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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"

22059 results found.

  1. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  2. GRB 240819A: Swift ToO observations
  3. EP240816b: Liverpool Telescope optical follow-up observations
  4. Integral GRB240816.79: Global MASTER-Net observations report
  5. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  6. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  7. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  8. Fermi trigger No 745501396: Global MASTER-Net observations report
  9. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  10. EP EP240816b: Global MASTER-Net observations report
  11. EP240816b: TRT optical upper limit
  12. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  13. Fermi GRB 240814A: Global MASTER-Net observations report
  14. Fermi GRB 240814C: Global MASTER-Net observations report
  15. Fermi trigger No 745306088: Global MASTER-Net observations report
  16. Fermi GRB 240814B: Global MASTER-Net observations report
  17. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  18. Fermi trigger No 745220784: Global MASTER-Net observations report
  19. Konus-Wind detection of GRB 240810A
  20. GRB 240809A: ATA radio non-detection
  21. GRB 240809A : RAPAS follow-up observations
  22. GRB 240809A: VLA detection
  23. GRB 240809A: ALMA detection
  24. EP240807a: PRIME H-band upper limits
  25. GRB 240811A: Bassano Bresciano Observatory upper limit
  26. GRB 240811A: Swift/UVOT Upper Limits
  27. EP240801a: Assy-Turgen optical observations
  28. Fermi GRB 240810A: Global MASTER-Net observations report
  29. GRB 240811A: Upper limits with Mephisto
  30. Konus-Wind detection of GRB 240809A
  31. Fermi trigger No 745057312: Global MASTER-Net observations report
  32. Swift GRB 240811A: Global MASTER-Net observations report
  33. GRB240809A: Liverpool Telescope optical follow-up observations
  34. GRB 240809A: REM detection of the optical afterglow
  35. GRB 240809A: Bassano Bresciano Observatory optical observations
  36. Fermi-LAT gamma-ray observations of IceCube-240808A
  37. GRB 240809A: KAIT optical observations
  38. GRB 240809A: GIT afterglow observations
  39. GRB 240809A: Swift/UVOT Detection
  40. GRB 240809A: Tentative redshift from NOT
  41. X-ray Transient EP240807a: PRIME near-infrared upper limits
  42. Swift GRB 240809A: Global MASTER-Net observations report
  43. GRB 240809A: JinShan optical observations
  44. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  45. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  46. EP240807a: STEP/T80S optical limits
  47. IceCube Alert 240808.27: Global MASTER-Net observations report
  48. EP EP240807a: Global MASTER-Net observations report
  49. EP EP240806a: Global MASTER-Net observations report
  50. GRB 240805A: ATCA Radio Upper Limits
  51. Fermi trigger No 744761058: Global MASTER-Net observations report
  52. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  53. EP240806A: Liverpool Telescope optical follow-up observations
  54. EP240807a: EP-WXT detection of a fast X-ray transient
  55. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  56. GRB 240805B: GIT optical upper limit
  57. EP240806a: KAIT optical observations
  58. Fermi trigger No 744629911: Global MASTER-Net observations report
  59. EP240804a (GRB 240804B): NOT optical observations
  60. EP240806a: LCOGT optical counterpart detection
  61. Konus-Wind detection of GRB 240802A (EP240802a)
  62. Konus-Wind detection of GRB 240805A
  63. GRB 240805B Bassano Bresciano Observatory upper limit
  64. GRB 240805B: JinShan optical afterglow detection
  65. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  66. EP 240806A: LCO optical observations
  67. EP240806a: GSP optical counterpart detection
  68. EP240806a: EP-WXT detection of a fast X-ray transient
  69. GRB 240805B: Optical detection with 1.6m Mephisto
  70. GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
  71. Fermi trigger No 744544656: Global MASTER-Net observations report
  72. GRB 240805B: Swift/UVOT Upper Limits
  73. GRB 240805A: Swift/UVOT Upper Limits
  74. GRB 240805B: BTA optical afterglow candidate
  75. Swift GRB 240805B: Global MASTER-Net observations report
  76. GRB 240805B: JinShan optical upper limits
  77. Fermi GRB 240805A: Global MASTER-Net observations report
  78. Swift GRB 240805A: Global MASTER-Net observations report
  79. EP240804a: GSP detects optical candidate counterpart
  80. EP240801a: Continued optical observations at ZTSh (CraO)
  81. EP240804a: VLT/X-shooter spectroscopic redshift
  82. EP240804a: LCOGT optical counterpart detection
  83. EP240804a: NOT optical counterpart detection
  84. EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  85. GRB 240805A: Swift detection of a burst
  86. Fermi GRB 240804A: Global MASTER-Net observations report
  87. EP240802a: Montarrenti Observatory optical upper limit
  88. Fermi trigger No 744459130: Global MASTER-Net observations report
  89. EP240801a: Osservatorio Astronomico Nastro Verde upper limit
  90. EP240802A: Bassano Bresciano Observatory upper limit
  91. GRB 240802A: SVOM/GRM observation
  92. EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
  93. Fermi trigger No 744278264: Global MASTER-Net observations report
  94. EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  95. EP240801a: further SAO RAS optical observations
  96. EP240801a: optical observations at CrAO and AbAO
  97. EP240801a: GRANDMA and Kilonova-Catcher optical observations
  98. EP240801a: Leavitt Observatory optical observations
  99. EP240801a: GTC spectroscopy and absorption redshift
  100. EP240801a: SAO RAS optical observations

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