Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. 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"
  1. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  2. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  3. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  4. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  5. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  6. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  7. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  8. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  9. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  10. GRB 240421B: GRBAlpha detection
  11. IceCube Alert 240424.08: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  13. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  14. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  15. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  16. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  17. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  18. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  19. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  20. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  21. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  22. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  23. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  24. GRB 240419A: Swift-BAT refined analysis
  25. GRB 240418A: Swift-BAT refined analysis
  26. LXT240402A/GRB240402B: Chandra X-ray detection
  27. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  29. GRB 240419A: Possible ATCA radio detection
  30. GRB 240421B: ATCA radio observations
  31. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  32. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  33. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  34. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  35. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  36. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  38. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  39. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  42. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  43. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  45. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  46. Fermi trigger No 735470374: Global MASTER-Net observations report
  47. GRB 240421A: Glowbug gamma-ray detection
  48. GRB 240414A: radio detection with the VLA
  49. Fermi-LAT gamma-ray observations of IceCube-240419A
  50. GRB 240414A: AMI-LA radio observations
  51. GRB 240414A: LBT optical detection
  52. GRB 240419B : MITSuME Akeno optical upper limits
  53. GRB 240415B: Swift-XRT observations
  54. GRB 240415A: Swift-XRT refined Analysis
  55. Fermi GRB 240422A: Global MASTER-Net observations report
  56. GRB 240421B: AstroSat CZTI detection
  57. GRB 240422A: Fermi GBM Final Real-time Localization
  58. GRB240421B: Zadko Observations
  59. Fermi GRB 240421B: Global MASTER-Net observations report
  60. Swift GRB 240421B: Global MASTER-Net observations report
  61. GRB 240421B: Fermi GBM Observation
  62. GRB 240421B: Swift-XRT refined Analysis
  63. GRB240421B: BOOTES-5/JGT optical upper limit
  64. GRB 240421B: J-band upper limits from WINTER
  65. GRB 240421B: Swift/UVOT Upper Limits
  66. GRB 240421B: Enhanced Swift-XRT position
  67. Fermi GRB 240421A: Global MASTER-Net observations report
  68. EP240417a: no counterpart detection by SOAR
  69. EP240420a: TNT upper limit to its optical counterpart
  70. EP240420a: Xinglong decaying optical counterpart
  71. GRB 240421B: Swift detection of a burst
  72. EP240420a: Nanshan optical counterpart observations
  73. EP240420a: GWAC-F50A optical upper limit
  74. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  75. GRB 240421A: Fermi GBM Final Real-time Localization
  76. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  77. EP240420a: NOT optical counterpart candidate and potential host
  78. Fermi trigger No 735280430: Global MASTER-Net observations report
  79. GRB240419A: Skynet Optical Afterglow Analysis
  80. GRB240418A - Candidate afterglow from NIRES
  81. IceCube Alert 240419.98: Global MASTER-Net observations report
  82. GRB 240419B: Swift/UVOT Upper Limits
  83. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  84. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  85. EP240420a: EP-WXT detection of a fast X-ray transient
  86. GRB 240419A: Swift/UVOT Upper Limits
  87. GRB 240419B: Swift-XRT refined Analysis
  88. GRB 240419B: optical afterglow from the NOT
  89. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  90. EP240414a: Near-IR observations with NIRES and WINTER
  91. Swift GRB 240419B: Global MASTER-Net observations report
  92. EP240414A: Terskol Zeiss-2000 optical upper limit
  93. GRB 240419B: Enhanced Swift-XRT position
  94. Swift GRB 240419A: Global MASTER-Net observations report
  95. GRB 240418A: Swift/UVOT Upper Limits
  96. GRB 240419A: REM NIR afterglow detection
  97. GRB 240419A: Swift-XRT refined Analysis
  98. GRB 240418A: Swift-XRT refined Analysis
  99. GRB 240419B: Swift detection of a burst
  100. GRB 240411B: 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