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"

28224 results found.

  1. GRB 240426A: VZLUSAT-2 detection
  2. GRB 240425A: VZLUSAT-2 detection
  3. GRB240430A: Fermi GBM Final Localization
  4. GRB 240501B: AstroSat CZTI detection
  5. GRB 240501A: Fermi GBM Final Real-time Localization
  6. GRB 240408B: VZLUSAT-2 detection
  7. GRB 240407A: VZLUSAT-2 detection
  8. X-ray transient EP240414a: Detection of associated supernova
  9. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  10. GRB 240425A: GRBAlpha detection
  11. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  12. GRB 240429A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  14. LIGO/Virgo/KAGRA S240429an: Retraction of GW compact binary merger candidate
  15. GRB 240428A: Fermi GBM Final Real-time Localization
  16. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  17. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  18. EP240426b: AST3-2 optical upper limit
  19. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  20. EP240426b: EP-WXT detection of a new fast X-ray transient
  21. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  22. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  23. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  24. GRB 240426A: AstroSat CZTI detection
  25. EP240426a: YAHPT optical upper limit
  26. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  27. GRB 240414A: NOEMA detection
  28. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  29. EP240426a: GMG optical upper limit
  30. LVK S240422ed: Further Swift-XRT followup of three sources
  31. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  32. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  33. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  34. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  35. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  36. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  37. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  38. GRB 240425A: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  40. GRB 240422A: Glowbug gamma-ray detection
  41. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  42. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  43. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  44. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  45. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  46. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  47. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  48. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  49. GRB 240421B: GRBAlpha detection
  50. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  51. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  52. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  53. LXT240402A/GRB240402B: Chandra X-ray detection
  54. GRB 240419A: Possible ATCA radio detection
  55. GRB 240421B: ATCA radio observations
  56. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  57. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  58. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  59. GRB 240421A: Glowbug gamma-ray detection
  60. GRB 240414A: radio detection with the VLA
  61. GRB 240414A: AMI-LA radio observations
  62. GRB 240414A: LBT optical detection
  63. GRB 240419B : MITSuME Akeno optical upper limits
  64. GRB 240415B: Swift-XRT observations
  65. GRB 240415A: Swift-XRT refined Analysis
  66. GRB 240421B: AstroSat CZTI detection
  67. GRB 240422A: Fermi GBM Final Real-time Localization
  68. GRB 240421B: Swift-XRT refined Analysis
  69. GRB240421B: BOOTES-5/JGT optical upper limit
  70. GRB 240421B: Swift/UVOT Upper Limits
  71. GRB 240421B: Enhanced Swift-XRT position
  72. EP240417a: no counterpart detection by SOAR
  73. EP240420a: TNT upper limit to its optical counterpart
  74. GRB 240421B: Swift detection of a burst
  75. GRB 240421A: Fermi GBM Final Real-time Localization
  76. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  77. GRB240419A: Skynet Optical Afterglow Analysis
  78. GRB240418A - Candidate afterglow from NIRES
  79. GRB 240419B: Swift/UVOT Upper Limits
  80. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  81. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  82. EP240420a: EP-WXT detection of a fast X-ray transient
  83. GRB 240419A: Swift/UVOT Upper Limits
  84. GRB 240419B: Swift-XRT refined Analysis
  85. GRB 240419B: optical afterglow from the NOT
  86. GRB 240419B: Enhanced Swift-XRT position
  87. GRB 240418A: Swift/UVOT Upper Limits
  88. GRB 240419A: REM NIR afterglow detection
  89. GRB 240419A: Swift-XRT refined Analysis
  90. GRB 240418A: Swift-XRT refined Analysis
  91. GRB 240419B: Swift detection of a burst
  92. GRB 240411B: Swift/UVOT Detection
  93. EP240417a: YAHPT Optical Upper Limits
  94. GRB240418A: YAHPT Upper Limits
  95. GRB 240419A: VLT/UVES redshift of z = 5.178
  96. GRB 240419A: VLT optical afterglow detection
  97. GRB 240419A: Enhanced Swift-XRT position
  98. GRB 240419A: Prompt enhanced Swift-XRT position
  99. GRB 240419A: Swift detection of a burst
  100. GRB 240418A: TSHAO Zeiss-1000 optical upper limit

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov