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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"

38262 results found.

  1. GRB 241026A: SAO RAS optical observations
  2. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  3. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  4. GRB 241101A: Swift detection of a burst
  5. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  6. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  7. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  8. GRB 241030B: Montarrenti Observatory optical upper limit
  9. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  10. Fermi trigger No 752083996: Global MASTER-Net observations report
  11. GRB 241030A: SAO RAS optical observations
  12. GRB 241030A: Fermi GBM Observation
  13. GRB 241030B : GIT optical upper limits
  14. GRB 241030B: LCOGT Optical Upper Limits
  15. GRB 241030B: Swift-BAT refined analysis
  16. GRB 241030A: Swift-BAT refined analysis
  17. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  18. GRB 241030B: Swift/UVOT Detection
  19. EP EP241030a: Global MASTER-Net observations report
  20. GRB 241029A: LCO optical detection
  21. Fermi trigger No 752006065: Global MASTER-Net observations report
  22. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  23. Swift GRB241030.77: Global MASTER-Net observations report
  24. GRB 241030B: SVOM/GRM observation
  25. GRB 241030B : MITSuME Akeno optical upper limits
  26. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  27. GRB 241030B: SVOM/VT optical afterglow observations
  28. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  29. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  30. GRB241030B: Fermi GBM Observation
  31. GRB 241030B: BTA observations
  32. GRB 241029A: SVOM/VT optical afterglow observations
  33. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  34. GRB 241030B: Enhanced Swift-XRT position
  35. GRB 241030B: optical observations from the INAF Asiago Observatory
  36. GRB241030B: GRANDMA/TAROT Upper Limit
  37. GRB 241030A: Swift-XRT refined Analysis
  38. GRB 241030B: SAO RAS optical observations
  39. GRB 241030B: AKO Optical Afterglow Detection
  40. GRB 241030B: Nanshan/HMT optical afterglow detection
  41. GRB 241030B: SVOM/ECLAIRs detection of a burst
  42. GRB 241030B: Prompt enhanced Swift-XRT position
  43. Konus-Wind detection of GRB 241030A
  44. GRB 241030B: Swift detection of a burst
  45. GRB 241030B: Fermi GBM Final Real-time Localization
  46. GRB 241030A: Fermi-LAT detection
  47. GRB 240912A: radio detection with the VLA
  48. Fermi GRB 241030A: Global MASTER-Net observations report
  49. GRB 241030A: AKO Optical Afterglow Detection
  50. Swift GRB 241030A: Global MASTER-Net observations report
  51. GRB 241030A: Swift/UVOT Detection
  52. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  53. GRB 241030A: SVOM/GRM observation
  54. GRB 241026A: Swift-BAT refined analysis
  55. GRB 241030A: SVOM/C-GFT optical observations
  56. GRB 241026A: LBT optical observations
  57. EP241021a: Optical rebrightening observations with Mephisto
  58. GRB 241030A: Multiband optical detection with Mephisto
  59. GRB 241030A: SVOM/VT optical afterglow observations
  60. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  61. GRB 241030A : MITSuME Akeno optical afterglow detection
  62. GRB 241030A: Enhanced Swift-XRT position
  63. GRB 241029A: GROWTH-India Telescope optical follow up
  64. GRB 241030A: TRT optical observations
  65. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  66. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  67. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  68. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  69. GRB 241030A: Fermi GBM Final Real-time Localization
  70. GRB 241029A: SAO RAS optical observations
  71. GRB 241026A: SAO RAS optical observations
  72. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  73. EP241021a: SAO RAS observations of rebrightening
  74. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  75. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  76. GRB 241026A: Swift/UVOT Upper Limits
  77. GRB 241029A: Swift-XRT observations
  78. GRB 241029A: Fermi GBM Observation
  79. GRB 241029A: AKO Optical Afterglow Detection
  80. GRB 241029A: GOTO optical afterglow detection
  81. GRB 241029A: MASTER early optical counterpart detection
  82. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  83. GRB 241029A: Mephisto observations
  84. EP 241026b: LBT possible optical counterpart (brightening source)
  85. GRB 241029A: TRT optical afterglow candidate detection
  86. GRB 241029A: Swift ToO observations
  87. GRB 241029A: SVOM/GRM observation
  88. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  89. Fermi trigger No 751861204: Global MASTER-Net observations report
  90. GRB 241029A: Fermi GBM Final Real-time Localization
  91. GRB 240821A: Keck/LRIS spectroscopic observations
  92. GRB 241026A: the 100th GRB detected by GRBAlpha
  93. GRB 241026A: TNOT optical counterpart detection
  94. Konus-Wind detection of GRB 241025A
  95. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  96. GRB 241026A: LBT redshift confirmation
  97. GRB 241026A: GECAM detection
  98. GRB 241025A: further SAO RAS optical observations
  99. GRB 241026A: BTA and Zeiss-1000 optical observations
  100. GRB 241026A: SVOM/GRM observation

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