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"

16159 results found.

  1. GRB 241030A: SVOM/VT optical afterglow observations
  2. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  3. GRB 241030A : MITSuME Akeno optical afterglow detection
  4. GRB 241029A: GROWTH-India Telescope optical follow up
  5. GRB 241030A: TRT optical observations
  6. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  7. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  8. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  9. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  10. GRB 241029A: SAO RAS optical observations
  11. GRB 241026A: SAO RAS optical observations
  12. EP241021a: ATCA radio observations
  13. GRB 241026A: Swift/UVOT Upper Limits
  14. GRB 241029A: Swift-XRT observations
  15. GRB 241029A: AKO Optical Afterglow Detection
  16. GRB 241029A: GOTO optical afterglow detection
  17. EP241021a: continued SOAR observations confirm optical rebrightening
  18. GRB 241029A: MASTER early optical counterpart detection
  19. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  20. GRB 241029A: Mephisto observations
  21. EP 241026b: LBT possible optical counterpart (brightening source)
  22. GRB 241029A: TRT optical afterglow candidate detection
  23. GRB 241029A: SVOM/GRM observation
  24. GRB 240821A: Keck/LRIS spectroscopic observations
  25. EP241021a: Gemini-South detection of optical rebrightening
  26. GRB 241026A: TNOT optical counterpart detection
  27. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  28. GRB 241026A: LBT redshift confirmation
  29. GRB 241025A: further SAO RAS optical observations
  30. GRB 241026A: BTA and Zeiss-1000 optical observations
  31. GRB 241026A: SVOM/GRM observation
  32. EP241026B: GROWTH-India Telescope optical upper limit
  33. GRB 241026A: GROWTH-India Telescope optical observations
  34. GRB 241026A: J-band observations with WINTER
  35. GRB 241025A: SAO RAS optical observations
  36. GRB 241026A: Las Cumbres optical detection
  37. GRB 241025A: Mondy optical observations
  38. EP241021a: SOAR observations of the optical counterpart
  39. EP241021a: further SAO RAS optical observations
  40. EP 241026b: LBT optical observations
  41. EP241021a: e-MERLIN radio observation
  42. GRB 241026A: KAIT optical observations
  43. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  44. GRB 241026A: SAO RAS observations of possible optical afterglow
  45. GRB241025A: 1.3m DFOT optical afterglow detection
  46. EP241021a: optical follow-up observations with Xinglong Observatory
  47. ​GRB 241025A: optical photometry from Konkoly
  48. GRB 241025A: GROWTH-India Telescope optical observations
  49. GRB 241025A: COLIBRÍ Detection of the Afterglow
  50. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  51. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  52. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  53. EP241021a: optical follow-up observations with the Liverpool Telescope
  54. GRB 241025A : SVOM/VT optical afterglow observations
  55. EP241021a: Liverpool Telescope optical follow-up observations
  56. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  57. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  58. GRB 241025A: TRT optical afterglow observation
  59. GRB 241025A: Swift detection of a burst with an optical counterpart
  60. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  61. GRB 241001A: ATCA radio observations
  62. GRB 241010A: VIRT Optical Upper Limit
  63. EP241021a: VLT/FORS2 redshift z = 0.75
  64. EP241021a: SAO RAS optical observations
  65. EP241021a: KAIT optical observations
  66. EP241021a: EP-FXT follow-up observation update
  67. EP241021a: Optical counterpart observations with the Liverpool Telescope
  68. EP241021a: 1.3m DFOT Optical observations
  69. EP241021a: GSP detects optical candidate counterpart
  70. EP241021a: Optical upper limits with Kinder observations
  71. EP241021a: TRT optical observations
  72. GRB 241018A: SVOM/C-GFT optical observations
  73. EP241021a: NOT likely optical counterpart
  74. GRB241017A: 1.3m DFOT optical upper limit
  75. GRB 241018A: 1.3m DFOT Optical upper limit
  76. GRB 241018A: EP-FXT afterglow detection
  77. EP241021a: GOTO optical upper limits
  78. GRB 241018A/sb24101802: Mephisto optical upper limit
  79. GRB 241017A/sb24101702: Mephisto optical upper limit
  80. GRB 241018A: BOOTES-4/MET optical upper limit
  81. GRB 241018A: Mondy optical upper limit
  82. GRB 241018A: GROWTH-India telescope optical upper limit
  83. GRB241018A: XingLong Optical Upper Limit
  84. GRB 241018A: Swift-XRT observations
  85. GRB 241018A: REM optical/NIR upper limits
  86. GRB 241018A: NOT optical observations
  87. GRB 241017A: SVOM/VT follow-up and optical upper limit
  88. GRB 241018A: SVOM/VT follow-up and optical candidate
  89. GRB 241018A: LCO/0.4m optical upper limits
  90. GRB 241006A: VIRT Optical Upper Limit
  91. GRB 240727A: VIRT Optical Upper Limit
  92. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  93. GRB 241017A: GROWTH-India Telescope optical upper limit
  94. GRB 240916A: radio detection with the VLA
  95. GRB 241009A: LCO optical upper limits
  96. GRB 241009A: GRANDMA optical upper limits
  97. GRB 241010A: JinShan optical observations and potential host galaxy
  98. GRB 241010A: J-band observations with WINTER
  99. GRB 241010A: LCO optical observations
  100. GRB 241010A: Swift detection of a burst with an optical counterpart

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