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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"

6402 results found.

  1. EP241101a: Optical upper limits with Kinder observations
  2. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  3. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  4. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  5. EP241101a: EP-WXT detection of a fast X-ray transient
  6. EP241021a: Upper limit from Konus-Wind observations
  7. GRB 241030A: Optical Observations via Virtual Telescope Project
  8. GRB 241030B: Swift-XRT refined Analysis
  9. GRB 241030A: SAO RAS optical observations
  10. GRB 241030A: Fermi GBM Observation
  11. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  12. GRB241030B: Fermi GBM Observation
  13. GRB 241029A: SVOM/VT optical afterglow observations
  14. EP241021a: Swift-UVOT detection
  15. GRB 241030A: Swift-XRT refined Analysis
  16. GRB 241030B: SAO RAS optical observations
  17. Konus-Wind detection of GRB 241030A
  18. GRB 241030A: Fermi-LAT detection
  19. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  20. GRB 241029A: SAO RAS optical observations
  21. EP241021a: SAO RAS observations of rebrightening
  22. GRB 241029A: Swift-XRT observations
  23. GRB 241029A: Fermi GBM Observation
  24. Konus-Wind detection of GRB 241025A
  25. GRB 241025A: further SAO RAS optical observations
  26. GRB 241026A: BTA and Zeiss-1000 optical observations
  27. GRB 241026A Fermi GBM Analysis
  28. GRB 241025A: SAO RAS optical observations
  29. EP241021a: further SAO RAS optical observations
  30. GRB 241026A: Swift-XRT refined Analysis
  31. GRB241025A: 1.3m DFOT optical afterglow detection
  32. ​GRB 241025A: optical photometry from Konkoly
  33. GRB 241025A: Swift-XRT refined Analysis
  34. GRB 241025C: Fermi GBM Detection
  35. GRB 241025A: Fermi GBM Observation
  36. EP 241021a: Swift-XRT observations
  37. EP241025a (GRB 241025A): EP observations update
  38. EP241021a: No Detection in Fermi-GBM Observation
  39. EP241021a: SAO RAS optical observations
  40. EP241021a: 1.3m DFOT Optical observations
  41. EP241021a: Optical upper limits with Kinder observations
  42. EP241021a: TRT optical observations
  43. EP241021a: NOT likely optical counterpart
  44. GRB241017A: 1.3m DFOT optical upper limit
  45. GRB 241018A: 1.3m DFOT Optical upper limit
  46. GRB241018A: XingLong Optical Upper Limit
  47. GRB 241018A: Swift-XRT observations
  48. GRB 241016B: Fermi GBM Observations
  49. GRB 241017A: Swift-XRT observations
  50. GRB 241001A: EP-FXT afterglow detection
  51. GRB 241013B: Fermi GBM Observation
  52. GRB 241013A: Fermi GBM Observation
  53. GRB 241009A: Swift-XRT afterglow detection
  54. GRB 241010A: JinShan optical observations and potential host galaxy
  55. GRB 241010A: Swift-XRT refined Analysis
  56. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  57. GRB 241008A: Fermi GBM Observation
  58. GRB 241008A: Fermi-LAT detection
  59. GRB 241002B: Swift-XRT afterglow detection
  60. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  61. GRB 241006A: Swift-XRT refined Analysis
  62. GRB 241001A: Swift-XRT afterglow detection
  63. GRB 241002B: Fermi GBM Observation
  64. GRB 241002B: Swift-XRT observations
  65. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  66. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  67. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  68. GRB 241002A: Swift-XRT refined Analysis
  69. GRB 241001A: Swift-XRT observations
  70. GRB 240930B: Fermi GBM Observation
  71. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  72. Konus-Wind detection of GRB 240912A
  73. EP240919a / GRB 240919A: SVOM/VT upper limit
  74. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  75. EP240918b and EP240918c: Optical upper limits with Kinder observations
  76. EP240919a: Optical upper limit with Kinder observations
  77. GRB 240919A / EP240919a: SVOM/GRM observation
  78. GRB 240910A: further Swift observations and confirmation of afterglow
  79. EP240918a: Optical upper limits with Kinder observations
  80. GRB 240916A: NOT optical observation
  81. GRB 240916A: Fermi GBM Observation
  82. GRB 240916A: Swift-XRT afterglow detection
  83. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  84. EP240913a: VLT/HAWK-I near-infrared upper limits
  85. GRB 240913C: Fermi GBM detection
  86. GRB 240914A: Swift-XRT observations
  87. GRB 240910A: SVOM/VT optical observations
  88. EP240913a: NOT optical upper limits
  89. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  90. GRB 240905E: further NOT optical observations
  91. GRB 240911A: Swift-XRT observations
  92. GRB 240912A: Swift-XRT refined Analysis
  93. GRB 240912A: Fermi GBM Observation
  94. GRB 240910A: Fermi GBM Observation
  95. GRB 240910A: NOT optical observations
  96. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  97. GRB 240910A: JinShan optical observations
  98. GRB 240825A: 7DT Optical Upper Limit
  99. GRB 240905E: SVOM/VT optical observations
  100. GRB 240910A: SVOM/GRM observation

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