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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"

18635 results found.

  1. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  2. GRB 241030A: Rapid release of TESS data.
  3. Swift GRB 241101A: Global MASTER-Net observations report
  4. GRB 241101A: FRAM-ORM optical limit
  5. GRB 241101A: Swift-BAT refined analysis
  6. GRB 241030B: Swift-XRT refined Analysis
  7. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  8. GRB 241101A: Swift detection of a burst
  9. GRB 241030B: Montarrenti Observatory optical upper limit
  10. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  11. GRB 241030A: Fermi GBM Observation
  12. GRB 241030B: LCOGT Optical Upper Limits
  13. GRB 241030B: Swift-BAT refined analysis
  14. GRB 241030A: Swift-BAT refined analysis
  15. GRB 241030B: Swift/UVOT Detection
  16. GRB 241029A: LCO optical detection
  17. Swift GRB241030.77: Global MASTER-Net observations report
  18. GRB 241030B: SVOM/GRM observation
  19. GRB 241030B : MITSuME Akeno optical upper limits
  20. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  21. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  22. GRB241030B: Fermi GBM Observation
  23. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  24. GRB 241030B: Enhanced Swift-XRT position
  25. GRB 241030B: optical observations from the INAF Asiago Observatory
  26. EP241021a: Swift-UVOT detection
  27. GRB241030B: GRANDMA/TAROT Upper Limit
  28. GRB 241030A: Swift-XRT refined Analysis
  29. GRB 241030B: AKO Optical Afterglow Detection
  30. GRB 241030B: Nanshan/HMT optical afterglow detection
  31. GRB 241030B: SVOM/ECLAIRs detection of a burst
  32. GRB 241030B: Prompt enhanced Swift-XRT position
  33. Konus-Wind detection of GRB 241030A
  34. GRB 241030B: Swift detection of a burst
  35. GRB 241030A: Fermi-LAT detection
  36. GRB 241030A: AKO Optical Afterglow Detection
  37. Swift GRB 241030A: Global MASTER-Net observations report
  38. GRB 241030A: Swift/UVOT Detection
  39. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  40. GRB 241030A: SVOM/GRM observation
  41. GRB 241026A: Swift-BAT refined analysis
  42. GRB 241030A: SVOM/C-GFT optical observations
  43. GRB 241030A: Multiband optical detection with Mephisto
  44. GRB 241030A: SVOM/VT optical afterglow observations
  45. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  46. GRB 241030A : MITSuME Akeno optical afterglow detection
  47. GRB 241030A: Enhanced Swift-XRT position
  48. GRB 241030A: TRT optical observations
  49. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  50. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  51. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  52. GRB 241026A: Swift/UVOT Upper Limits
  53. GRB 241029A: Swift-XRT observations
  54. GRB 241029A: Swift ToO observations
  55. GRB 241026A: the 100th GRB detected by GRBAlpha
  56. Konus-Wind detection of GRB 241025A
  57. GRB 241026A: GECAM detection
  58. GRB 241026A: SVOM/GRM observation
  59. GRB 241025A: Swift/UVOT Detection
  60. GRB 241026A: GROWTH-India Telescope optical observations
  61. GRB 241026A Fermi GBM Analysis
  62. GRB 241026A: J-band observations with WINTER
  63. GRB 241025A: SAO RAS optical observations
  64. GRB 241026A: Las Cumbres optical detection
  65. GRB 241025A: Mondy optical observations
  66. GRB 241026A: Swift-XRT refined Analysis
  67. GRB 241026A: Enhanced Swift-XRT position
  68. GRB 241026A: KAIT optical observations
  69. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  70. GRB 241026A: SAO RAS observations of possible optical afterglow
  71. GRB 241026A: Prompt enhanced Swift-XRT position
  72. GRB 241026A: Swift detection of a burst
  73. Swift GRB241026.95: Global MASTER-Net observations report
  74. GRB241025A: 1.3m DFOT optical afterglow detection
  75. GRB 241025A: GROWTH-India Telescope optical observations
  76. GRB 241025A: COLIBRÍ Detection of the Afterglow
  77. GRB 241025A: Swift-XRT refined Analysis
  78. GRB 241025A: Fermi GBM Observation
  79. IPN triangulation of GRB 241022A (short/hard)
  80. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  81. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  82. EP 241021a: Swift-XRT observations
  83. Swift GRB 241025A: Global MASTER-Net observations report
  84. EP241025a (GRB 241025A): EP observations update
  85. EP 241021A: Swift ToO observations
  86. GRB 241025A: Enhanced Swift-XRT position
  87. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  88. GRB 241025A: DDOTI Afterglow detection
  89. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  90. GRB 241025A: SVOM/GRM observation
  91. GRB 241025A: TRT optical afterglow observation
  92. GRB 241025A: Swift detection of a burst with an optical counterpart
  93. GRB 241018A: EP-FXT afterglow detection
  94. GRB 241018A: Mondy optical upper limit
  95. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  96. GRB 241018A: GROWTH-India telescope optical upper limit
  97. GRB 241018A: Swift-XRT observations
  98. GRB 241018A: NOT optical observations
  99. GRB 241018A: Swift ToO observations
  100. GRB 241006A: VIRT Optical Upper Limit

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