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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"

6094 results found.

  1. GRB 250215A: Swift-XRT refined Analysis
  2. EP250207B: Chandra localization of the X-ray counterpart
  3. GRB 250207A: Fermi GBM Observation
  4. GRB 250206A: Fermi GBM Observation
  5. GRB 250210A: SVOM/GRM observation of a long burst
  6. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  7. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  8. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  9. GRB 250207A: 1.3m DFOT Optical observations
  10. GRB 250206A: Swift-XRT observations
  11. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  12. GRB 250205A: 1.3m DFOT optical upper limit
  13. GRB 250206A: Fermi-LAT detection
  14. GRB 250207B: Swift-XRT observations
  15. GRB 250207A: Swift-XRT refined Analysis
  16. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  17. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  18. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  19. GRB 250205A: Fermi GBM Observation
  20. GRB 250204B: SVOM/GRM observation of a likely short burst
  21. GRB 250205A: Swift/XRT detection
  22. GRB 250205A: OHP/T193 optical counterpart candidate
  23. GRB 250204B: AstroSat CZTI detection of a short burst
  24. GRB 250129A: LCO late afterglow detection
  25. GRB 250202B: Fermi GBM Detection
  26. GRB 240129A: further SAO RAS optical observations
  27. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  28. Konus-Wind detection of GRB 250129A
  29. GRB 250129A: 1.3m DFOT Optical observations
  30. GRB 250129A: Skynet Continued Optical Observations
  31. GRB 250129A: SAO RAS optical observations
  32. GRB 250129A: optical photometry from Konkoly
  33. GRB 250129A: iTelescope optical observation
  34. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  35. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  36. Ep250125A: 1.3m DFOT optical upper limit
  37. GRB 250129A: Swift-XRT refined Analysis
  38. GRB 250128B: NOT optical upper limit
  39. GRB 250129A: NOT optical observations and redshift confirmation
  40. GRB 250128B: Swift-XRT refined Analysis
  41. GRB 250128B: Fermi GBM Observation
  42. GRB 250127A: Swift-XRT observations
  43. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  44. GRB 250127A: EP-FXT afterglow detection
  45. GRB 250117A: Fermi GBM Observation
  46. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  47. GRB 250118A: Fermi GBM Observation
  48. EP250125a: Optical upper limit with Kinder observations
  49. GRB 250119C: Fermi GBM Observation
  50. GRB 250121A: Fermi GBM Observation
  51. GRB 250121A: Fermi-LAT detection
  52. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  53. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  54. GRB 250119B: Fermi GBM Observation
  55. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  56. GRB 250116A: Fermi-LAT detection
  57. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  58. GRB 250114B: Swift-XRT afterglow detection
  59. GRB 250114B: Swift-XRT observations
  60. GRB 250114A: Swift-XRT refined Analysis
  61. GRB 250114B : GIT optical upper limit
  62. EP250111a: SAO RAS optical upper limit
  63. EP250108a / AT 2025kg: SAO RAS optical observations
  64. GRB 250106A: Swift-XRT afterglow detection
  65. GRB 250101B: Fermi GBM Observation
  66. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  67. GRB 250108A: Swift/XRT afterglow fading
  68. EP-WXT trigger EP250108a:Xinglong optical follow-up observations
  69. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  70. EP250108a: EP-FXT follow-up observation
  71. GRB 250109A: Fermi GBM Observation
  72. GRB 250108B: Swift-XRT refined Analysis
  73. GRB 250108A: Swift-XRT afterglow detection
  74. GRB 250103A: Swift-XRT afterglow detection
  75. GRB 250107A: Fermi GBM Observation
  76. GRB 241228B: Fermi-LAT detection
  77. EPWXT01709129925: Xinglong optical observations
  78. GRB 250106A: Swift-XRT observations
  79. GRB 250103B: Swift-XRT refined Analysis
  80. GRB 250103A: Swift-XRT observations
  81. GRB 250101A: 1.3m DFOT optical afterglow detection
  82. GRB 241229A: 1.3m DFOT upper limit
  83. GRB 241228B: 1.3m DFOT Optical observations
  84. GRB 241228A: 1.3m DFOT upper limit
  85. GRB 250103A: Fermi GBM Observation
  86. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  87. GRB 250101A: further SAO RAS optical observations
  88. GRB 250101A: Swift-XRT refined Analysis
  89. GRB 250101A: SAO RAS optical observations
  90. GRB 241229A: EP-FXT X-ray afterglow confirmation
  91. GRB 241229B: SAO RAS optical upper limit
  92. GRB 241228B: SAO RAS optical observations
  93. GRB 241229A: SAO RAS optical observations
  94. GRB 241229A: Swift-XRT observations
  95. GRB 241229A: EP-FXT afterglow candidates
  96. EP240702a: 7DT Optical upper limits
  97. GRB 241228B: Fermi GBM Observation
  98. GRB 241228B: Swift-XRT afterglow detection
  99. GRB 241229B: Fermi GBM Observation
  100. GRB 241229B: Swift-XRT refined Analysis

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