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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"

22054 results found.

  1. EP240801a: Kinder follow-up observations of the candidate counterpart
  2. EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
  3. EP240801a: KAIT optical counterpart observations
  4. EP240801a: TRT optical counterpart detection
  5. EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  6. Fermi GRB 240801A: Global MASTER-Net observations report
  7. Fermi trigger No 744128417: Global MASTER-Net observations report
  8. Fermi trigger No 744083370: Global MASTER-Net observations report
  9. GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
  10. Fermi GRB 240730B: Global MASTER-Net observations report
  11. Swift GRB 240730A: Global MASTER-Net observations report
  12. GRB 240715A: Swift-XRT afterglow detection
  13. GRB 240730A: Swift/UVOT Upper Limits
  14. GRB 240730A: Swift detection of a burst
  15. Fermi trigger No 743953682: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  17. GRB 240727A: observations of optical counterpart.
  18. GRB 240727B: Swift-XRT observations
  19. Fermi GRB 240727A: Global MASTER-Net observations report
  20. GRB 240727A: Swift/UVOT detection
  21. Fermi trigger No 743868421: Global MASTER-Net observations report
  22. GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
  23. GRB 240727A: JinShan optical upper limits
  24. GRB 240727A Bassano Bresciano Observatory upper limit
  25. Fermi GRB 240726A: Global MASTER-Net observations report
  26. Swift GRB240727.16: Global MASTER-Net observations report
  27. GRB 240727B: Swift ToO observations
  28. GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
  29. GRB240727A: Skynet Optical Afterglow Observations
  30. GRB 240727A: TRT optical afterglow detection
  31. GRB 240727A: KAIT Optical Afterglow Candidate
  32. Fermi-LAT gamma-ray observations of IceCube-240725A
  33. IceCube Alert 240725.22: Global MASTER-Net observations report
  34. Swift GRB240725.11: Global MASTER-Net observations report
  35. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  36. Fermi trigger No 743418632: Global MASTER-Net observations report
  37. Fermi trigger No 743315411: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  39. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  40. Fermi trigger No 743345551: Global MASTER-Net observations report
  41. Fermi-LAT gamma-ray observations of IceCube-240721A
  42. Fermi trigger No 743219692: Global MASTER-Net observations report
  43. IceCube Alert 240721.68: Global MASTER-Net observations report
  44. Fermi GRB 240720A: Global MASTER-Net observations report
  45. Swift GRB240720.02: Global MASTER-Net observations report
  46. Konus-Wind detection of GRB 240718A
  47. Fermi GRB 240718A: Global MASTER-Net observations report
  48. LAT GRB240718.27: Global MASTER-Net observations report
  49. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  50. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  51. GRB 240715A: Swift/UVOT observations of the XRT sources.
  52. GRB 240715A: Swift-XRT observations
  53. GRB240713A: Swift/UVOT Upper LImits
  54. EP240708a: X-ray follow-up observations with Swift/XRT
  55. GRB 240713A: Swift-XRT observations
  56. GRB 240713A: LAST optical upper limit
  57. GRB 240715A: Swift ToO observations
  58. Fermi GRB 240715A: Global MASTER-Net observations report
  59. GRB 240712A ATCA radio observations
  60. GRB240715A: GRANDMA Optical Upper Limits
  61. GRB 240712A: Swift/UVOT Upper Limits
  62. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  63. The EP-WXT source triggered on July 14th is likely a flaring star
  64. GRB 240713A: Tiled Swift observations
  65. GRB 240713A: J-band upper limit from WINTER
  66. GRB 240713A: JinShan optical upper limits
  67. GRB 240713A: OHP/T120 optical upper limit
  68. GRB240713A: Optical upper limit with Kinder observations
  69. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  70. EP240708a: GSP optical upper limit
  71. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  72. Fermi trigger No 742405878: Global MASTER-Net observations report
  73. Fermi trigger No 742317942: Global MASTER-Net observations report
  74. Fermi GRB 240710A: Global MASTER-Net observations report
  75. EP240708a: NOT optical observations
  76. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  77. EP240708a: Optical upper limits with Kinder observations
  78. EP240708a: EP-WXT detection of a fast X-ray transient
  79. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  80. EP240703b: GSP optical upper limit
  81. EP240703b: TRT optical upper limits
  82. EP240703a: TRT further optical observation
  83. EP240702a: TRT optical upper limits
  84. Konus-Wind detection of GRB 240627A
  85. EP240703a and EP240703b: Swift/XRT upper limits
  86. EP240703a: BTA observations
  87. EP240703c: Kinder optical follow-up and Swift XRT observations
  88. EP240703a: Liverpool Telescope optical follow-up observations
  89. EP240703a: Kinder optical follow-up observations
  90. EP240703c: EP-WXT detection of an X-ray transient
  91. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  92. EP240703b: EP-WXT detection of a fast X-ray transient
  93. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  94. EP240703a: EP-WXT detection of a fast X-ray transient
  95. EP240702a: GSP optical upper limit
  96. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  97. Fermi GRB 240702A: Global MASTER-Net observations report
  98. EP240702a: EP-WXT detection of a fast X-ray transient
  99. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  100. Fermi trigger No 741448122: Global MASTER-Net observations report

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