysis
  21. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  22. Fermi trigger No 743418632: Global MASTER-Net observations report
  23. Fermi trigger No 743315411: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  26. Fermi trigger No 743345551: Global MASTER-Net observations report
  27. Fermi-LAT gamma-ray observations of IceCube-240721A
  28. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  29. Fermi trigger No 743219692: Global MASTER-Net observations report
  30. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  31. IceCube Alert 240721.68: Global MASTER-Net observations report
  32. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  33. GRB 240720B: SVOM/GRM observation
  34. GRB 240721A: Fermi GBM Final Real-time Localization
  35. GRB 240720B: AstroSat CZTI detection of a short burst
  36. Fermi GRB 240720A: Global MASTER-Net observations report
  37. GRB 240720A: AstroSat CZTI detection
  38. GRB 240720A: Fermi GBM observation
  39. GRB 240720A: Swift detection of a burst
  40. Swift GRB240720.02: Global MASTER-Net observations report
  41. Konus-Wind detection of GRB 240718A
  42. GRB 240713A: SVOM/GRM observation
  43. Fermi GRB 240718A: Global MASTER-Net observations report
  44. LAT GRB240718.27: Global MASTER-Net observations report
  45. GRB 240718A: Fermi GBM Observation
  46. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  47. GRB 240718A: Fermi-LAT Detection
  48. GRB 240718A: SVOM/GRM observation
  49. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  50. GRB 240718A: Fermi GBM Final Real-time Localization
  51. GRB 240712A: Swift-BAT refined analysis
  52. GRB 240716A: GECAM-B detection of a long burst
  53. SVOM/GRM In-Flight Trigger of GRB 240716A
  54. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  55. GRB 240713A: 2.2m CAHA optical limit
  56. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  57. GRB 240715A: Swift/UVOT observations of the XRT sources.
  58. GRB 240715A: Swift-XRT observations
  59. GRB240713A: Swift/UVOT Upper LImits
  60. EP240708a: X-ray follow-up observations with Swift/XRT
  61. GRB 240715A: GECAM-C detection of a short burst
  62. Konus-Wind detection of GRB 240715A
  63. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  64. GRB 240713A: Swift-XRT observations
  65. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  66. GRB 240712A: Swift-XRT refined Analysis
  67. SVOM/GRM In-Flight Trigger of GRB 240715A
  68. GRB 240713A: LAST optical upper limit
  69. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  70. GRB 240715A: Swift ToO observations
  71. Fermi GRB 240715A: Global MASTER-Net observations report
  72. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  73. GRB 240715A: Fermi GBM Observation
  74. GRB 240712A ATCA radio observations
  75. GRB240715A: GRANDMA Optical Upper Limits
  76. IPN triangulation of GRB 240715A (short)
  77. GW s240422ed: Swift UVOT follow-up
  78. GRB 240712A: Swift/UVOT Upper Limits
  79. EP-WXT flaring star and the optical flaring activity during its decay phase
  80. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  81. The EP-WXT source triggered on July 14th is likely a flaring star
  82. GRB 240715A: Fermi GBM Final Real-time Localization
  83. GRB 240713A: Tiled Swift observations
  84. GRB 240713A: J-band upper limit from WINTER
  85. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  86. GRB 240713A: JinShan optical upper limits
  87. GRB 240713A: OHP/T120 optical upper limit
  88. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  89. GRB240713A: X-ray follow-up observation with EP-FXT
  90. GRB 240713B: AstroSat CZTI detection of a long burst
  91. GRB240713A: Optical upper limit with Kinder observations
  92. Fermi Sub-threshold Observation of GRB240713A
  93. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  94. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  95. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  96. EP240708a: GSP optical upper limit
  97. GRB 240712A: Swift detection of a burst
  98. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  99. GRB 240711A: Fermi GBM Final Real-time Localization
  100. Fermi trigger No 742405878: Global MASTER-Net observations report

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