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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"

12316 results found.

  1. EP260707a: TRT optical upper limit
  2. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  3. GRB 260706A: LCO optical upper limit
  4. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 260705A: LCO optical upper limits
  6. GRB 260704A: NOT optical upper limits
  7. EP260703a: EP-FXT follow-up observation
  8. Fermi trigger No 804738310: Global MASTER-Net observations report
  9. Fermi GRB 260703A: Global MASTER-Net observations report
  10. GRB 260614B: ATCA Radio Upper Limits
  11. Fermi trigger No 804552016: Global MASTER-Net observations report
  12. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  13. EP260628a: EP-FXT follow-up observation
  14. Fermi GRB 260628A: Global MASTER-Net observations report
  15. EP260626a: further Liverpool Telescope optical upper limits
  16. EP260626a: COLIBRÍ optical upper limit
  17. EP260626a: Liverpool Telescope upper limits
  18. Konus-Wind detection of GRB 260618B
  19. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  21. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  22. GRB 260619A: Kilonova-Catcher optical upper limit
  23. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  24. Konus-Wind detection of GRB 260616B/EP260616a
  25. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  26. EP260605a: COLIBRÍ optical upper limits
  27. EP260610b: Liverpool Telescope optical upper limits
  28. IceCube-260610A: EP-FXT follow-up observation
  29. EP260610b: GTC likely spectroscopic redshift z = 1.10
  30. GRB 260610B / AT2026owq: Early ATLAS observations
  31. EP260610a: SVOM/VT optical upper limits
  32. Konus-Wind detection of GRB 260601A
  33. EP260610a: COLIBRÍ optical upper limits
  34. GRB 260604C: SVOM/C-GFT upper limit
  35. GRB 260604C: 6 GHz VLA observations
  36. EP260603a: COLIBRÍ optical upper limit
  37. GRB 260604C: LCO optical upper limit
  38. EP260602d: EP-FXT follow-up observation
  39. EP260602c: EP-FXT follow-up observation
  40. GRB 260527A/EP260527a: 6 GHz VLA observations
  41. EP260602d: J-band upper limit with WINTER
  42. EP260602b: J-band upper limit with WINTER
  43. Fermi GRB 260604C: Global MASTER-Net observations report
  44. Fermi GRB 260604C: Global MASTER-Net observations report
  45. SVOM GRB260604.85: Global MASTER-Net observations report
  46. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  47. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  48. EP260603a: Global MASTER-Net observations report
  49. EP260602d: Optical Upper limits with kinder observations
  50. EP260602b: Liverpool Telescope observations
  51. EP260602a: Liverpool Telescope optical upper limits
  52. GRB 260601B / EP260601a: Mondy optical upper limit
  53. GRB 260603A: Kilonova-Catcher optical upper limit
  54. Fermi trigger No 802141998: Global MASTER-Net observations report
  55. SVOM GRB260603.23: Global MASTER-Net observations report
  56. Fermi GRB 260602B: Global MASTER-Net observations report
  57. Fermi GRB 260602B: Global MASTER-Net observations report
  58. GRB 260601B/EP260601a: J-band upper limit with WINTER
  59. EP260602a: Optical upper limits with Kinder observations
  60. Fermi GRB 260601A: Global MASTER-Net observations report
  61. Fermi trigger No 801900520: Global MASTER-Net observations report
  62. GRB 260531A: MAXI/GSC detection
  63. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  64. Fermi GRB 260529A: Global MASTER-Net observations report
  65. EP260526a: SVOM/VT optical upper limits
  66. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  67. Fermi trigger No 801580882: Global MASTER-Net observations report
  68. EP260526a: LCO optical upper limits
  69. EP260526.405: COLIBRÍ optical upper limits
  70. Fermi GRB 260526A: Global MASTER-Net observations report
  71. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  72. EP-WXT 01709266106: NOT optical upper limits
  73. Fermi GRB 260525A: Global MASTER-Net observations report
  74. Fermi GRB 260523A: Global MASTER-Net observations report
  75. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  76. GRB 260522A: GOTO optical upper limit
  77. Fermi trigger No 801135305: Global MASTER-Net observations report
  78. Fermi GRB 260522A: Global MASTER-Net observations report
  79. GRB 260511A: iTelescope T-75 optical detection
  80. Konus-Wind detection of GRB 260519C
  81. Konus-Wind detection of GRB 260518A
  82. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  83. GRB 260509A: CrAO ZTSh optical upper limit
  84. GRB 260516D: GROWTH-India Telescope optical detection
  85. Fermi GRB 260516C: Global MASTER-Net observations report
  86. SVOM GRB260516D: Global MASTER-Net observations report
  87. Fermi GRB 260516B: Global MASTER-Net observations report
  88. EP260514a: COLIBRÍ optical upper limits
  89. SVOM GRB 260515A: Global MASTER-Net observations report
  90. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  91. EP260514a: GROWTH-India Telescope optical upper limit
  92. GRB 260511B: GMG Optical Upper Limit
  93. EP260514a: Global MASTER-Net observations report
  94. EP260512a: LCO optical upper limits
  95. Fermi GRB 260514A: Global MASTER-Net observations report
  96. EP260512a: EP-FXT follow-up observation
  97. EP260512a: Global MASTER-Net observations report
  98. Fermi GRB 260513A: Global MASTER-Net observations report
  99. Fermi GRB 260512A: Global MASTER-Net observations report
  100. Konus-Wind detection of GRB 260511B

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