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"

11503 results found.

  1. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  2. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  3. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  4. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  5. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  6. EP250704a / GRB250704B: Swift-XRT counterpart detection
  7. GRB 250704A: Swift-XRT afterglow detection
  8. Konus-Wind detection of GRB 250702F
  9. EP250704a: COLIBRÍ optical counterpart candidate
  10. EP250704a: Einstein Probe detection of an X-ray transient
  11. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  12. GRB 250704A: SVOM detection of a burst
  13. Fermi GRB 250703A: Global MASTER-Net observations report
  14. GRB 250702F: Swift-XRT refined Analysis
  15. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  16. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  17. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  18. EP250702a: Global MASTER-Net observations report
  19. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  20. Fermi GRB 250702C: Global MASTER-Net observations report
  21. Konus-Wind detection of GRB 250627A
  22. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  23. GRB 250628B: Swift-XRT observations
  24. GRB 250628A: REM optical/NIR upper limits
  25. GRB 250628B: SVOM detection of a long burst
  26. GRB 250628A: Swift-XRT refined Analysis
  27. Fermi GRB 250626A: Global MASTER-Net observations report
  28. GRB 250628A: Swift detection of a burst
  29. GRB 250625A: Leavitt Observatory afterglow detection
  30. GRB 250625A: ABObservatory afterglow detection
  31. GRB 250625A: OHP/T193 optical detection
  32. GRB 250625A: Fermi-LAT detection
  33. GRB 250625A: Swift-XRT refined Analysis
  34. Swift GRB 250625A: Global MASTER-Net observations report
  35. GRB 250620B: Fermi GBM Observation
  36. GRB 250625A: SAO RAS possible optical afterglow
  37. Fermi GRB 250625A: Global MASTER-Net observations report
  38. GRB 250625A: Swift detection of a burst
  39. GRB 250620A: AstroSat CZTI detection
  40. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  41. GRB 241018A: Maidanak optical observations
  42. GRB 250620C: AstroSat CZTI detection
  43. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  44. Fermi GRB 250623A: Global MASTER-Net observations report
  45. Fermi trigger No 772190032: Global MASTER-Net observations report
  46. Konus-Wind detection of GRB 250620C
  47. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  48. GRB250620A: Fermi GBM Observation
  49. Fermi GRB 250621A: Global MASTER-Net observations report
  50. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  51. GRB250620C: Fermi GBM Observation
  52. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  53. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  54. GRB 250620C: Fermi GBM Final Real-time Localization
  55. Fermi trigger No 772128434: Global MASTER-Net observations report
  56. GRB 250620B: Fermi GBM Final Real-time Localization
  57. GRB 250620A: Fermi GBM Final Real-time Localization
  58. Fermi trigger No 772058337: Global MASTER-Net observations report
  59. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  60. GRB 250617B: Assy AZT-20 Optical Observations
  61. GRB 250615A/EP250615a: FTW optical and NIR observations
  62. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  63. GRB 250617B: COLIBRÍ optical observations
  64. GRB 250617B: Swift-XRT refined Analysis
  65. GRB 250617B: Swift detection of a burst with an optical counterpart
  66. EP#01709178975: Swift-XRT counterpart detection
  67. Konus-Wind detection of GRB 250615A / EP250615a
  68. GRB 250615A / EP250615a: AstroSat CZTI detection
  69. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  70. Fermi trigger No 771752663: Global MASTER-Net observations report
  71. sb25061218: Swift-XRT observations
  72. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  73. EP250612a: SVOM/VT optical candidate
  74. sb25061207: Swift-XRT observations
  75. GRB 250610B: Swift-XRT refined Analysis
  76. EP250612a: Einstein Probe detection of an X-ray transient
  77. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  78. sb25061207: SVOM detection of a X-ray transient
  79. Swift GRB250612.04: Global MASTER-Net observations report
  80. GRB 250610B: Swift-XRT counterpart detection
  81. GRB 250610B: SVOM/VT optical counterpart
  82. GRB 250610B: OHP/T120 optical counterpart candidate
  83. GRB 250610B: GOTO optical upper limit
  84. EP250610a: Global MASTER-Net observations report
  85. GRB 250610B: SVOM detection of a long burst
  86. EP250610a: Swift-XRT counterpart detection
  87. EP250610a: Einstein Probe detection of an X-ray transient
  88. Fermi trigger No 771072240: Global MASTER-Net observations report
  89. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  90. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  91. GRB 250605A: Swift-XRT refined Analysis
  92. Fermi GRB 250606A: Global MASTER-Net observations report
  93. Fermi trigger No 770867684: Global MASTER-Net observations report
  94. GRB 250605A: LT optical observations
  95. Konus-Wind detection of GRB 250601A
  96. Fermi Gamma-ray Burst Monitor trigger 770675211/250603852 is not a GRB
  97. Swift GRB250603.05: Global MASTER-Net observations report
  98. GRB 250602A: Fermi-LAT detection
  99. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  100. Fermi GRB 250531A: Global MASTER-Net observations report

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