Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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').
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"

21455 results found.

  1. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  2. GRB 250704B: Swift/UVOT Upper Limits
  3. GRB 250704A: Swift/UVOT Detection
  4. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  5. GRB 250702F: Kilonova-Catcher optical afterglow detection
  6. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  7. GRB 250704A: SVOM/VT optical observation
  8. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  9. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  10. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  11. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  12. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  13. EP250704a / GRB250704B: Swift-XRT counterpart detection
  14. GRB 250704A: Swift-XRT afterglow detection
  15. GRB 250702B / EP2050702a: FTW optical and NIR observations
  16. Konus-Wind detection of GRB 250702F
  17. GRB 250702F: GROWTH-India Telescope optical observations
  18. EP250702a: WFST optical observations
  19. GRB 250702F: SVOM/VT optical observation
  20. GRB 250702F: Swift/UVOT Detection
  21. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  22. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  23. GRB 250702F: Swift-XRT refined Analysis
  24. GRB 250702F: Fermi GBM Observation
  25. GRB 250702F: Leavitt Observatory optical observations
  26. GRB 250702F: AKO Optical Afterglow Detection
  27. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  28. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  29. GRB 250702F: Skynet Optical Observations
  30. GRB 250424A: VIRT Optical Upper Limit
  31. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  32. GRB 250702F: TRT Optical Observation
  33. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  34. GRB 250702F: REM optical afterglow detection
  35. GRB 250702F: DDOTI Optical Observation
  36. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  37. GRB 250702F: COLIBRÍ Observations of the Afterglow
  38. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  39. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  40. GRB 250702F: Enhanced Swift-XRT position
  41. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  42. GRB 250702F: NOT observations of the optical afterglow
  43. GRB 250702F: MASTER optical afterglow observation
  44. GRB 250702F: GOTO optical counterpart detection
  45. GRB 250702F: Ondrejov D50 optical afterglow detection
  46. GRB 250702F: Swift detection of a burst with an optical counterpart
  47. Swift GRB 250702F: Global MASTER-Net observations report
  48. GRB 250628B: Swift-XRT observations
  49. GRB 250628B: SVOM/VT optical upper limit
  50. GRB 250628A: REM optical/NIR upper limits
  51. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  52. GRB 250628A: VLT/X-shooter upper limits
  53. GRB 250628A: Swift/UVOT Upper Limits
  54. GRB 250628A: Swift-XRT refined Analysis
  55. Swift GRB 250628A: Global MASTER-Net observations report
  56. GRB 250628A: Enhanced Swift-XRT position
  57. GRB 250628A: Swift detection of a burst
  58. GRB 250625A: Swift-BAT refined analysis
  59. GRB 250625A: Leavitt Observatory afterglow detection
  60. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  61. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  62. GRB 250625A: SVOM/C-GFT upper limit in early phase
  63. GRB 250625A: GECAM-B detection
  64. GRB 250625A: Swift/UVOT Upper Limits
  65. GRB 250625A: ABObservatory afterglow detection
  66. GRB 250625A: COLIBRÍ optical observations
  67. GRB 250625A: Fermi-LAT detection
  68. GRB 250625A: Swift-XRT refined Analysis
  69. GRB 250625A: JinShan optical observations
  70. GRB250625A: Fermi GBM Observation
  71. Swift GRB 250625A: Global MASTER-Net observations report
  72. GRB 250625A: SVOM/VT optical confirmation
  73. GRB 250620B: Fermi GBM Observation
  74. GRB 250625A: SAO RAS possible optical afterglow
  75. GRB 250625A: Enhanced Swift-XRT position
  76. GRB 250625A: Swift detection of a burst
  77. GRB 250620A: AstroSat CZTI detection
  78. GRB 241018A: Maidanak optical observations
  79. GRB 250617B: Swift-BAT refined analysis
  80. IPN triangulation of GRB 250620C (long/bright)
  81. GRB 250620A: SVOM/GRM observation of a short burst
  82. GRB250620A: Fermi GBM Observation
  83. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  84. GRB 250619B: Fermi GBM Observation
  85. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  86. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  87. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 250615A: Kilonova-Catcher optical upper limits
  89. GRB 250617B: Assy AZT-20 Optical Observations
  90. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  91. GRB 250615A/EP250615a: FTW optical and NIR observations
  92. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  93. GRB 250617B: Swift/UVOT Detection
  94. GRB 250617B: Kilonova-Catcher optical afterglow detection
  95. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  96. GRB 250617B: NOT NIR observations of the afterglow
  97. GRB 250617B: Swift-XRT refined Analysis
  98. GRB 250617B: SVOM/VT optical observation
  99. Swift GRB 250617B: Global MASTER-Net observations report
  100. GRB 250617B: GOTO optical upper limit

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