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"

28289 results found.

  1. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  2. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  3. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  4. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  5. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  6. EP250704a/GRB250704B : HCT optical and NIR upper limits
  7. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  8. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  9. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  10. GRB 250702F: radio detection with the VLA
  11. IceCube-250706A: EP-FXT follow-up observations
  12. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  13. GRB 250706B/C: Fermi-LAT detection
  14. IceCube-250706A: Global MASTER-Net observations report
  15. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  17. GRB 250706B: Swift/UVOT Detection
  18. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 250702F: GRANDMA observations
  20. GRB 250706A: Swift-XRT refined Analysis
  21. GRB 250706B: refined SVOM/MXT data analysis
  22. GRB 250706A: Swift/UVOT Upper Limits
  23. GRB 250706B: REM optical observations
  24. GRB 250706A: REM optical/NIR observations
  25. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  26. IceCube-250416A: DDOTI Optical Upper Limit
  27. IceCube-250706A: COLIBRÍ optical upper limits
  28. GRB 250706A: JinShan optical upper limits
  29. GRB 250706A: SAO RAS optical observations
  30. EP250704A: NOWT Detection
  31. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  32. GRB250706B: Swift-XRT counterpart detection
  33. GRB 250706B: iTelescope optical observations
  34. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  35. GRB 250706B: SVOM/VT optical observation
  36. GRB 250706B: TRT bright optical counterpart detection
  37. GRB 250706A: GROWTH-India Telescope optical upper limit
  38. GRB 250706B: SVOM detection of a long burst
  39. GRB 250706A: Swift detection of a burst
  40. GRB 250704B: Swift-XRT refined Analysis
  41. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  42. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  43. GRB 250703A: EIRSAT-1 GMOD Detection
  44. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  45. GRB 250704B: Swift/UVOT Upper Limits
  46. GRB 250704A: Swift/UVOT Detection
  47. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  48. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  49. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  50. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  51. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  52. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  53. GRB 250702F: Kilonova-Catcher optical afterglow detection
  54. GRB 250702F: Monte Agliale Observatory optical observations
  55. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  56. EP250704a / GRB 250704B: JinShan optical observations
  57. EP250704a / GRB 250704B: SAO RAS optical observations
  58. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  59. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  60. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  61. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  62. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  63. EP250704a / GRB250704B: Swift-XRT counterpart detection
  64. GRB 250704A: Swift-XRT afterglow detection
  65. EP250704a / GRB 250704B - REM observations
  66. GRB 250702F: GROWTH-India Telescope optical observations
  67. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  68. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  69. EP250702a: WFST optical observations
  70. EP250704a: COLIBRÍ optical counterpart candidate
  71. EP250704a: Einstein Probe detection of an X-ray transient
  72. GRB 250704A: REM detection of the optical afterglow
  73. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  74. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  75. GRB 250704A: SVOM detection of a burst
  76. GRB 250702F: Swift/UVOT Detection
  77. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  78. GRB 250702F: Swift-XRT refined Analysis
  79. GRB 250702F: Fermi GBM Observation
  80. GRB 250702F: Leavitt Observatory optical observations
  81. GRB 250702F: AKO Optical Afterglow Detection
  82. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  83. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  84. GRB 250702F: Skynet Optical Observations
  85. GRB 250424A: VIRT Optical Upper Limit
  86. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  87. GRB 250702F: TRT Optical Observation
  88. GRB 250703A: DDOTI Optical Upper Limit
  89. GRB 250702F: REM optical afterglow detection
  90. EP250702a: Global MASTER-Net observations report
  91. GRB 250702F: DDOTI Optical Observation
  92. GRB 250702F: COLIBRÍ Observations of the Afterglow
  93. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  94. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  95. GRB 250702F: Enhanced Swift-XRT position
  96. GRB 250702F: NOT observations of the optical afterglow
  97. GRB 250702F: Swift detection of a burst with an optical counterpart
  98. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  99. GRB 250702A: Fermi GBM Detection
  100. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate

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