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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"

19194 results found.

  1. GRB 241115C: Fermi GBM Observation
  2. GRB 241115A: Swift-XRT afterglow detection
  3. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  4. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  5. EP241113a: Swift XRT weak detection
  6. GRB 241115A: Fermi GBM Observation
  7. GRB 241115A: LCOGT Optical Upper Limits
  8. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  9. Swift GRB 241115A: Global MASTER-Net observations report
  10. GRB 241115A: Swift detection of a burst
  11. GRB 241113A: Swift-BAT refined analysis
  12. GRB 241113A: PRIME near-infrared upper limits
  13. GRB 241113A: J-band observations with WINTER
  14. GRB 241113B: Swift-XRT observations
  15. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  16. GRB 241113A: KAIT optical observations
  17. GRB 241113A: Swift-XRT refined Analysis
  18. GRB 241113A: Swift/UVOT Detection
  19. GRB 241113A: REM detection of the optical/NIR afterglow
  20. Konus-Wind detection of GRB 241107A (short/hard)
  21. GRB 241113B: Swift ToO observations
  22. GRB 241113A: LCO optical observations
  23. GRB 241113A: Enhanced Swift-XRT position
  24. GRB241113A: LCOGT (40-cm) optical counterpart detection
  25. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  26. GRB 241113A: Swift detection of a burst with an optical counterpart
  27. Swift GRB241113.33: Global MASTER-Net observations report
  28. GRB 241107A: GROWTH-India telescope optical upper limit
  29. GRB 241112B: Swift-XRT afterglow detection
  30. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  31. GRB 241112B: Swift ToO observations
  32. GRB 241107A: INTEGRAL IBIS localization
  33. IPN triangulation of GRB 241107A (short/hard)
  34. GRB 241025A: VZLUSAT-2 detection
  35. GRB 241108A: Swift-XRT observations
  36. GRB 241108A: Swift ToO observations
  37. GRB 241030A: TESS observations
  38. GRB 241105A: EP-FXT follow-up observations
  39. GRB 241105A: SVOM/GRM observation
  40. GRB 241105a: PRIME near-infrared upper limits
  41. GRB 241105A: Swift/UVOT Detection
  42. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  43. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  44. GRB 241105A: BOOTES-7 optical detection
  45. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  46. GRB 241105A: Swift-XRT afterglow detection
  47. GRB 241104A: Swift-XRT observations
  48. GRB 241105A: Swift ToO observations
  49. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  50. GRB 241104A: Swift ToO observations
  51. GRB 241030A: GRBAlpha detection
  52. EP241103a: GIT optical upper limit
  53. EP241103a: GOTO optical upper limit
  54. EP241103a: Swift XRT detection and improved X-ray position
  55. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  56. GRB 241030A: Rapid release of TESS data.
  57. Swift GRB 241101A: Global MASTER-Net observations report
  58. GRB 241101A: FRAM-ORM optical limit
  59. GRB 241101A: Swift-BAT refined analysis
  60. GRB 241030B: Swift-XRT refined Analysis
  61. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  62. GRB 241101A: Swift detection of a burst
  63. GRB 241030B: Montarrenti Observatory optical upper limit
  64. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  65. GRB 241030A: Fermi GBM Observation
  66. GRB 241030B: LCOGT Optical Upper Limits
  67. GRB 241030B: Swift-BAT refined analysis
  68. GRB 241030A: Swift-BAT refined analysis
  69. GRB 241030B: Swift/UVOT Detection
  70. GRB 241029A: LCO optical detection
  71. Swift GRB241030.77: Global MASTER-Net observations report
  72. GRB 241030B: SVOM/GRM observation
  73. GRB 241030B : MITSuME Akeno optical upper limits
  74. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  75. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  76. GRB241030B: Fermi GBM Observation
  77. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  78. GRB 241030B: Enhanced Swift-XRT position
  79. GRB 241030B: optical observations from the INAF Asiago Observatory
  80. EP241021a: Swift-UVOT detection
  81. GRB241030B: GRANDMA/TAROT Upper Limit
  82. GRB 241030A: Swift-XRT refined Analysis
  83. GRB 241030B: AKO Optical Afterglow Detection
  84. GRB 241030B: Nanshan/HMT optical afterglow detection
  85. GRB 241030B: SVOM/ECLAIRs detection of a burst
  86. GRB 241030B: Prompt enhanced Swift-XRT position
  87. Konus-Wind detection of GRB 241030A
  88. GRB 241030B: Swift detection of a burst
  89. GRB 241030A: Fermi-LAT detection
  90. GRB 241030A: AKO Optical Afterglow Detection
  91. Swift GRB 241030A: Global MASTER-Net observations report
  92. GRB 241030A: Swift/UVOT Detection
  93. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  94. GRB 241030A: SVOM/GRM observation
  95. GRB 241026A: Swift-BAT refined analysis
  96. GRB 241030A: SVOM/C-GFT optical observations
  97. GRB 241030A: Multiband optical detection with Mephisto
  98. GRB 241030A: SVOM/VT optical afterglow observations
  99. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  100. GRB 241030A : MITSuME Akeno optical afterglow detection

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