Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

20968 results found.

  1. GRB 241029A: SVOM/VT optical afterglow observations
  2. GRB 241030B: optical observations from the INAF Asiago Observatory
  3. GRB241030B: GRANDMA/TAROT Upper Limit
  4. GRB 241030B: SAO RAS optical observations
  5. GRB 241030B: Nanshan/HMT optical afterglow detection
  6. GRB 240912A: radio detection with the VLA
  7. Fermi GRB 241030A: Global MASTER-Net observations report
  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/C-GFT optical observations
  12. GRB 241026A: LBT optical observations
  13. EP241021a: Optical rebrightening observations with Mephisto
  14. GRB 241030A: Multiband optical detection with Mephisto
  15. GRB 241030A: SVOM/VT optical afterglow observations
  16. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  17. GRB 241030A: TRT optical observations
  18. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  19. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  20. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  21. GRB 241029A: SAO RAS optical observations
  22. GRB 241026A: SAO RAS optical observations
  23. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  24. EP241021a: SAO RAS observations of rebrightening
  25. EP241021a: ATCA radio observations
  26. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  27. GRB 241026A: Swift/UVOT Upper Limits
  28. GRB 241029A: Swift-XRT observations
  29. GRB 241029A: GOTO optical afterglow detection
  30. EP241021a: continued SOAR observations confirm optical rebrightening
  31. GRB 241029A: MASTER early optical counterpart detection
  32. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  33. GRB 241029A: Mephisto observations
  34. EP 241026b: LBT possible optical counterpart (brightening source)
  35. GRB 241029A: TRT optical afterglow candidate detection
  36. GRB 241029A: Swift ToO observations
  37. Fermi trigger No 751861204: Global MASTER-Net observations report
  38. GRB 240821A: Keck/LRIS spectroscopic observations
  39. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  40. GRB 241026A: LBT redshift confirmation
  41. GRB 241025A: further SAO RAS optical observations
  42. GRB 241026A: BTA and Zeiss-1000 optical observations
  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: J-band observations with WINTER
  47. GRB 241025A: SAO RAS optical observations
  48. GRB 241025A: Mondy optical observations
  49. EP241021a: SOAR observations of the optical counterpart
  50. EP241021a: further SAO RAS optical observations
  51. EP 241026b: LBT optical observations
  52. EP241021a: e-MERLIN radio observation
  53. EP EP241026b: Global MASTER-Net observations report
  54. GRB 241026A: KAIT optical observations
  55. EP241026b: EP detection of a fast X-ray transient
  56. Fermi trigger No 751616906: Global MASTER-Net observations report
  57. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  58. GRB 241026A: SAO RAS observations of possible optical afterglow
  59. Fermi GRB 241026A: Global MASTER-Net observations report
  60. Swift GRB241026.95: Global MASTER-Net observations report
  61. GRB241025A: 1.3m DFOT optical afterglow detection
  62. EP241021a: optical follow-up observations with Xinglong Observatory
  63. ​GRB 241025A: optical photometry from Konkoly
  64. GRB 241025A: GROWTH-India Telescope optical observations
  65. GRB 241025A: COLIBRÍ Detection of the Afterglow
  66. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  67. Fermi trigger No 751563375: Global MASTER-Net observations report
  68. Fermi trigger No 751554401: Global MASTER-Net observations report
  69. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  70. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  71. EP 241021a: Swift-XRT observations
  72. EP241021a: optical follow-up observations with the Liverpool Telescope
  73. Fermi GRB 241025A: Global MASTER-Net observations report
  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. EP241021a: Liverpool Telescope optical follow-up observations
  79. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  80. GRB 241025A: TRT optical afterglow observation
  81. Fermi GRB 241024B: Global MASTER-Net observations report
  82. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  83. GRB 241001A: ATCA radio observations
  84. Fermi trigger No 751449953: Global MASTER-Net observations report
  85. EP241021a: SAO RAS optical observations
  86. EP241021a: KAIT optical observations
  87. EP241021a: Optical counterpart observations with the Liverpool Telescope
  88. EP241021a: 1.3m DFOT Optical observations
  89. EP241021a: GSP detects optical candidate counterpart
  90. EP241021a: Optical upper limits with Kinder observations
  91. EP241021a: TRT optical observations
  92. GRB 241018A: SVOM/C-GFT optical observations
  93. EP241021a: NOT likely optical counterpart
  94. EP EP241021a: Global MASTER-Net observations report
  95. GRB241017A: 1.3m DFOT optical upper limit
  96. GRB 241018A: 1.3m DFOT Optical upper limit
  97. EP241021a: GOTO optical upper limits
  98. EP241021a: EP detection of a fast X-ray transient
  99. GRB 241017A/sb24101702: Mephisto optical upper limit
  100. GRB 241018A: SVOM/VT further analysis and counterpart confirmed

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov