Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28105 results found.

  1. GRB 250114A: Enhanced Swift-XRT position
  2. GRB 250113A: INTEGRAL/SPI-ACS detection
  3. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  4. GRB 250114A: REM detection of the optical and NIR counterpart
  5. Swift GRB250114A: Global MASTER-Net OT detection
  6. GRB 250114A: LCO optical observations
  7. GRB 250114A: TRT optical observations
  8. GRB 250114A: Swift detection of a burst with an optical counterpart
  9. GRB 250101A: Terskol Zeiss-2000 optical observations
  10. GRB 250107A: VZLUSAT-2 detection
  11. GRB 250109A / EP250109a: GRBAlpha detection
  12. GRB 250107D: GRBAlpha detection
  13. GRB 250106A: Swift-XRT afterglow detection
  14. EP250111a: KAIT optical observations
  15. GRB 250109A / EP250109a: Mephisto optical upper limits
  16. EP250108a: Mephisto detection
  17. EP250111a: Swift/XRT detection and fading
  18. EP250108a / AT 2025kg: Swift UVOT detections
  19. EP250111a: a new X-ray transient detected by Einstein Probe
  20. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  21. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  22. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  23. GRB 250108A: Swift/XRT afterglow fading
  24. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  25. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  26. Konus-Wind detection of GRB 250107C
  27. GRB 250101A: CMO RC-500 optical observations
  28. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  29. EP250108a: NOT optical observations
  30. EP250109a: Swift/UVOT non-detection
  31. Konus-Wind detection of GRB 250107D (short/hard)
  32. EP250108a: Liverpool Telescope likely optical counterpart
  33. GRB 250108B: Gemini-North likely redshift z = 2.197
  34. GRB 250108B: 1.3m DFOT upper limit
  35. GRB 250108B: REM optical/NIR upper limits
  36. GRB 250109A /EP250109a: Fermi GBM Final Localization
  37. GRB 250101A: Terskol K-800 optical observations
  38. EP250109a: GOTO optical upper limits
  39. EP250109a: Swift/XRT non-detection
  40. GRB 250108A: Swift/UVOT Upper Limits
  41. EP250109a: EP-WXT detection of an X-ray transient
  42. GRB 250108A: NOT optical upper limit
  43. EP250108a: EP-WXT detection of an X-ray transient
  44. GRB 250108B: Swift-XRT refined Analysis
  45. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  46. GRB 250103A: 1.6m Mephisto optical observations
  47. GRB 250108A: Swift-XRT afterglow detection
  48. GRB 250108A:SVOM/VT optical candidate
  49. GRB 250108B: Swift/UVOT Upper Limits
  50. GRB 250103A: Swift-XRT afterglow detection
  51. GRB 250108B: Enhanced Swift-XRT position
  52. GRB 250108B: Swift detection of a burst
  53. GRB 250108A: Swift ToO observations
  54. GRB 250108A: SVOM detection of a soft long burst
  55. GRB 241228B: Fermi-LAT detection
  56. GRB 250107A: Swift ToO observations
  57. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  58. GRB 250107B: Fermi GBM Final Real-time Localization
  59. GRB 250106A: SVOM/VT 2nd optical deep observation
  60. GRB 250101A: J band upper limit by SYSU 80cm telescope
  61. GRB 250107A: Fermi GBM Final Real-time Localization
  62. EPWXT01709129925: Xinglong optical observations
  63. GRB 250106A: NOT optical observations
  64. GRB 250103B: REM optical/NIR upper limits
  65. GRB 250101A: REM optical/NIR counterpart detection
  66. GRB 250106A: Swift-XRT observations
  67. GRB 250106A: SVOM/VT optical candidate
  68. GRB 250106A: Swift ToO observations
  69. GRB 250106A: SVOM detection of a long burst
  70. GRB 241229A: SVOM/VT optical upperlimit
  71. GRB 250103B: Swift-XRT refined Analysis
  72. GRB 250103B: LCO/1m optical afterglow candidate detection
  73. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  74. GRB 250103A: Swift-XRT observations
  75. GRB 250101A: 1.3m DFOT optical afterglow detection
  76. GRB 241229A: 1.3m DFOT upper limit
  77. GRB 241228B: 1.3m DFOT Optical observations
  78. GRB 241228A: 1.3m DFOT upper limit
  79. GRB 250103A: NOT spectroscopic redshift
  80. GRB 250103B：SVOM/VT optical counterpart
  81. GRB 250103A: Montarrenti Observatory optical detection
  82. GRB 250101A: further LCOGT optical afterglow observations
  83. GRB 250103A: NOT optical observations
  84. GRB 250103A: TSHAO optical upper limit
  85. GRB 250103B: LCOGT Optical Upper Limit
  86. GRB 250103A: Swift ToO observations
  87. GRB 250101a: Liverpool Telescope optical follow-up
  88. GRB 250103B: SVOM detection of a long burst
  89. GRB 250103B: Swift detection of a burst
  90. GRB 250103A: GOTO optical upper limit
  91. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  92. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  93. GRB 250103A: SVOM detection of a long burst
  94. EP250101a: Xinglong optical upper limit
  95. GRB 250102A: Fermi GBM Final Real-time Localization
  96. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  97. GRB 250101A: LCO optical counterpart detection
  98. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  99. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  100. GRB 250101A: Swift/UVOT Detection

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