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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-LAT gamma-ray observations of IceCube-240725A
  2. IceCube Alert 240725.22: Global MASTER-Net observations report
  3. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  4. Swift Trigger 1244778 is not a GRB
  5. Swift GRB240725.11: Global MASTER-Net observations report
  6. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  7. GRB 240720A: Swift-BAT refined analysis
  8. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  9. Fermi trigger No 743418632: Global MASTER-Net observations report
  10. Fermi trigger No 743315411: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  12. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  13. Fermi trigger No 743345551: Global MASTER-Net observations report
  14. Fermi-LAT gamma-ray observations of IceCube-240721A
  15. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  16. Fermi trigger No 743219692: Global MASTER-Net observations report
  17. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube Alert 240721.68: Global MASTER-Net observations report
  19. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  20. GRB 240720B: SVOM/GRM observation
  21. GRB 240721A: Fermi GBM Final Real-time Localization
  22. GRB 240720B: AstroSat CZTI detection of a short burst
  23. Fermi GRB 240720A: Global MASTER-Net observations report
  24. GRB 240720A: AstroSat CZTI detection
  25. GRB 240720A: Fermi GBM observation
  26. GRB 240720A: Swift detection of a burst
  27. Swift GRB240720.02: Global MASTER-Net observations report
  28. Konus-Wind detection of GRB 240718A
  29. GRB 240713A: SVOM/GRM observation
  30. Fermi GRB 240718A: Global MASTER-Net observations report
  31. LAT GRB240718.27: Global MASTER-Net observations report
  32. GRB 240718A: Fermi GBM Observation
  33. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  34. GRB 240718A: Fermi-LAT Detection
  35. GRB 240718A: SVOM/GRM observation
  36. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  37. GRB 240718A: Fermi GBM Final Real-time Localization
  38. GRB 240712A: Swift-BAT refined analysis
  39. GRB 240716A: GECAM-B detection of a long burst
  40. SVOM/GRM In-Flight Trigger of GRB 240716A
  41. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  42. GRB 240713A: 2.2m CAHA optical limit
  43. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  44. GRB 240715A: Swift/UVOT observations of the XRT sources.
  45. GRB 240715A: Swift-XRT observations
  46. GRB240713A: Swift/UVOT Upper LImits
  47. EP240708a: X-ray follow-up observations with Swift/XRT
  48. GRB 240715A: GECAM-C detection of a short burst
  49. Konus-Wind detection of GRB 240715A
  50. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  51. GRB 240713A: Swift-XRT observations
  52. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  53. GRB 240712A: Swift-XRT refined Analysis
  54. SVOM/GRM In-Flight Trigger of GRB 240715A
  55. GRB 240713A: LAST optical upper limit
  56. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  57. GRB 240715A: Swift ToO observations
  58. Fermi GRB 240715A: Global MASTER-Net observations report
  59. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  60. GRB 240715A: Fermi GBM Observation
  61. GRB 240712A ATCA radio observations
  62. GRB240715A: GRANDMA Optical Upper Limits
  63. IPN triangulation of GRB 240715A (short)
  64. GW s240422ed: Swift UVOT follow-up
  65. GRB 240712A: Swift/UVOT Upper Limits
  66. EP-WXT flaring star and the optical flaring activity during its decay phase
  67. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  68. The EP-WXT source triggered on July 14th is likely a flaring star
  69. GRB 240715A: Fermi GBM Final Real-time Localization
  70. GRB 240713A: Tiled Swift observations
  71. GRB 240713A: J-band upper limit from WINTER
  72. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  73. GRB 240713A: JinShan optical upper limits
  74. GRB 240713A: OHP/T120 optical upper limit
  75. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  76. GRB240713A: X-ray follow-up observation with EP-FXT
  77. GRB 240713B: AstroSat CZTI detection of a long burst
  78. GRB240713A: Optical upper limit with Kinder observations
  79. Fermi Sub-threshold Observation of GRB240713A
  80. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  81. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  82. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  83. EP240708a: GSP optical upper limit
  84. GRB 240712A: Swift detection of a burst
  85. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  86. GRB 240711A: Fermi GBM Final Real-time Localization
  87. Fermi trigger No 742405878: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  89. Fermi trigger No 742317942: Global MASTER-Net observations report
  90. EP240708a: KAIT optical upper limit
  91. Fermi GRB 240710A: Global MASTER-Net observations report
  92. GRB 240710A: Fermi GBM Final Real-time Localization
  93. EP240708a: NOT optical observations
  94. EP240708a: SVOM/C-GFT optical upper limit
  95. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  96. EP240708a: Optical upper limits with Kinder observations
  97. EP240708a: EP-WXT detection of a fast X-ray transient
  98. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  99. EP240703b: GSP optical upper limit
  100. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB

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