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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"

6798 results found.

  1. GRANDMA/OPD observations of GRB250215A
  2. GRB 250215A: Swift/UVOT Upper Limits
  3. GRB 250215A: Fermi GBM Observation
  4. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  5. GRB 250215A: Swift-XRT refined Analysis
  6. EP250207B: Chandra localization of the X-ray counterpart
  7. GRB 250207A: Fermi GBM Observation
  8. GRB 250206A: Fermi GBM Observation
  9. GRB 250210A: SVOM/GRM observation of a long burst
  10. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  12. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  13. GRB 250207A: 1.3m DFOT Optical observations
  14. GRB 250206A: Swift-XRT observations
  15. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  16. GRB 250205A: 1.3m DFOT optical upper limit
  17. GRB 250206A: Fermi-LAT detection
  18. GRB 250207B: Swift-XRT observations
  19. GRB 250207A: Swift-XRT refined Analysis
  20. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  21. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  22. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  23. GRB 250205A: Fermi GBM Observation
  24. GRB 250204B: SVOM/GRM observation of a likely short burst
  25. GRB 250205A: Swift/XRT detection
  26. GRB 250205A: OHP/T193 optical counterpart candidate
  27. GRB 250204B: AstroSat CZTI detection of a short burst
  28. GRB 250129A: LCO late afterglow detection
  29. GRB 250202B: Fermi GBM Detection
  30. GRB 240129A: further SAO RAS optical observations
  31. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  32. Konus-Wind detection of GRB 250129A
  33. GRB 250129A: 1.3m DFOT Optical observations
  34. GRB 250129A: Skynet Continued Optical Observations
  35. GRB 250129A: SAO RAS optical observations
  36. GRB 250129A: optical photometry from Konkoly
  37. GRB 250129A: iTelescope optical observation
  38. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  39. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  40. Ep250125A: 1.3m DFOT optical upper limit
  41. GRB 250129A: Swift-XRT refined Analysis
  42. GRB 250128B: NOT optical upper limit
  43. GRB 250129A: NOT optical observations and redshift confirmation
  44. GRB 250128B: Swift-XRT refined Analysis
  45. GRB 250128B: Fermi GBM Observation
  46. GRB 250127A: Swift-XRT observations
  47. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  48. GRB 250127A: EP-FXT afterglow detection
  49. GRB 250117A: Fermi GBM Observation
  50. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  51. GRB 250118A: Fermi GBM Observation
  52. EP250125a: Optical upper limit with Kinder observations
  53. GRB 250119C: Fermi GBM Observation
  54. GRB 250121A: Fermi GBM Observation
  55. GRB 250121A: Fermi-LAT detection
  56. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  57. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  58. GRB 250119B: Fermi GBM Observation
  59. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  60. GRB 250116A: Fermi-LAT detection
  61. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  62. GRB 250114B: Swift-XRT afterglow detection
  63. GRB 250114B: Swift-XRT observations
  64. GRB 250114A: Swift-XRT refined Analysis
  65. GRB 250114B : GIT optical upper limit
  66. EP250111a: SAO RAS optical upper limit
  67. EP250108a / AT 2025kg: SAO RAS optical observations
  68. GRB 250106A: Swift-XRT afterglow detection
  69. GRB 250101B: Fermi GBM Observation
  70. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  71. GRB 250108A: Swift/XRT afterglow fading
  72. EP-WXT trigger EP250108a:Xinglong optical follow-up observations
  73. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  74. EP250108a: EP-FXT follow-up observation
  75. GRB 250109A: Fermi GBM Observation
  76. GRB 250108B: Swift-XRT refined Analysis
  77. GRB 250108A: Swift-XRT afterglow detection
  78. GRB 250103A: Swift-XRT afterglow detection
  79. GRB 250107A: Fermi GBM Observation
  80. GRB 241228B: Fermi-LAT detection
  81. EPWXT01709129925: Xinglong optical observations
  82. GRB 250106A: Swift-XRT observations
  83. GRB 250103B: Swift-XRT refined Analysis
  84. GRB 250103A: Swift-XRT observations
  85. GRB 250101A: 1.3m DFOT optical afterglow detection
  86. GRB 241229A: 1.3m DFOT upper limit
  87. GRB 241228B: 1.3m DFOT Optical observations
  88. GRB 241228A: 1.3m DFOT upper limit
  89. GRB 250103A: Fermi GBM Observation
  90. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  91. GRB 250101A: further SAO RAS optical observations
  92. GRB 250101A: Swift-XRT refined Analysis
  93. GRB 250101A: SAO RAS optical observations
  94. GRB 241229A: EP-FXT X-ray afterglow confirmation
  95. GRB 241229B: SAO RAS optical upper limit
  96. GRB 241228B: SAO RAS optical observations
  97. GRB 241229A: SAO RAS optical observations
  98. GRB 241229A: Swift-XRT observations
  99. GRB 241229A: EP-FXT afterglow candidates
  100. EP240702a: 7DT Optical upper limits

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