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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"

32509 results found.

  1. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  2. GRB 241026A: LBT redshift confirmation
  3. GRB 241026A: GECAM detection
  4. GRB 241025A: further SAO RAS optical observations
  5. GRB 241026A: BTA and Zeiss-1000 optical observations
  6. GRB 241026A: SVOM/GRM observation
  7. EP241026B: GROWTH-India Telescope optical upper limit
  8. GRB 241025A: Swift/UVOT Detection
  9. GRB 241026A: GROWTH-India Telescope optical observations
  10. GRB 241026A Fermi GBM Analysis
  11. GRB 241026A: BTA redshift identification of z = 2.79
  12. GRB 241026A: J-band observations with WINTER
  13. GRB 241025A: SAO RAS optical observations
  14. GRB 241026A: Las Cumbres optical detection
  15. GRB 241025A: Mondy optical observations
  16. EP241021a: SOAR observations of the optical counterpart
  17. EP241021a: further SAO RAS optical observations
  18. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  19. EP 241026b: LBT optical observations
  20. EP241021a: e-MERLIN radio observation
  21. EP EP241026b: Global MASTER-Net observations report
  22. GRB 241026A: KAIT optical observations
  23. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  24. GRB 241026A: SAO RAS observations of possible optical afterglow
  25. Fermi GRB 241026A: Global MASTER-Net observations report
  26. GRB241025A: 1.3m DFOT optical afterglow detection
  27. EP241021a: optical follow-up observations with Xinglong Observatory
  28. ​GRB 241025A: optical photometry from Konkoly
  29. GRB 241025A: GROWTH-India Telescope optical observations
  30. GRB 241025A: COLIBRÍ Detection of the Afterglow
  31. GRB 241025C: Fermi GBM Detection
  32. GRB 241025A: Fermi GBM Observation
  33. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  34. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  35. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  36. EP 241021a: Swift-XRT observations
  37. EP241021a: optical follow-up observations with the Liverpool Telescope
  38. Fermi GRB 241025A: Global MASTER-Net observations report
  39. Swift GRB 241025A: Global MASTER-Net observations report
  40. EP241025a (GRB 241025A): EP observations update
  41. GRB 241025A : SVOM/VT optical afterglow observations
  42. EP 241021A: Swift ToO observations
  43. EP241021a: Liverpool Telescope optical follow-up observations
  44. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  45. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  46. GRB 241025A: DDOTI Afterglow detection
  47. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  48. GRB 241025A: SVOM/GRM observation
  49. GRB 241025A: TRT optical afterglow observation
  50. Fermi GRB 241024B: Global MASTER-Net observations report
  51. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  52. GRB 241001A: ATCA radio observations
  53. EP241021a: No Detection in Fermi-GBM Observation
  54. GRB 241010A: VIRT Optical Upper Limit
  55. EP241021a: VLT/FORS2 redshift z = 0.75
  56. EP241021a: SAO RAS optical observations
  57. EP241021a: KAIT optical observations
  58. EP241021a: EP-FXT follow-up observation update
  59. IPN triangulation of GRB 241021A (long)
  60. EP241021a: Optical counterpart observations with the Liverpool Telescope
  61. EP241021a: 1.3m DFOT Optical observations
  62. EP241021a: GSP detects optical candidate counterpart
  63. EP241021a: Optical upper limits with Kinder observations
  64. EP241021a: TRT optical observations
  65. GRB 241018A: SVOM/C-GFT optical observations
  66. EP241021a: NOT likely optical counterpart
  67. EP EP241021a: Global MASTER-Net observations report
  68. GRB241017A: 1.3m DFOT optical upper limit
  69. GRB 241018A: 1.3m DFOT Optical upper limit
  70. GRB 241018A: EP-FXT afterglow detection
  71. EP241021a: GOTO optical upper limits
  72. Konus-Wind detection of GRB 241018A
  73. GRB 241018A: SVOM/GRM observation
  74. GRB 241018A/sb24101802: Mephisto optical upper limit
  75. GRB 241017A/sb24101702: Mephisto optical upper limit
  76. GRB 241018A: Mondy optical upper limit
  77. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  78. GRB 241018A: GROWTH-India telescope optical upper limit
  79. GRB241018A: XingLong Optical Upper Limit
  80. GRB 241018A: REM optical/NIR upper limits
  81. GRB 241018A: NOT optical observations
  82. GRB 241017A: SVOM/VT follow-up and optical upper limit
  83. GRB 241018A: SVOM/VT follow-up and optical candidate
  84. GRB 241018A: LCO/0.4m optical upper limits
  85. GRB 241018A: Swift ToO observations
  86. GRB 241006A: VIRT Optical Upper Limit
  87. GRB 240727A: VIRT Optical Upper Limit
  88. GRB 241018A: X-ray afterglow candidate observed by MXT
  89. GRB 241016B: Fermi GBM Observations
  90. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  91. GRB 241001A: EP-FXT afterglow detection
  92. GRB 241017A: GROWTH-India Telescope optical upper limit
  93. GRB241017A: TOO Observations by SVOM/MXT
  94. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  95. GRB 241017A: J-band upper limit from WINTER
  96. GRB 241016B: SVOM/GRM observation
  97. GRB 241017A: Swift ToO observations
  98. Fermi GRB 241016B: Global MASTER-Net observations report
  99. Fermi GRB 241016A: Global MASTER-Net observations report
  100. GRB 241010A: Swift-BAT refined analysis

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