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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"

20506 results found.

  1. EP260221a: Gemini South z-band upper limit
  2. EP260221a: EP-FXT follow-up observation
  3. EP-WXT01709258519: Xinglong optical upper limit
  4. EP260221a: Xinglong optical upper limit
  5. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  6. EP260221a: GOTO optical upper limit
  7. EP260221a: COLIBRÍ optical upper limit
  8. SVOM alert sb26021801: LCO optical upper limit
  9. EP260221a: Einstein Probe detection of an X-ray transient
  10. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 260219A: GECAM-B observation of a long burst
  12. SVOM alert sb26021801: LAST optical upper limit
  13. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  15. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  16. EP-WXT 01709258455: NOT optical upper limits
  17. EP260214b: Mondy optical observations
  18. EP260214b: 1.3m DFOT optical upper limit
  19. EP260210a: Mondy optical upper limits
  20. GRB 260208A: AbAO and Terskol optical upper limits
  21. GRB 260208A: continued Mondy optical observations
  22. IPN triangulation of GRB 260212A
  23. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  24. EP260214b: Liverpool Telescope optical observations
  25. EP260214b: Optical upper limit with Kinder observations
  26. EP260214a: Optical upper limits with Kinder observations
  27. EP260214b: EP-FXT follow-up observation
  28. EP260214b: DDOTI Optical Detection
  29. EP260214b: GROWTH-India Telescope optical upper limit
  30. EP260214a: VLT near-infrared observation
  31. EP260214a: NOT optical upper limits
  32. EP260214a: COLIBRÍ optical upper limits
  33. EP260214b: OHP/T120 optical observations
  34. EP260214a: refined analysis of the EP-FXT observation
  35. EP260214b: LCO optical counterpart detection
  36. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  37. EP260214b: COLIBRÍ optical observations
  38. EP260214b: NOT optical counterpart detection
  39. EP260214b: Einstein Probe detection of a fast X-ray transient
  40. EP260214a: Einstein Probe detection of an X-ray transient
  41. EP260213a: Liverpool Telescope optical upper limits
  42. EP260213a: COLIBRÍ optical upper limits
  43. EP260213a: Optical upper limits with Kinder observations
  44. EP260213a: Mondy R-band optical upper limit
  45. EP260213a: NUTTelA-TAO Early Optical Limits
  46. EP260213a: SVOM/C-GFT upper limit
  47. EP260213a: refined analysis of the EP-FXT observation
  48. EP260213a: Einstein Probe detection of a fast X-ray transient
  49. EP/WXT 01709258378: NOT optical upper limits
  50. GRB 260212A: SVOM/GRM observation of a long burst
  51. GRB 260211A - SVOM/ECLAIRs refined analysis
  52. GRB 260204A: SVOM/ECLAIRs refined analysis
  53. GRB 260211A: LAST optical upper limit
  54. GRB 260210A: SVOM/GRM observation
  55. GRB 260128B: SVOM/ECLAIRs refined analysis
  56. GRID detection of GRB 260207B
  57. GRB 260211A: LCO optical upper limits
  58. GRB260131A/B: 3.6m DOT Optical Observations
  59. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. GRB 260211A: SVOM detection of a burst
  61. EP260209a: COLIBRÍ optical upper limit
  62. EP260209a: LCO optical upper limits
  63. EP260210a: refined analysis of the EP-FXT observation
  64. GRB 260208A: LCO detection of the optical counterpart
  65. EP260209a: Einstein Probe detection of a fast X-ray transient
  66. EP260210a: Optical upper limits with Kinder observations
  67. GRB 260208C: AstroSat CZTI detection
  68. EP260210a: COLIBRÍ optical upper limit
  69. EP260210a: SVOM/C-GFT upper limit
  70. EP260210a: Einstein Probe detection of an X-ray transient
  71. GRB 260208C: SVOM/GRM observation
  72. GRB 260204A: Swift-XRT afterglow detection
  73. GRB 260208B: AstroSat CZTI detection of a bright long burst
  74. GRB260208A: Liverpool Telescope optical follow-up observations
  75. GRB 260131A/B: continued Mondy optical observations
  76. GRB 260204A: Swift/UVOT Upper Limits
  77. GRB 260208B: COLIBRÍ optical observations
  78. GRB 260208A: Mondy optical observations
  79. GRB 260208A: 1.3m DFOT optical detection
  80. GRB 260208A: COLIBRÍ optical observations
  81. GRB 260208A: NOT spectroscopic redshift z = 2.36
  82. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  83. GRB 260208A: SVOM/VT optical observation
  84. Fermi GRB 260208D: Global MASTER-Net observations report
  85. GRB 260208B: SVOM/GRM observation of a bright burst
  86. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  87. GRB 260131A/B: Mondy and Terskol optical observations
  88. GRB 260204A: Swift-XRT observations
  89. GRB 260204A: SVOM/VT optical candidate
  90. GRB 260204A: LCO optical upper limits
  91. EP260110a: Late GTC/EMIR near-infrared observations
  92. GRB 260204B: Fermi GBM Final Real-time Localization
  93. Konus-Wind detection of GRB 260121A
  94. GRB 260131A: KAIT optical observations
  95. GRB 251230A: MeerLICHT afterglow detection
  96. GRID detection of GRB 260131A/B
  97. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  98. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  99. GRB 260131A: NOT spectroscopic redshift z = 1.434
  100. EP260131a: Liverpool Telescope optical upper limits

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