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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"

25008 results found.

  1. GRB 241030B: BTA observations
  2. GRB 241029A: SVOM/VT optical afterglow observations
  3. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  4. GRB 241030B: Enhanced Swift-XRT position
  5. GRB241030B: GRANDMA/TAROT Upper Limit
  6. GRB 241030A: Swift-XRT refined Analysis
  7. GRB 241030B: SAO RAS optical observations
  8. GRB 241030B: AKO Optical Afterglow Detection
  9. GRB 241030B: Nanshan/HMT optical afterglow detection
  10. GRB 241030B: Swift detection of a burst
  11. GRB 240912A: radio detection with the VLA
  12. GRB 241030A: AKO Optical Afterglow Detection
  13. GRB 241030A: Swift/UVOT Detection
  14. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  15. GRB 241026A: Swift-BAT refined analysis
  16. GRB 241030A: SVOM/C-GFT optical observations
  17. GRB 241026A: LBT optical observations
  18. EP241021a: Optical rebrightening observations with Mephisto
  19. GRB 241030A: Multiband optical detection with Mephisto
  20. GRB 241030A: SVOM/VT optical afterglow observations
  21. GRB 241030A : MITSuME Akeno optical afterglow detection
  22. GRB 241030A: Enhanced Swift-XRT position
  23. GRB 241029A: GROWTH-India Telescope optical follow up
  24. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  25. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  26. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  27. GRB 241029A: SAO RAS optical observations
  28. GRB 241026A: SAO RAS optical observations
  29. EP241021a: SAO RAS observations of rebrightening
  30. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  31. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  32. GRB 241026A: Swift/UVOT Upper Limits
  33. GRB 241029A: Swift-XRT observations
  34. GRB 241029A: Fermi GBM Observation
  35. GRB 241029A: AKO Optical Afterglow Detection
  36. EP241021a: continued SOAR observations confirm optical rebrightening
  37. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  38. GRB 241029A: Mephisto observations
  39. EP 241026b: LBT possible optical counterpart (brightening source)
  40. GRB 241029A: TRT optical afterglow candidate detection
  41. GRB 241026A: TNOT optical counterpart detection
  42. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  43. GRB 241025A: further SAO RAS optical observations
  44. GRB 241026A: BTA and Zeiss-1000 optical observations
  45. GRB 241026A: SVOM/GRM observation
  46. EP241026B: GROWTH-India Telescope optical upper limit
  47. GRB 241025A: Swift/UVOT Detection
  48. GRB 241026A: GROWTH-India Telescope optical observations
  49. GRB 241026A Fermi GBM Analysis
  50. GRB 241026A: J-band observations with WINTER
  51. GRB 241025A: SAO RAS optical observations
  52. GRB 241026A: Las Cumbres optical detection
  53. GRB 241025A: Mondy optical observations
  54. EP241021a: SOAR observations of the optical counterpart
  55. EP241021a: further SAO RAS optical observations
  56. GRB 241026A: Swift-XRT refined Analysis
  57. EP 241026b: LBT optical observations
  58. GRB 241026A: Enhanced Swift-XRT position
  59. EP241026b: EP detection of a fast X-ray transient
  60. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  61. GRB 241026A: SAO RAS observations of possible optical afterglow
  62. GRB 241026A: Swift detection of a burst
  63. GRB241025A: 1.3m DFOT optical afterglow detection
  64. EP241021a: optical follow-up observations with Xinglong Observatory
  65. GRB 241025A: GROWTH-India Telescope optical observations
  66. GRB 241025A: COLIBRÍ Detection of the Afterglow
  67. GRB 241025A: Swift-XRT refined Analysis
  68. GRB 241025C: Fermi GBM Detection
  69. GRB 241025A: Fermi GBM Observation
  70. IPN triangulation of GRB 241022A (short/hard)
  71. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  72. EP 241021a: Swift-XRT observations
  73. GRB 241025A : SVOM/VT optical afterglow observations
  74. EP241021a: Liverpool Telescope optical follow-up observations
  75. GRB 241025A: Enhanced Swift-XRT position
  76. GRB 241025A: DDOTI Afterglow detection
  77. GRB 241025A: TRT optical afterglow observation
  78. GRB 241025A: Swift detection of a burst with an optical counterpart
  79. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  80. GRB 241001A: ATCA radio observations
  81. GRB 241010A: VIRT Optical Upper Limit
  82. EP241021a: SAO RAS optical observations
  83. EP241021a: KAIT optical observations
  84. EP241021a: 1.3m DFOT Optical observations
  85. EP241021a: GSP detects optical candidate counterpart
  86. EP241021a: Optical upper limits with Kinder observations
  87. EP241021a: TRT optical observations
  88. GRB 241018A: SVOM/C-GFT optical observations
  89. EP241021a: NOT likely optical counterpart
  90. EP EP241021a: Global MASTER-Net observations report
  91. GRB241017A: 1.3m DFOT optical upper limit
  92. GRB 241018A: 1.3m DFOT Optical upper limit
  93. EP241021a: GOTO optical upper limits
  94. EP241021a: EP detection of a fast X-ray transient
  95. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 241018A/sb24101802: Mephisto optical upper limit
  97. GRB 241017A/sb24101702: Mephisto optical upper limit
  98. GRB 241018A: Mondy optical upper limit
  99. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  100. GRB 241018A: GROWTH-India telescope optical upper limit

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