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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32740 results found.

  1. IPN triangulation of GRB 251220B (short)
  2. GRB 251222A: Swift ToO observations
  3. GRB 251222A: SVOM/VT optical candidate
  4. GRB 251222A: SVOM detection of a long burst
  5. EP251220a: PRIME upper limit
  6. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  7. GRB 251221A: PRIME near-infrared observation
  8. EP251220a: NOT optical observations
  9. EP251220a: FTW optical and NIR observations
  10. GRB 251221A: UAFO and Mondy optical upper limit
  11. GRB 251221A: Swift/UVOT Upper Limits
  12. GRB 251221A: Fermi GBM Observation
  13. EP251220a: EP-FXT follow-up observation
  14. GRB 251220B: SVOM/GRM observation of a short burst
  15. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  16. EP 251220a: GOTO optical counterpart detection
  17. GRB 251221A: COLIBRÍ detection of the optical counterpart
  18. EP 251220a: COLIBRÍ detection of the optical counterpart
  19. EP251220a: Global MASTER-Net observations report
  20. GRB 251219A: SVOM/GRM observation of a short burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  22. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  23. IceCube-251218A: COLIBRÍ optical upper limits
  24. GRB 251214B: VIRT Optical Upper Limit
  25. Fermi GRB 251217A: Global MASTER-Net observations report
  26. GRB 251215A: Swift/UVOT Upper LImits
  27. GRB 251215A: Fermi GBM Observation
  28. Fermi GRB 251216A: Global MASTER-Net observations report
  29. GRB 251202A/EP251202a: Koshka optical upper limit
  30. GRB 251214B: Mondy optical upper limit
  31. GRB 251215A: COLIBRÍ optical upper limit
  32. EP251214b: KAIT optical upper limit
  33. Fermi GRB 251215A: Global MASTER-Net observations report
  34. EP251214a: Optical upper limit with Kinder observations
  35. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  36. GRB 251215A: Glowbug gamma-ray detection
  37. GRB 251214B: UAFO optical upper limit
  38. GRB 251214B: VLT/X-shooter observations
  39. GRB 251213A: GRID-10B observation
  40. GRB 251214B: Swift-BAT refined analysis
  41. GRB 251202A: radio detection with the VLA
  42. EP251214b: Global MASTER-Net observations report
  43. EP251214b : Einstein Probe detection of a fast X-ray transient
  44. EP251214b : Einstein Probe detection of a fast X-ray transient
  45. GRB 251214B: AbAO optical observations
  46. GRB 251214B: LCO detection of the optical counterpart
  47. GRB 251209A: GECAM-B observation of a long burst
  48. GRB 251214D: GECAM-B observation of a long burst
  49. GRB 251214B: Fermi GBM Observation
  50. GRB 251209A: Insight-HXMT/HE detection
  51. GRB 251215A: Swift ToO observations
  52. EP251214b (EP trigger 01709250023): LCO optical limits
  53. GRID detection of GRB 251213A
  54. GRB 251203B: AbAO optical observations
  55. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  56. GRB 251214B: GECAM-B observation of a long burst
  57. GRB 251213A: SVOM/GRM observation
  58. EP251214a: KAIT optical upper limit
  59. GRB 251213A: AstroSat CZTI detection
  60. GRB 251214A: AstroSat CZTI detection
  61. GRB 251214B: Swift/UVOT Detection
  62. GRB 251214B: COLIBRÍ observations of the afterglow
  63. EP251214a: EP-FXT non-detection and upper limit
  64. GRB 251214A: GECAM-B observation of a likely long burst
  65. GRB 251214B: 1.3m DFOT optical detection
  66. EP251214a: Global MASTER-Net observations report
  67. GRB 251214B: Xinglong-2.16m optical observation
  68. GRB 251214B : MASTER optical afterglow detection
  69. GRB 251214B: SVOM/C-GFT optical observations
  70. EP251214a: COLIBRÍ optical upper limit
  71. Swift GRB 251214B: Global MASTER-Net observations report
  72. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  73. Fermi GRB 251214A: Global MASTER-Net observations report
  74. EP251212a: Global MASTER-Net observations report
  75. EP251212a: KAIT optical upper limit
  76. EP251212a / GRB 251212A: AstroSat CZTI detection
  77. EP251212a: EP-FXT follow-up observation
  78. GRB 251211B: AstroSat CZTI detection
  79. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  80. GRB 251209A: NuSTAR detection of prompt emission
  81. EP251212a : COLIBRÍ optical upper limit
  82. EP251212a: Einstein Probe detection of an X-ray transient
  83. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  84. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  85. Fermi GRB 251211B: Global MASTER-Net observations report
  86. IceCube-251210A: DDOTI Optical Upper Limit
  87. GRB 251209A: Fermi GBM observation
  88. GRB 251205A: 1.3m DFOT optical upper limit
  89. GRB 251209A: AstroSat CZTI detection
  90. EP251124a: Mondy optical upper limit
  91. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  92. EP251130a: Mondy and AbAO optical observations
  93. GRB 251208A: AstroSat CZTI detection
  94. Fermi GBM Sub-Threshold Detection of GRB 251205A
  95. GRB 251208A: Glowbug gamma-ray detection
  96. GRB 251208B: COLIBRÍ optical upper limits
  97. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  98. GRB 251208C: GECAM-B observation of a short burst
  99. GRB 251208A: GECAM-B observation of a short burst
  100. Fermi GRB 251209A: Global MASTER-Net observations report

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