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"

27917 results found.

  1. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  2. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  3. GRB 250818A: AstroSat CZTI detection
  4. GRB 250818B: Swift/UVOT Detection
  5. GRB 250820A: Fermi GBM Final Real-time Localization
  6. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  7. GRB 250818B: SAO RAS optical observations
  8. Swift GRB 250818A: Global MASTER-Net observations report
  9. GRB 250818A: Swift-XRT refined Analysis
  10. GRB 250818B: EP-FXT counterpart detection
  11. GRB 250818A: Swift-BAT refined analysis
  12. GRB 250818C: Fermi GBM Final Real-time Localization
  13. GRB 250818B: Keck redshift of the optical afterglow
  14. GRB 250818A: Swift/UVOT Upper Limits
  15. GRB 250818A: Enhanced Swift-XRT position
  16. GRB 250818A: Fermi GBM Observation
  17. GRB 250818B: SVOM/VT optical observation
  18. GRB 250814A: Further GRAWITA TNG NIR observations
  19. GRB 250818B: Swift-XRT afterglow detection
  20. GRB 250818B: SVOM detection of a short burst
  21. GRB 250818A: Swift detection of a burst
  22. GRB 250818A: Fermi GBM Final Real-time Localization
  23. sb25081602: Swift-XRT observations
  24. SVOM/sb25081602: detection of a likely X-ray transient
  25. GRB 250816A: Fermi GBM Final Real-time Localization
  26. GRB 250814A: Swift-BAT refined analysis
  27. GRB 250815A: Fermi GBM Final Localization
  28. GRB 250814A: Further COLIBRÍ optical upper limit
  29. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  30. GRB 250814A: GRAWITA TNG NIR observations
  31. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  32. GRB250814A: TRT optical upper limits
  33. GRB 250814C: SVOM/GRM observation of a short burst
  34. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  35. GRB 250813B: SVOM/GRM observation
  36. GRB 250814A: P200/WIRC observations of the afterglow candidate
  37. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  38. GRB 250814A: KAIT optical upper limit
  39. GRB 250814A: Swift-XRT refined Analysis
  40. GRB 240814A: Fermi GBM Observation
  41. GRB 250814A: Possible afterglow candidate from P200/WIRC
  42. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  43. Swift GRB250814.32: Global MASTER-Net observations report
  44. GRB 250814A: J-band upper limit from WINTER
  45. GRB 250813B: SVOM/VT optical observations
  46. GRB 250814A: COLIBRÍ optical upper limit
  47. GRB 250814B: Fermi GBM Final Real-time Localization
  48. GRB 250813A: AstroSat CZTI detection
  49. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  50. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  51. GRB 250814A: DDOTI Optical Upper Limit
  52. GRB 250813B: EP-FXT counterpart detection
  53. GRB 250813B: Swift-XRT afterglow detection
  54. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  55. GRB 250814A: Fermi GBM Final Real-time Localization
  56. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  57. GRB 250813B: Ondrejov D50 optical afterglow detection
  58. GRB 250813B: SVOM detection of a bright long burst
  59. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  60. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  61. EP250812a: NOT, NTT, and GS observations
  62. GRB 250812A: Swift/UVOT Detection
  63. GRB 250813A: Fermi GBM Final Localization
  64. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  65. EP250812a: Liverpool Telescope upper limits
  66. EP250812a: SVOM/VT optical counterpart
  67. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 250812A: EP-FXT counterpart detection
  69. GRB 250812A: Swift ToO observations
  70. GRB 250807B: Swift-BAT refined analysis
  71. EP 250812a: GOTO optical upper limit
  72. GRB 250812A: Kilonova-Catcher optical afterglow detection
  73. EP250812a: Swift-XRT counterpart detection
  74. EP250812a: Einstein Probe detection of an X-ray transient
  75. GRB 250812A: SVOM/VT optical afterglow confirmation
  76. GRB 250812A: Swift-XRT afterglow detection
  77. GRB 250812A: TRT likely optical counterpart detection
  78. GRB 250812A: SVOM detection of a faint long burst
  79. GRB 250809A: Swift-BAT refined analysis
  80. GRB 250807A: Swift-BAT refined analysis
  81. GRB 250809A: Swift/UVOT Detection
  82. Corrected Swift-XRT Refined Analysis of GRB 250809A
  83. GRB 250809A: Swift-XRT refined Analysis
  84. GRB 250807B: SVOM/VT optical observation
  85. GRB 250809A: LCOGT Optical Upper Limits
  86. GRB 250702B: Chandra X-ray Detection
  87. GRB 250808A: VLT X-shooter candidate counterpart
  88. GRB 250809A: Prompt enhanced Swift-XRT position
  89. GRB 250809A: Swift detection of a gamma ray burst
  90. GRB 250808A: Swift-XRT candidate counterpart detection
  91. GRB 250807A: SVOM/VT optical continued observation
  92. GRB 250808A: SVOM detection of a long burst
  93. GRB 250808A: Fermi GBM Final Real-time Localization
  94. Konus-Wind detection of GRB 250807A
  95. GRB 250807B: Swift/UVOT Detection
  96. GRB 250807B: Kilonova-Catcher optical afterglow detection
  97. GRB 250807A: Swift/UVOT Detection
  98. GRB 250807A: Swift-XRT refined Analysis
  99. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  100. GRB 250806A: SVOM/MXT refined analysis

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