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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"

25905 results found.

  1. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  2. GRB 241030B: Enhanced Swift-XRT position
  3. GRB 241030B: optical observations from the INAF Asiago Observatory
  4. EP241021a: Swift-UVOT detection
  5. GRB241030B: GRANDMA/TAROT Upper Limit
  6. GRB 241030A: Swift-XRT refined Analysis
  7. GRB 241030B: AKO Optical Afterglow Detection
  8. GRB 241030B: Nanshan/HMT optical afterglow detection
  9. GRB 241030B: SVOM/ECLAIRs detection of a burst
  10. GRB 241030B: Prompt enhanced Swift-XRT position
  11. Konus-Wind detection of GRB 241030A
  12. GRB 241030B: Swift detection of a burst
  13. GRB 241030A: Fermi-LAT detection
  14. GRB 241030A: AKO Optical Afterglow Detection
  15. Swift GRB 241030A: Global MASTER-Net observations report
  16. GRB 241030A: Swift/UVOT Detection
  17. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  18. GRB 241030A: SVOM/GRM observation
  19. GRB 241026A: Swift-BAT refined analysis
  20. GRB 241030A: SVOM/C-GFT optical observations
  21. GRB 241026A: LBT optical observations
  22. GRB 241030A: Multiband optical detection with Mephisto
  23. GRB 241030A: SVOM/VT optical afterglow observations
  24. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  25. GRB 241030A : MITSuME Akeno optical afterglow detection
  26. GRB 241030A: Enhanced Swift-XRT position
  27. GRB 241029A: GROWTH-India Telescope optical follow up
  28. GRB 241030A: TRT optical observations
  29. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  30. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  31. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  32. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  33. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  34. GRB 241026A: Swift/UVOT Upper Limits
  35. GRB 241029A: Swift-XRT observations
  36. GRB 241029A: AKO Optical Afterglow Detection
  37. GRB 241029A: GOTO optical afterglow detection
  38. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  39. GRB 241029A: TRT optical afterglow candidate detection
  40. GRB 241029A: Swift ToO observations
  41. GRB 240821A: Keck/LRIS spectroscopic observations
  42. GRB 241026A: the 100th GRB detected by GRBAlpha
  43. GRB 241026A: TNOT optical counterpart detection
  44. Konus-Wind detection of GRB 241025A
  45. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  46. GRB 241026A: GECAM detection
  47. GRB 241026A: SVOM/GRM observation
  48. GRB 241025A: Swift/UVOT Detection
  49. GRB 241026A: GROWTH-India Telescope optical observations
  50. GRB 241026A Fermi GBM Analysis
  51. GRB 241026A: BTA redshift identification of z = 2.79
  52. GRB 241026A: J-band observations with WINTER
  53. GRB 241025A: SAO RAS optical observations
  54. GRB 241026A: Las Cumbres optical detection
  55. GRB 241025A: Mondy optical observations
  56. GRB 241026A: Swift-XRT refined Analysis
  57. GRB 241026A: Enhanced Swift-XRT position
  58. GRB 241026A: KAIT optical observations
  59. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  60. GRB 241026A: SAO RAS observations of possible optical afterglow
  61. GRB 241026A: Prompt enhanced Swift-XRT position
  62. GRB 241026A: Swift detection of a burst
  63. Swift GRB241026.95: Global MASTER-Net observations report
  64. GRB241025A: 1.3m DFOT optical afterglow detection
  65. ​GRB 241025A: optical photometry from Konkoly
  66. GRB 241025A: GROWTH-India Telescope optical observations
  67. GRB 241025A: COLIBRÍ Detection of the Afterglow
  68. GRB 241025A: Swift-XRT refined Analysis
  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. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  73. EP 241021a: Swift-XRT observations
  74. Swift GRB 241025A: Global MASTER-Net observations report
  75. EP241025a (GRB 241025A): EP observations update
  76. GRB 241025A : SVOM/VT optical afterglow observations
  77. EP 241021A: Swift ToO observations
  78. GRB 241025A: Enhanced Swift-XRT position
  79. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  80. GRB 241025A: DDOTI Afterglow detection
  81. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  82. GRB 241025A: SVOM/GRM observation
  83. GRB 241025A: TRT optical afterglow observation
  84. GRB 241025A: Swift detection of a burst with an optical counterpart
  85. GRB 241001A: ATCA radio observations
  86. GRB 241010A: VIRT Optical Upper Limit
  87. EP241021a: VLT/FORS2 redshift z = 0.75
  88. EP241021a: KAIT optical observations
  89. EP241021a: EP-FXT follow-up observation update
  90. GRB241017A: 1.3m DFOT optical upper limit
  91. GRB 241018A: 1.3m DFOT Optical upper limit
  92. GRB 241018A: EP-FXT afterglow detection
  93. GRB 241018A: BOOTES-4/MET optical upper limit
  94. GRB 241018A: Mondy optical upper limit
  95. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  96. GRB 241018A: GROWTH-India telescope optical upper limit
  97. GRB 241018A: Swift-XRT observations
  98. GRB 241018A: REM optical/NIR upper limits
  99. GRB 241018A: NOT optical observations
  100. GRB 241018A: LCO/0.4m optical upper limits

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