Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

35423 results found.

  1. EP250108a / AT2025kg: VLA radio upper limit
  2. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  3. Konus-Wind detection of GRB 250116A
  4. GRB 250116A: GECAM-B detection of a long burst
  5. GRB 241217A / EP241217B: radio detection with the VLA
  6. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  7. Swift Trigger 1282245 is not a GRB
  8. GRB 250116A: Fermi-LAT detection
  9. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  10. GRB 250114B: Swift-XRT afterglow detection
  11. GRB 250114B: SVOM/VT upper limit
  12. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  13. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  14. Konus-Wind detection of GRB 250113A
  15. IPN triangulation of GRB 250113A
  16. GRB 250114B: Liverpool Telescope optical upper limit
  17. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  18. GRB 250114B: Swift-XRT observations
  19. GRB 250114A: LCO optical counterpart detection.
  20. GRB 250114B: OHP/T193 optical upper limit
  21. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  22. GRB 250114A: Swift-XRT refined Analysis
  23. GRB 250114A: LCOGT optical afterglow i-band detection
  24. GRB 250114B : GIT optical upper limit
  25. GRB 250114B: Swift ToO observations
  26. EP250111a: SAO RAS optical upper limit
  27. GRB 250114B: a short GRB detected with INTEGRAL
  28. GRB 250114A: Enhanced Swift-XRT position
  29. GRB 250113A: INTEGRAL/SPI-ACS detection
  30. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  31. GRB 250114A: REM detection of the optical and NIR counterpart
  32. GRB 250114A: LCO optical observations
  33. GRB 250114A: TRT optical observations
  34. Swift GRB 250114A: Global MASTER-Net observations report
  35. GRB 250114A: Swift detection of a burst with an optical counterpart
  36. GRB 250101A: Terskol Zeiss-2000 optical observations
  37. EP250108a / AT 2025kg: SAO RAS optical observations
  38. GRB 250113A: SVOM/GRM observation of a long burst
  39. GRB 250107A: VZLUSAT-2 detection
  40. GRB 250109A / EP250109a: GRBAlpha detection
  41. GRB 250107D: GRBAlpha detection
  42. GRB 250106A: Swift-XRT afterglow detection
  43. EP250111a: KAIT optical observations
  44. GRB 250109A / EP250109a: Mephisto optical upper limits
  45. EP250111a: Mondy optical observation
  46. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  47. GRB 250101B: Fermi GBM Observation
  48. EP250108a: further NOT optical observations
  49. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  50. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  52. GRB 250108A: Swift/XRT afterglow fading
  53. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  54. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  55. Konus-Wind detection of GRB 250107C
  56. GRB 250101A: CMO RC-500 optical observations
  57. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  58. GRB 250109A: Fermi GBM Observation
  59. EP250108a: NOT optical observations
  60. GRB 250109a: GMG Optical Upper Limit
  61. Konus-Wind detection of GRB 250107D (short/hard)
  62. IPN triangulation of GRB 250107D (short/hard)
  63. IPN triangulation of GRB 250107C
  64. GRB 250108B: Gemini-North likely redshift z = 2.197
  65. GRB 250108B: Swift-BAT refined analysis
  66. GRB 250108B: 1.3m DFOT upper limit
  67. GRB 250108B: REM optical/NIR upper limits
  68. GRB 250109A /EP250109a: Fermi GBM Final Localization
  69. GRB 250107C: SVOM/GRM observation
  70. GRB 250101A: Terskol K-800 optical observations
  71. EP250109a: Swift/XRT non-detection
  72. GRB 250108A: Swift/UVOT Upper Limits
  73. GRB 250108A: NOT optical upper limit
  74. GRB 250108B: Swift-XRT refined Analysis
  75. Swift GRB 250108B: Global MASTER-Net observations report
  76. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  77. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  78. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  79. GRB 250103A: 1.6m Mephisto optical observations
  80. GRB 250108A: Swift-XRT afterglow detection
  81. GRB 250108A:SVOM/VT optical candidate
  82. GRB 250108B: Swift/UVOT Upper Limits
  83. GRB 250103A: Swift-XRT afterglow detection
  84. GRB 250108B: Enhanced Swift-XRT position
  85. GRB 250108B: Swift detection of a burst
  86. GRB 250108A: Swift ToO observations
  87. GRB 250108A: SVOM detection of a soft long burst
  88. GRB 250107A: Fermi GBM Observation
  89. GRB 241228B: Fermi-LAT detection
  90. Fermi GRB 250107B: Global MASTER-Net observations report
  91. GRB 250107A: Swift ToO observations
  92. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  93. GRB 250107B: Fermi GBM Final Real-time Localization
  94. GRB 250106A: SVOM/VT 2nd optical deep observation
  95. GRB 250101A: J band upper limit by SYSU 80cm telescope
  96. GRB 250107A: Fermi GBM Final Real-time Localization
  97. GRB 250106A: NOT optical observations
  98. GRB 250103B: REM optical/NIR upper limits
  99. GRB 250101A: REM optical/NIR counterpart detection
  100. GRB 250106A: Swift-XRT observations

Advanced

Download all Circulars as a .tar.gz archive:
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