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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"

45444 results found.

  1. Konus-Wind detection of GRB 241030A
  2. GRB 241030B: Swift detection of a burst
  3. GRB 241030B: Fermi GBM Final Real-time Localization
  4. GRB 241030A: Fermi-LAT detection
  5. GRB 240912A: radio detection with the VLA
  6. Fermi GRB 241030A: Global MASTER-Net observations report
  7. GRB 241030A: AKO Optical Afterglow Detection
  8. Swift GRB 241030A: Global MASTER-Net observations report
  9. GRB 241030A: Swift/UVOT Detection
  10. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  11. GRB 241030A: SVOM/GRM observation
  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. EP241026b: EP-FXT follow-up observation
  17. GRB 241030A: Multiband optical detection with Mephisto
  18. GRB 241030A: SVOM/VT optical afterglow observations
  19. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  20. GRB 241030A : MITSuME Akeno optical afterglow detection
  21. GRB 241030A: Enhanced Swift-XRT position
  22. GRB 241029A: GROWTH-India Telescope optical follow up
  23. GRB 241030A: TRT optical observations
  24. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  25. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  26. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  27. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  28. GRB 241030A: Fermi GBM Final Real-time Localization
  29. GRB 241029A: SAO RAS optical observations
  30. GRB 241026A: SAO RAS optical observations
  31. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  32. EP241021a: SAO RAS observations of rebrightening
  33. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  34. EP241021a: ATCA radio observations
  35. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  36. GRB 241026A: Swift/UVOT Upper Limits
  37. GRB 241029A: Swift-XRT observations
  38. GRB 241029A: Fermi GBM Observation
  39. GRB 241029A: AKO Optical Afterglow Detection
  40. GRB 241029A: GOTO optical afterglow detection
  41. EP241021a: continued SOAR observations confirm optical rebrightening
  42. GRB 241029A: MASTER early optical counterpart detection
  43. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  44. GRB 241029A: Mephisto observations
  45. EP 241026b: LBT possible optical counterpart (brightening source)
  46. GRB 241029A: TRT optical afterglow candidate detection
  47. GRB 241029A: Swift ToO observations
  48. GRB 241029A: SVOM/GRM observation
  49. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  50. Fermi trigger No 751861204: Global MASTER-Net observations report
  51. GRB 241029A: Fermi GBM Final Real-time Localization
  52. GRB 240821A: Keck/LRIS spectroscopic observations
  53. EP241021a: Gemini-South detection of optical rebrightening
  54. GRB 241026A: the 100th GRB detected by GRBAlpha
  55. GRB 241026A: TNOT optical counterpart detection
  56. Konus-Wind detection of GRB 241025A
  57. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  58. GRB 241026A: LBT redshift confirmation
  59. GRB 241026A: GECAM detection
  60. GRB 241025A: further SAO RAS optical observations
  61. GRB 241026A: BTA and Zeiss-1000 optical observations
  62. GRB 241026A: SVOM/GRM observation
  63. EP241026B: GROWTH-India Telescope optical upper limit
  64. GRB 241025A: Swift/UVOT Detection
  65. GRB 241026A: GROWTH-India Telescope optical observations
  66. GRB 241026A Fermi GBM Analysis
  67. GRB 241026A: BTA redshift identification of z = 2.79
  68. GRB 241026A: J-band observations with WINTER
  69. GRB 241025A: SAO RAS optical observations
  70. GRB 241026A: Las Cumbres optical detection
  71. GRB 241025A: Mondy optical observations
  72. EP241021a: SOAR observations of the optical counterpart
  73. EP241021a: further SAO RAS optical observations
  74. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  75. GRB 241026A: Swift-XRT refined Analysis
  76. EP 241026b: LBT optical observations
  77. EP241021a: e-MERLIN radio observation
  78. EP EP241026b: Global MASTER-Net observations report
  79. GRB 241026A: Enhanced Swift-XRT position
  80. GRB 241026A: KAIT optical observations
  81. EP241026b: EP detection of a fast X-ray transient
  82. Fermi trigger No 751616906: Global MASTER-Net observations report
  83. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  84. GRB 241026A: SAO RAS observations of possible optical afterglow
  85. Fermi GRB 241026A: Global MASTER-Net observations report
  86. GRB 241026A: Prompt enhanced Swift-XRT position
  87. GRB 241026A: Swift detection of a burst
  88. Swift GRB241026.95: Global MASTER-Net observations report
  89. GRB 241026A: Fermi GBM Final Real-time Localization
  90. GRB241025A: 1.3m DFOT optical afterglow detection
  91. EP241021a: optical follow-up observations with Xinglong Observatory
  92. ​GRB 241025A: optical photometry from Konkoly
  93. GRB 241025A: GROWTH-India Telescope optical observations
  94. GRB 241025A: COLIBRÍ Detection of the Afterglow
  95. GRB 241025A: Swift-XRT refined Analysis
  96. GRB 241025C: Fermi GBM Detection
  97. GRB 241025A: Fermi GBM Observation
  98. IPN triangulation of GRB 241022A (short/hard)
  99. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  100. GRB 241025C: Fermi GBM Final Localization

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