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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"

26328 results found.

  1. GRB 241030B: Montarrenti Observatory optical upper limit
  2. EP241026b: Liverpool Telescope optical follow-up
  3. GRB 241030A: SAO RAS optical observations
  4. GRB 241030A: Fermi GBM Observation
  5. EP241021a: AMI-LA radio detection
  6. GRB 241030B : GIT optical upper limits
  7. GRB 241030B: LCOGT Optical Upper Limits
  8. GRB 241030B: Swift-BAT refined analysis
  9. GRB 241030A: Swift-BAT refined analysis
  10. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  11. GRB 241030B: Swift/UVOT Detection
  12. GRB 241029A: LCO optical detection
  13. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  14. GRB 241030B : MITSuME Akeno optical upper limits
  15. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  16. GRB 241030B: SVOM/VT optical afterglow observations
  17. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  18. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  19. GRB241030B: Fermi GBM Observation
  20. GRB 241030B: BTA observations
  21. GRB 241029A: SVOM/VT optical afterglow observations
  22. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  23. GRB 241030B: Enhanced Swift-XRT position
  24. GRB241030B: GRANDMA/TAROT Upper Limit
  25. GRB 241030A: Swift-XRT refined Analysis
  26. GRB 241030B: SAO RAS optical observations
  27. GRB 241030B: AKO Optical Afterglow Detection
  28. GRB 241030B: Nanshan/HMT optical afterglow detection
  29. GRB 241030B: Swift detection of a burst
  30. GRB 240912A: radio detection with the VLA
  31. GRB 241030A: AKO Optical Afterglow Detection
  32. GRB 241030A: Swift/UVOT Detection
  33. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  34. GRB 241026A: Swift-BAT refined analysis
  35. GRB 241030A: SVOM/C-GFT optical observations
  36. GRB 241026A: LBT optical observations
  37. EP241021a: Optical rebrightening observations with Mephisto
  38. GRB 241030A: Multiband optical detection with Mephisto
  39. GRB 241030A: SVOM/VT optical afterglow observations
  40. GRB 241030A : MITSuME Akeno optical afterglow detection
  41. GRB 241030A: Enhanced Swift-XRT position
  42. GRB 241029A: GROWTH-India Telescope optical follow up
  43. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  44. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  45. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  46. GRB 241029A: SAO RAS optical observations
  47. GRB 241026A: SAO RAS optical observations
  48. EP241021a: SAO RAS observations of rebrightening
  49. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  50. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  51. GRB 241026A: Swift/UVOT Upper Limits
  52. GRB 241029A: Swift-XRT observations
  53. GRB 241029A: Fermi GBM Observation
  54. GRB 241029A: AKO Optical Afterglow Detection
  55. EP241021a: continued SOAR observations confirm optical rebrightening
  56. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  57. GRB 241029A: Mephisto observations
  58. EP 241026b: LBT possible optical counterpart (brightening source)
  59. GRB 241029A: TRT optical afterglow candidate detection
  60. GRB 241026A: TNOT optical counterpart detection
  61. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  62. GRB 241025A: further SAO RAS optical observations
  63. GRB 241026A: BTA and Zeiss-1000 optical observations
  64. GRB 241026A: SVOM/GRM observation
  65. EP241026B: GROWTH-India Telescope optical upper limit
  66. GRB 241025A: Swift/UVOT Detection
  67. GRB 241026A: GROWTH-India Telescope optical observations
  68. GRB 241026A Fermi GBM Analysis
  69. GRB 241026A: J-band observations with WINTER
  70. GRB 241025A: SAO RAS optical observations
  71. GRB 241026A: Las Cumbres optical detection
  72. GRB 241025A: Mondy optical observations
  73. EP241021a: SOAR observations of the optical counterpart
  74. EP241021a: further SAO RAS optical observations
  75. GRB 241026A: Swift-XRT refined Analysis
  76. EP 241026b: LBT optical observations
  77. GRB 241026A: Enhanced Swift-XRT position
  78. EP241026b: EP detection of a fast X-ray transient
  79. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  80. GRB 241026A: SAO RAS observations of possible optical afterglow
  81. GRB 241026A: Swift detection of a burst
  82. GRB241025A: 1.3m DFOT optical afterglow detection
  83. EP241021a: optical follow-up observations with Xinglong Observatory
  84. GRB 241025A: GROWTH-India Telescope optical observations
  85. GRB 241025A: COLIBRÍ Detection of the Afterglow
  86. GRB 241025A: Swift-XRT refined Analysis
  87. GRB 241025C: Fermi GBM Detection
  88. GRB 241025A: Fermi GBM Observation
  89. IPN triangulation of GRB 241022A (short/hard)
  90. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  91. EP 241021a: Swift-XRT observations
  92. GRB 241025A : SVOM/VT optical afterglow observations
  93. EP241021a: Liverpool Telescope optical follow-up observations
  94. GRB 241025A: Enhanced Swift-XRT position
  95. GRB 241025A: DDOTI Afterglow detection
  96. GRB 241025A: TRT optical afterglow observation
  97. GRB 241025A: Swift detection of a burst with an optical counterpart
  98. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  99. GRB 241001A: ATCA radio observations
  100. GRB 241010A: VIRT Optical Upper Limit

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