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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"

24705 results found.

  1. GRB 241030B: Enhanced Swift-XRT position
  2. GRB241030B: GRANDMA/TAROT Upper Limit
  3. GRB 241030A: Swift-XRT refined Analysis
  4. GRB 241030B: SAO RAS optical observations
  5. GRB 241030B: AKO Optical Afterglow Detection
  6. GRB 241030B: Nanshan/HMT optical afterglow detection
  7. GRB 241030B: Swift detection of a burst
  8. GRB 240912A: radio detection with the VLA
  9. GRB 241030A: AKO Optical Afterglow Detection
  10. GRB 241030A: Swift/UVOT Detection
  11. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  12. GRB 241026A: Swift-BAT refined analysis
  13. GRB 241030A: SVOM/C-GFT optical observations
  14. GRB 241026A: LBT optical observations
  15. EP241021a: Optical rebrightening observations with Mephisto
  16. GRB 241030A: Multiband optical detection with Mephisto
  17. GRB 241030A: SVOM/VT optical afterglow observations
  18. GRB 241030A : MITSuME Akeno optical afterglow detection
  19. GRB 241030A: Enhanced Swift-XRT position
  20. GRB 241029A: GROWTH-India Telescope optical follow up
  21. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  22. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  23. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  24. GRB 241029A: SAO RAS optical observations
  25. GRB 241026A: SAO RAS optical observations
  26. EP241021a: SAO RAS observations of rebrightening
  27. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  28. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  29. GRB 241026A: Swift/UVOT Upper Limits
  30. GRB 241029A: Swift-XRT observations
  31. GRB 241029A: Fermi GBM Observation
  32. GRB 241029A: AKO Optical Afterglow Detection
  33. EP241021a: continued SOAR observations confirm optical rebrightening
  34. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  35. GRB 241029A: Mephisto observations
  36. EP 241026b: LBT possible optical counterpart (brightening source)
  37. GRB 241029A: TRT optical afterglow candidate detection
  38. GRB 241026A: TNOT optical counterpart detection
  39. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  40. GRB 241025A: further SAO RAS optical observations
  41. GRB 241026A: BTA and Zeiss-1000 optical observations
  42. GRB 241026A: SVOM/GRM observation
  43. EP241026B: GROWTH-India Telescope optical upper limit
  44. GRB 241025A: Swift/UVOT Detection
  45. GRB 241026A: GROWTH-India Telescope optical observations
  46. GRB 241026A Fermi GBM Analysis
  47. GRB 241026A: J-band observations with WINTER
  48. GRB 241025A: SAO RAS optical observations
  49. GRB 241026A: Las Cumbres optical detection
  50. GRB 241025A: Mondy optical observations
  51. EP241021a: SOAR observations of the optical counterpart
  52. EP241021a: further SAO RAS optical observations
  53. GRB 241026A: Swift-XRT refined Analysis
  54. EP 241026b: LBT optical observations
  55. GRB 241026A: Enhanced Swift-XRT position
  56. EP241026b: EP detection of a fast X-ray transient
  57. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  58. GRB 241026A: SAO RAS observations of possible optical afterglow
  59. GRB 241026A: Swift detection of a burst
  60. GRB241025A: 1.3m DFOT optical afterglow detection
  61. EP241021a: optical follow-up observations with Xinglong Observatory
  62. GRB 241025A: GROWTH-India Telescope optical observations
  63. GRB 241025A: COLIBRÍ Detection of the Afterglow
  64. GRB 241025A: Swift-XRT refined Analysis
  65. GRB 241025C: Fermi GBM Detection
  66. GRB 241025A: Fermi GBM Observation
  67. IPN triangulation of GRB 241022A (short/hard)
  68. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  69. EP 241021a: Swift-XRT observations
  70. GRB 241025A : SVOM/VT optical afterglow observations
  71. EP241021a: Liverpool Telescope optical follow-up observations
  72. GRB 241025A: Enhanced Swift-XRT position
  73. GRB 241025A: DDOTI Afterglow detection
  74. GRB 241025A: TRT optical afterglow observation
  75. GRB 241025A: Swift detection of a burst with an optical counterpart
  76. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  77. GRB 241001A: ATCA radio observations
  78. GRB 241010A: VIRT Optical Upper Limit
  79. EP241021a: SAO RAS optical observations
  80. EP241021a: KAIT optical observations
  81. EP241021a: 1.3m DFOT Optical observations
  82. EP241021a: GSP detects optical candidate counterpart
  83. EP241021a: Optical upper limits with Kinder observations
  84. EP241021a: TRT optical observations
  85. GRB 241018A: SVOM/C-GFT optical observations
  86. EP241021a: NOT likely optical counterpart
  87. EP EP241021a: Global MASTER-Net observations report
  88. GRB241017A: 1.3m DFOT optical upper limit
  89. GRB 241018A: 1.3m DFOT Optical upper limit
  90. EP241021a: GOTO optical upper limits
  91. EP241021a: EP detection of a fast X-ray transient
  92. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  93. GRB 241018A/sb24101802: Mephisto optical upper limit
  94. GRB 241017A/sb24101702: Mephisto optical upper limit
  95. GRB 241018A: Mondy optical upper limit
  96. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  97. GRB 241018A: GROWTH-India telescope optical upper limit
  98. GRB241018A: XingLong Optical Upper Limit
  99. GRB 241018A: Swift-XRT observations
  100. GRB 241018A: REM optical/NIR upper limits

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