Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. 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').

17085 results found.

  1. GRB 240415A 1.3m DFOT Optical upper limit
  2. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  3. LVK S240422ed: Further Swift-XRT followup of three sources
  4. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  5. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  6. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  7. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  8. GRB 240419B: Swift-BAT refined analysis
  9. GRB 240421B: Swift-BAT refined analysis
  10. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  11. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  12. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  13. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  14. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  15. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  16. GRB 240421B: GRBAlpha detection
  17. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  18. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  19. GRB 240419A: Swift-BAT refined analysis
  20. GRB 240418A: Swift-BAT refined analysis
  21. LXT240402A/GRB240402B: Chandra X-ray detection
  22. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  23. GRB 240419B : MITSuME Akeno optical upper limits
  24. GRB 240415B: Swift-XRT observations
  25. GRB 240415A: Swift-XRT refined Analysis
  26. GRB 240421B: AstroSat CZTI detection
  27. GRB240421B: Zadko Observations
  28. Swift GRB 240421B: Global MASTER-Net observations report
  29. GRB 240421B: Fermi GBM Observation
  30. GRB 240421B: Swift-XRT refined Analysis
  31. GRB240421B: BOOTES-5/JGT optical upper limit
  32. GRB 240421B: Swift/UVOT Upper Limits
  33. GRB 240421B: Enhanced Swift-XRT position
  34. GRB 240421B: Swift detection of a burst
  35. GRB240419A: Skynet Optical Afterglow Analysis
  36. GRB 240419B: Swift/UVOT Upper Limits
  37. GRB 240419A: Swift/UVOT Upper Limits
  38. GRB 240419B: Swift-XRT refined Analysis
  39. Swift GRB 240419B: Global MASTER-Net observations report
  40. GRB 240419B: Enhanced Swift-XRT position
  41. Swift GRB 240419A: Global MASTER-Net observations report
  42. GRB 240418A: Swift/UVOT Upper Limits
  43. GRB 240419A: Swift-XRT refined Analysis
  44. GRB 240418A: Swift-XRT refined Analysis
  45. GRB 240419B: Swift detection of a burst
  46. GRB 240411B: Swift/UVOT Detection
  47. GRB240418A: YAHPT Upper Limits
  48. GRB 240419A: Enhanced Swift-XRT position
  49. GRB 240419A: Prompt enhanced Swift-XRT position
  50. GRB 240419A: Swift detection of a burst
  51. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  52. GRB 240418A: Enhanced Swift-XRT position
  53. Swift GRB240418.85: Global MASTER-Net observations report
  54. GRB 240418A: Swift detection of a burst
  55. Improved IPN triangulation of GRB 240411A
  56. GRB 240415A: Glowbug gamma-ray detection
  57. GRB 240414A: Glowbug gamma-ray detection
  58. GRB 240415B: GECAM-B detection
  59. GRB 240415A: Swift-BAT refined analysis
  60. GRB 240411A: Glowbug gamma-ray detection
  61. GRB 240414A: Swift-BAT refined analysis
  62. GRB 240414A: AbAO optical upprer limit
  63. GRB 240415A: Swift/UVOT Detection
  64. GRB 240415A: Fermi GBM Observation
  65. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  66. GRB 240415A: Enhanced Swift-XRT position
  67. GRB 240415B: Swift ToO observations
  68. GRB 240415B: Swift/BAT-GUANO Correction
  69. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  70. GRB 240414A: Fermi GBM Observation
  71. GRB 240414A: Swift/UVOT Detection
  72. LXT 240402A/GRB 240402B: Swift follow-up observations
  73. GRB 240414A: Mondy optical observations
  74. GRB 240415A: Prompt Swift-XRT observations
  75. GRB 240415A: Swift detection of a burst
  76. GRB 240414A: Swift-XRT refined Analysis
  77. GRB 240414A: Enhanced Swift-XRT position
  78. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  79. GRB 240414A: Skynet Optical Afterglow Observations
  80. Swift GRB 240414A: Global MASTER-Net observations report
  81. IPN triangulation of GRB 240410A
  82. IPN triangulation of GRB 240411A
  83. GRB 240414A : MITSuME Akeno optical upper limits
  84. GRB 240414A: Swift detection of a burst
  85. GRB 240411B: Swift-BAT refined analysis
  86. GRB 240411B: Swift-XRT refined Analysis
  87. GRB 240411B: 1.3m DFOT Optical observations
  88. GRB 240411B: Enhanced Swift-XRT position
  89. GRB 240411B: Swift detection of a burst
  90. EP240408A: MASTER optical observations
  91. EP240408a: GROND detection of a candidate counterpart
  92. EP240408a: Swift follow-up observation
  93. Swift Trigger 1220736: detection of 4U 1543-62.
  94. Swift satellite resumes pointed science observations
  95. GRB 240318A: Fermi GBM Observation
  96. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  97. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  98. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  99. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  100. GRB 240317B: Swift/BAT-GUANO Angular Error Correction

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